Extrusion and Properties of Nanoclay Added Composite Polypropylene Monofilaments 
by 
 Erdem Selver 
 
 
A thesis submitted to the Graduate Faculty of 
Auburn University 
in partial fulfillment of the 
requirements for the Degree of 
Master of Science of Polymer and Fiber Engineering 
 
Auburn, Alabama 
May 14, 2010 
 
Copyright 2010 by Erdem Selver 
 
 
Approved by 
 
Sabit Adanur, Chair, Professor of Polymer and Fiber Engineering 
Peter Schwartz, Professor of Polymer and Fiber Engineering 
Xinyu Zhang, Assistant Professor of Polymer and Fiber Engineering
ii 
 
Abstract 
 
This study focuses on combining traditional polymeric materials with nanoclays to 
engineer new composite monofilaments for nontraditional industries using extrusion process. 
Polypropylene/nanoclay composite monofilaments were produced using single and twin screw 
extruders, and the structure and properties of the new monofilaments were characterized using 
scanning electron microscopy (SEM), X-Ray diffraction (XRD), Fourier transform infrared 
spectrometry (FTIR), thermal gravimetric analyzer (TGA), differential scanning calorimeter 
(DSC), and Instron universal testing machine. Composite monofilaments were prepared at 
different weight percentage (1, 2, and 3%) of nanoclay (Cloisite 15A) and different amount of 
compatabilizer (10, 15, and 20%) contents with single screw extruder. Twin screw extruder was 
used to produce composite monofilaments with different weight percentage (0.5, 1, and 1.5 %) 
and types of nanoclay (Cloisite 15A and 30B). The results showed that the amount of nanoclay 
and compatabilizer affect the formation and final properties of the new monofilaments. It was 
observed that tensile strength of composite monofilament decreased compared to pure 
polypropylene monofilaments. Melting temperature and degree of crystallinity were not affected 
much; however, there was significant increase in decomposition temperature of composite 
polypropylene monofilaments. 
 
 
 
 
iii 
 
Acknowledgments 
 
 
I am deeply grateful to my advisor, Dr. Sabit Adanur for his academic guidance, 
encouragement, and friendship during my study at Auburn University. I also wish to thank my 
committee members, Dr. Peter Schwartz and Dr. Xinyu Zhang for their suggestions. Additional 
thanks to all Polymer and Fiber Engineering faculty members for their guidance during my 
graduate studies. I am also grateful to Mr. David Clark for his assistance to use processing 
machines in the Polymer and Fiber Engineering Department. 
Finally, I would like to thank my parents for their support and encouragement even if 
they are in Turkey.  Special thanks to Ayca Dogrul for her love and patience during my graduate 
studies. 
 
 
 
 
 
 
 
 
 
 
iv 
 
Table of Contents 
 
 
Abstract ........................................................................................................................................... ii 
Acknowledgments.......................................................................................................................... iii 
List of Tables ................................................................................................................................ vii 
List of Figures .............................................................................................................................. viii 
Chapter 1   Introduction and Background ........................................................................................1 
    1.  Nanocomposites Structures .....................................................................................................3 
       1.1. Layered Silicates ................................................................................................................5 
       1.2. Nanoparticle Dispersion ...................................................................................................10 
 1.2.1. In situ Polymerization ..............................................................................................10 
 1.2.2. Solution Blending ....................................................................................................10 
 1.2.3. Melt Intercalation .....................................................................................................10 
 1.2.4. Template Synthesis ..................................................................................................11 
Chapter 2   Manufacturing and Characterization of PP/Clay Monofilament.................................13 
    1. Materials ................................................................................................................................13 
    2. Machines Used For Manufacturing .......................................................................................13 
       2.1. Extrusion Machine ...........................................................................................................15 
 2.1.1. Extruder Parts...........................................................................................................16 
  2.1.1.1. Screw.........................................................................................................16 
v 
 
2.1.1.2. Barrel.........................................................................................................17 
                        2.1.1.3. Die .............................................................................................................17 
  2.1.1.4. Melt Pump .................................................................................................18 
                        2.1.1.5. Breaker Plate .............................................................................................19 
 2.1.2. Processing ................................................................................................................20 
2.1.2.1. Row Material Blending and Mixing .........................................................20 
2.1.2.2. Drying .......................................................................................................21 
2.1.2.3. Feeding Polymer to Extruder ....................................................................21 
2.1.2.4. Shaping and Drawing ................................................................................23 
2.1.2.5. Solidification and Cooling ........................................................................29 
2.1.2.6. Winding.....................................................................................................29 
 2.1.3. Differences between Single and Twin Screw Extruders ..........................................30 
    3. Preparation of PP/Nanoclay Composite Monofilaments .......................................................31 
       3.1. By Using Single Screw Extruder .....................................................................................31 
       3.2. By Using Twin and Single Screw Extruders in Sequence ...............................................32 
    4. Characterization .....................................................................................................................34 
Chapter 3 Results and Discussion ..................................................................................................36 
    1. Single Screw Extrusion Results .............................................................................................36 
       1.1. SEM Microscopy .............................................................................................................36 
       1.2. FTIR .................................................................................................................................38 
       1.3. X-Ray Diffraction ............................................................................................................39 
       1.4. Thermal Behavior ............................................................................................................40 
       1.5. Mechanical Behaviors ......................................................................................................45 
vi 
 
    2. Twin and Single Screw Extruder Results ..............................................................................47 
       2.1. Thermal Behavior of Pellets ............................................................................................47 
       2.2. Mechanical and Thermal Behavior of Composite Monofilaments ..................................51 
       2.3. SEM Results of Composite Monofilaments  ...................................................................55 
Chapter 4 Nanoclay and Polypropylene Market ............................................................................59 
    1. Nanocomposite Market ..........................................................................................................59 
    2. Polypropylene Market ............................................................................................................60 
Chapter 5 Conclusions and Future Recommendations ..................................................................65 
References ......................................................................................................................................67 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
vii 
 
List of Tables 
 
 
Table 1. Chemical structure of phyllosilicates .................................................................................5 
Table 2.  Parameter Settings of monofilament processing ............................................................25 
Table 3.  Parameter settings of monofilament processing with different heater temperature .......26 
Table 4.  Diameter variation of different monofilaments ..............................................................27 
Table 5.  Differences between single and twin screw extruders ....................................................30 
Table 6.  Sample codes and blends of master batches for single screw extruder ..........................31 
Table 7.  Temperature settings of the single screw extruder .........................................................32 
Table 8.  Sample codes and blends of master batches for twin screw extruder .............................33 
Table 9.  Temperature settings of the twin screw extruder ............................................................34 
Table 10.  Diffraction peaks of the samples at 2uni04E8 angle range .....................................................40 
Table 11.  Thermal and tensile results of composite monofilaments ............................................41 
Table 12.  Thermal behavior of pure polypropylene and nanoclay added pellets .........................48 
Table 13.  Thermal and mechanical properties of composite monofilaments ...............................51 
Table 14.  Nanocomposite consumption by value (2005-2011) ....................................................59 
Table 15.  Global consumption of nanocomposites (2005-2011) ..................................................59 
Table 16.  World chemical fiber production in 2007 .....................................................................60 
Table 17.  Global production of synthetic fibers (1,000/tons)  ......................................................61 
Table 18.  Global production of polyolefin fibers .........................................................................62
viii 
 
List of Figures 
 
Figure 1.  Level of nanoclay dispersion ...........................................................................................5 
Figure 2.  Structure of a 2:1 layered silicate ....................................................................................6 
Figure 3.  Cation-exchange process between alkylammonium ions and metallic cations ...............7 
Figure 4.  Dispersion of silicate layers in polymer matrix via PP-MA............................................9 
Figure 5.  Organoclay dispersion and exfoliation during melt processing ....................................11 
Figure 6.  Single screw extrusion machine ....................................................................................14 
Figure 7.  Twin screw extrusion machine ......................................................................................14 
Figure 8.  Longitudinal cross section of an extruder  ....................................................................16 
Figure 9.  Schematic of a typical single screw  ..............................................................................16 
Figure 10.  A typical twin screw .....................................................................................................17 
Figure 11.  Single screw extruder die  ...........................................................................................18 
Figure 12.  Operation of melt pump ..............................................................................................19 
Figure 13.  Breaker plate ................................................................................................................20 
Figure 14.  Flood feeding machine ................................................................................................21 
Figure 15.  Starve feeding ..............................................................................................................22 
Figure 16.  Crammer feeding .........................................................................................................22 
Figure 17.  Melt feeding.................................................................................................................23 
Figure 18.  Extrudate expansion ....................................................................................................23 
Figure 19.  Godets and heater units of the single screw extruder ..................................................24 
ix 
 
Figure 20.  Molecular orientation of  fibers during stretching .......................................................24 
Figure 21.  Diameter changes with different draw-down ratios  ...................................................25 
Figure 22.  Tensile strength of monofilaments at different draw-down ratios ..............................28 
Figure 23.  Tensile strength of monofilaments at different heater temperatures ...........................28 
Figure 24.  Winder section .............................................................................................................29 
Figure 25.  SEM images of surface views .....................................................................................37 
Figure 26.  FTIR spectra of pure and composite monofilaments ..................................................38 
Figure 27.  XRD curves of pure polypropylene and composite monofilaments ...........................39 
Figure 28.  Melting behavior of pure and composite polypropylene monofilaments ....................42 
Figure 29.  Decomposition behavior of pure and composite polypropylene monofilaments at 
different nanoclay loadings ............................................................................................................43 
Figure 30.  Determination of pure polypropylene monofilament?s decomposition temperature ..44 
Figure 31.  Decomposition behavior of pure and composite polypropylene monofilaments at 
different compatabilizer loadings ..................................................................................................45 
Figure 32.  Tensile behavior of pure and composite monofilaments .............................................46 
Figure 33.  Polypropylene pellets after chopping ..........................................................................47 
Figure 34.  Melting temperature behavior of pure polypropylene and nanoclay (Cloisite 15A) 
added pellets...................................................................................................................................49 
Figure 35.  Melting temperature behavior of pure polypropylene and nanoclay (cloisite 30B) 
added pellets...................................................................................................................................49 
Figure 36.  Decomposition behavior of pure polypropylene and nanoclay (cloisite 15A) added 
pellets .............................................................................................................................................50 
x 
 
Figure 37.  Decomposition behavior of pure polypropylene and nanoclay  (Cloisite 30B) added 
pellets .............................................................................................................................................50 
Figure 38.  Decomposition behavior of pure polypropylene and nanoclay (Cloisite 15A) added 
monofilaments................................................................................................................................52 
Figure 39.  Decomposition behavior of pure polypropylene and nanoclay (Cloisite 30B) added 
monofilaments................................................................................................................................53 
Figure 40.  Stress-strain behavior of Cloisite 15A added composite and pure polypropylene 
monofilaments................................................................................................................................54 
Figure 41.  Stress-strain behavior of Cloisite 30B added composite and pure polypropylene 
monofilaments................................................................................................................................54 
Figure 42.  SEM surface view of: a) P-A-5, b) P-A-10, c) P-A, d) P-A-15 ..................................55 
Figure 43.  SEM surface view of: a) P-B-5, b) P-B-10, c) P-B, d) P-B-15 ...................................56 
Figure 44.  Particle size distribution of 0.5% Cloisite 15A added composite monofilament ........58 
Figure 45.  Particle size distribution of 0.5% Cloisite 30B added composite monofilament ........58 
Figure 46.  World polypropylene demand by region in 2009 ........................................................63 
 
 
1 
 
CHAPTER 1 
INTRODUCTION AND BACKGROUND 
Polymer-layered silicate (PLS) nanocomposites have been investigated by academic and 
industrial researches in recent years because the final composites often provide a desired 
enhancement of mechanical, molecular barrier, thermal, flame retardant, corrosion protection 
properties and/or other properties relative to the original polymer matrix, even at very low clay 
contents [1-8]. Nanoparticles may dominate the behavior of materials because of their sizes, 
nanoscale dimensions, and relatively huge surface areas per unit weight. Carbon nanotubes, 
montmorillonite type clays and bimolecules such as protein and DNA are used in many 
nanostructures [3, 9]. 
Polymeric properties can be improved even at low loading without negative effects on 
density, transparency and processability. Basically, nanoparticles are dispersed in a polymer 
matrix at low amounts, most of the time less than 6% by weight [10]. The conditions for 
successful reinforcement and good properties are the homogeneous distribution and dispersion of 
the reinforcing components, high aspect ratio of the nanolevel fillers, and good adhesion between 
polymer matrix and fillers [11]. Many thermoplastic and thermosetting polymers with different 
polarities including polystyrene, polycaprolactone, polypropylene, poly(ethylene oxide), epoxy 
resin, polysiloxane and polyurethane can be used to form nanocomposite structures. The first 
commercial product of clay-based polymer nanocomposites was the timing belt cover made from
2 
 
PA6 nanocomposites by Toyota Motors in the early 1990s. This timing-belt cover exhibited good 
rigidity, excellent thermal stability and no wrap. It also saved weight by up to 25% [3].  
Twin and single screw extrusion machines are mainly used for filament and film 
manufacturing. Nanocomposite structures can be produced by extrusion machines because of 
their good mixing characteristic and processing efficiency compared to other methods. The 
features of the extruder and screw configuration are important to obtain good dispersion. Better 
dispersion may be achieved with longer residence times in the extruder [12]. In some cases, 
having a higher melt viscosity is useful in obtaining dispersion, because of the higher stresses 
that can be enforced on the nanoparticles [8]. Other parameters such as barrel and die 
temperatures, draw-down ratio, and heater temperature can be adjusted for better dispersion. 
Correct settings of these parameters can change the reinforcing effect, agglomeration of particles, 
and synergistic effect of nanoparticles. 
Polypropylene/nanoclay nanocomposites are being investigated in recent years. 
Polypropylene and nanoclays have advantages to be used in forming of nanocomposite 
structures. Nanoclays have high aspect ratios and plate morphology. Their low cost and 
environmental friendly characteristics make them very attractive. On the other hand, 
polypropylene is one of the most widely used polyolefin because of the low cost, low density, 
high thermal stability and easy processibility. For example, Sharma and Nayak [1] obtained 95% 
enhancement in tensile strength and 152% in tensile modulus of clay modified polypropylene. 
Shariatpanahi et al. [13] observed improvement in tensile modulus and impact strength by 15 and 
22%, respectively, with the addition of montmorillonite clay into polypropylene matrix via direct 
melt mixing method. Baniasadi et al. [14] reported improvement of thermomechanical properties 
of nanocomposites by introducing small amount of clay into polymer matrix. Zhang et al. [15] 
3 
 
successfully prepared polypropylene (PP)/organomontmorillonite (OMMT) nanocomposites via 
melt intercalation by using conventional twin screw extrusion technique, and dispersed 
organoclay layers were observed in the PP resin at the nanometer level. Wenyi et al. [16] 
investigated the dispersion of organo-montmorillonite (Org-MMT) in polypropylene matrix and 
observed an increase in melting and crystallinity point of the nanocomposites. Joshi et al. [17] 
characterized monofilaments which contain polypropylene/clay, and obtained improved tensile 
strength, modulus, thermal stability, and reduced elongation at break. Horrocks et al [18] 
successfully produced polypropylene filaments that contained Cloisite 20A nanoclay, and 
observed that filament modulus was increased to some degree. In addition, Kumar et al. [4] 
added small carbon fibers to the nanoclay filled PA66/PP and extruded them in order to improve 
mechanical properties. 
. 
1. Nanocomposite Structures 
A nanocomposite can be defined as a particle-filled polymer which has at least one 
dimension of dispersed particles in the nanometer range [19]. We can classify the 
nanocomposites according to the dimension ranges of the dispersed particles. When we mention 
the three dimensions which are all in the order of nanometers, we are talking about 
isodimensional nanoparticles, such as spherical silica nanoparticles, semiconductor nanoclusters, 
and others [20, 21]. Carbon nanotubes or cellulose whiskers can be classified separately in which 
two dimensions are in nanometer scale, and the third one is larger while forming an elongated 
structure [22, 23]. In the last group, one dimensional fillers exist which are typically a few 
nanometers thick and a few thousand nanometers long. Polymer-layered crystal or clay 
nanocomposite is the general name of this group [24]. 
4 
 
        Nanocomposites cannot be formed only by physical mixing of the polymer and inorganic 
materials. The problem is the polymer blends; most of the time immiscible systems cause poor 
mechanical attraction and particle agglomeration between the polymer and inorganic materials. 
Therefore, phase separated composite, which is similar to the traditional microcomposites, is 
obtained when the polymer is not capable to intercalate between silicate sheets [3, 20]. The 
polymer layered silicate nanocomposites are based on separation and dispersion of the clay 
platelets in polymer matrix, and this dispersion range goes from simple intercalation to complete 
exfoliation of the silicate layers [2, 3, 6, 12, 17]. Clay layers are placed within the structure and 
they exist as particles containing tactoids at immiscible nanostructures (Figure 1(a)).  Clays are 
separated more at intercalated systems and penetration of the polymer chain may occur in the 
interlayer spacing (Figure 1 (b)).  Clay layers are separated individually and better dispersions 
are achieved in exfoliated nanostructures compared to the other two systems as shown in figure 
1(c) [25, 26]. However, it is very difficult to obtain full exfoliation due to poor affinity between 
nanofillers and polymer matrix [2, 27, 28]. There is a separation of less than 20?30 ? between 
the platelets in intercalation, but the polymer separates the clay platelets by 80?100 ? or more 
during exfoliation [3]. The exfoliated system is the main interest in nanocomposites because it 
maximizes polymer-clay interaction and makes the whole surface of layers available for the 
polymer. This helps to improve mechanical and thermal properties better than intercalated 
structures [3]. 
5 
 
         
(a)                                      (b)                                              (c) 
 
Figure 1.  Level of nanoclay dispersion: a) Immiscible Nanostructure, b) Intercalated 
Nanostructure, c) Exfoliated Nanostructure [2, 29] 
 
1.1. Layered Silicates 
 
Layered silicates are commonly used in nanocomposites and they are known as the 2:1 
phyllosilicates. Table 1 shows some common phyllosilicates. 
Table 1.  Chemical structure of phyllosilicates 
2:1 phyllosilicates                                                                            General Formula 
Montmorillonite  Mx(Al4-xMgx)Si8O20(OH)4 
Hectorite  Mx(Mg6-xLix)Si8O20(OH)4 
Saponite  MxMg6(Si8-xAlx)O20(OH)4 
M=monovalent cation; x=degree of isomorphous substitution (between 0.5 and 1.3) [6] 
 
One of the most widely used layered silicates (nanoclays) is montmorillonite as shown at 
Figure 2. It has two silicate tetrahedral layers sandwiching an inner octahedral layer which 
Clay platelets 
Polymer 
6 
 
consist of either alumina or magnesia [2, 26]. The duty of the Na+ is to counterbalance the Al or 
Mg for generation of negative charge in the platelet. Montmorillonite has many platelets (layers), 
and there are Van der Waals forces between these layers [29]. The gaps between the layers are 
called interlayer or gallery. For example, the X-ray d-spacing of completely dry sodium 
montmorillonite is 0.96 nm while the platelet itself is about 0.94 nm thick [2]. The initial 
interlayer space is about 3.15 nm for Cloisite 15A and 1.85 nm for Cloisite 30B [12]. 
 
 
Figure 2.  Structure of a 2:1 layered silicate [3] 
 
Montmorillonite is in powder form with a mean particle size of about 8?m, and in each 
particle of powder there are more than 3000 platelets [30]. The thickness of each layer is around 
1nm, and the length of these layers can vary from 300? to several microns [31], i.e., it has high 
aspect ratio.  
7 
 
Generally, there are two main considerations for polymer/layered silicate 
nanocomposites. The first one is dispersion of silicate particles into individual layers. The second 
is the ability of improving the surface chemistry through ion exchange reactions with organic and 
inorganic cations [32]. Pretreatment of clays using ammonium salts or alkyl phosphonium makes 
the clays organophilic; the modified clays are called organoclays [25, 33]. Figure 3 shows the 
exchange process between alkylammonium ions and metallic cations. After exchanging the ions, 
surface energy of inorganic host decreases and wetting properties of polymer matrix are 
improved. Larger interlayer spacing is obtained as a result [34]. 
 
 
Figure 3. Cation-exchange process between alkylammonium ions and metallic cations  [34]. 
 
Most of the time, polymer/clay nanocomposites have the combination of good 
processibility characteristic of the polymers, and great physical properties of the clays such as 
mechanical, thermal, and electrical properties [35-37]. As mentioned before, polypropylene-
nanoclay nanocomposites are interesting for industrial applications because PP is one of the most 
widely used thermoplastic polymer and nanoclays are effective as filler materials [32]. However, 
8 
 
there are some difficulties to form these nanostructures. Nanoclays are known to be naturally 
hydrophilic while PP has no polar groups in its backbone and therefore, it is a hydrophobic 
polymer [10, 38]. Most of the time, poor interfacial bonding between the PP matrix and clay 
surface is obtained with low level of dispersion of the clay plates [39]. Compatabilizers (PP-g-
MA) are used to improve intercalation/exfoliation of the organoclay and maximize its interfacial 
contact with polymer matrix [1, 25].  PP-MA has polar groups (-OH, COOH) which increases 
the polarity of the polypropylene [40]. They help to bond the clay and PP together with hydrogen 
bonds between the polar carboxylic group of PP-MA and oxygen or hydroxyl group in silicates 
[41]. The interlayer spacing of the montmorillonite increases, and interaction between the silicate 
layers gets weaker.  Dispersion of silicate layers dispersion in polymer matrix via PP-MA is 
illustrated in Figure 4. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
9 
 
 
 
 
 
 
                                    
                               
                             
 
Figure 4.  Dispersion of silicate layers in polymer matrix via PP-MA [40] 
 
 
PP-MA 
Silicate layers of 
Montmorillonite 
+ Maleic 
Anhydride 
Group 
+ 
Polymer 
10 
 
 
1.2. Nanoparticle Dispersion 
 
There are different techniques to disperse nanofillers at nanoscales in a polymer matrix. 
1.2.1. In situ polymerization 
In situ polymerization was the first method used to synthesize polymer?clay 
nanocomposites based on polyamide 6 [3]. In this technique, the layered silicate is swollen 
within the liquid monomer (or a monomer solution) so as the polymer formation can occur in 
between the intercalated sheets [3, 6, 24]. Mostly, the nanoparticles are pretreated with a 
chemical agent to improve their compatibility with the polymer matrix [8]. 
 
1.2.2. Solution blending  
 
There are weak forces that stack the layers together, and they can be easily dispersed in 
an adequate solvent.  It involves dissolution of polymers in adequate solvent with nanoscale 
particles and evaporation of solvent or precipitation [3, 24]. The final structure may be 
intercalated or exfoliated depending on the interaction between filler and polymer matrix. 
 
1.2.3. Melt intercalation  
The layered silicate is blended with the polymer matrix in the molten state. If there is 
sufficient affinity between polymer matrix and filler, either an intercalated or an exfoliated 
nanocomposite can be achieved [6]. Melt intercalation is the most widely used method for 
monofilament processing, and it is environmentally friendly due to lack of solvent during mixing 
or processing. It is compatible with the current industrial methods such as extrusion and injection 
11 
 
molding, and also allows polymer processing that is not suitable for in situ polymerization or 
solution intercalation [26]. 
 
1.2.4. Template synthesis 
  Clay minerals are synthesized within the polymer matrix, using an aqueous solution (or 
gel) containing the polymer and silicate building blocks [3, 6, 24]. 
The montmorillonite intercalated with the PP-MA oligomers have good contacts with PP 
under strong shear [33, 42]. Stacked platelets can be broken into smaller pieces and the interlayer 
spacing increases during extrusion process (Figure 5). The increase in interlayer space helps for 
better dispersion and distribution of the nanoclays in polymer matrix.  
 
                        
 
 
 
 
      
 
 
                                 
 
 
Figure 5.  Organoclay dispersion and exfoliation during melt processing [6] 
Smaller Nanoclay Particles 
Shear 
Polymer 
Shear Shear 
Shear 
Nanoclay particles 
12 
 
Some of the polypropylene monofilament application areas include nets and fabrics for 
agricultural end uses, geotextiles,  sun breakers, sun blinds, shade nets, wind walls, safety nets, 
swimming pool covers, reinforcements in various coated products (such as plastics, and papers), 
filtration, carpeting, packaging, concrete reinforcement, and medical suture.
13 
 
CHAPTER 2 
MANUFACTURING AND CHARACTERIZATION OF PP/CLAY MONOFILAMENTS 
 
1.  Materials  
- Polypropylene copolymer 30 Melt 2 Izod natural with melt flow index (MFI) of 30 
g/10 min, and density of 0.91 g/cm3.  
- Cloisite 15A as nanoclay which was already modified with a quaternary ammonium 
salt. 
- Cloisite 30B as nanoclay which was already modified with a quaternary ammonium 
salt. 
-  Polybond 3200 (PP grafted with malefic anhydride; 1.0 weight % maleic anhydride 
level). It has 115 g/10 min MFI, and 0.91 g/cm3 density. 
2.  Machines Used For Manufacturing 
All PP/Nanoclay monofilaments were prepared with melt intercalation method using 
single screw and twin screw extruders. Extrusion machines for the monofilament manufacturing 
are shown at Figure 6 and 7.  
14 
 
 
Figure 6.  Single screw extrusion machine 
 
Figure 7.  Twin screw extrusion machine 
 
 
 
 
 
15 
 
2.1. Extrusion Machine 
The common explanation of the extrusion is a process which plastic resins or pellets are 
used in a heated barrel or chamber, and carried along by a screw to the die which gives final 
shape of the products [43, 44]. Extrusion is one of the most efficient, most significant 
technologies of polymer processing. Almost 40% of polymer products are produced with 
extrusion. Extrusion has some advantages over other plastic processing techniques such as 
continuity, low cost, efficiency, broad raw material range, high production volume, and efficient 
mixing [45]. 
The first extruders were used in the food industry by bakers for noodle production. H. 
Bewley and R. A. Brooman made the first light industrial application in 1845, but the first 
extruder was patented by M. Grey [43]. These extruders were mainly used in the rubber industry.  
Today, modern extruders are not very different than the old ones, but there have been a 
lot of changes at the geometry of the screws. Mainly, there are five considerations in an extrusion 
process for highly quality products: 
- Appropriate polymer melt temperature 
- Uniform/stable melt temperature 
- Accurate melt pressure in the die 
- Uniform/stable melt pressure in the die 
- Well-mixed product [44].  
 
 
 
 
16 
 
2.1.1. Extruder Parts 
Typical extruder mainly consists of hopper, barrel, screw, heaters, breaker plates, die, and 
melt pump (Figure 8). 
 
Figure 8.  Longitudinal cross-section of an extruder [46] 
 
2.1.1.1. Screw 
Extruder screw is connected through a trust bearing and rotates inside the barrel. The 
screw has important functions such as removing the pellets from the hopper, providing 
mechanical energy as part of the melting process, mixing pellets and additives, and generating 
pressure to push the melted polymer out of the die [45]. Figure 9 shows the main components of 
a single screw. 
 
Figure 9.  Schematic of a typical single screw [47] 
17 
 
 
Figure 10.  A typical twin screw [48] 
 
Twin screws provide better melting, mixing, and conveying in a shorter machine length 
than a single screw machine [49]. They also have ability to process the materials which are 
difficult to feed [50]. Figure 10 shows a twin screw. 
 
2.1.1.2. Barrel 
Barrel is expected to endure against high pressure and temperature. The screw is located 
inside the barrel. The barrel is made by hardened steel and lined with wear and corrosion 
resistant metal [45, 47].  
2.1.1.3. Die 
The die which determines the extruded plastic?s cross sectional area is located at the end 
of heating zones (Figure 11). Monofilament diameters are affected by die diameter, screw speed, 
and the distance between die and water bath. Melted polymer falls down to the water with 
gravity effect, and solidifies there when contacts with water. If the distance between the die and 
water bath is short monofilaments will be thicker. When screw speed is increased monofilament 
diameter will be thicker because more polymers will be pushed to the die.  
18 
 
 
Figure 11.  Single screw extruder die 
2.1.1.4. Melt Pump 
Most of the extruders have a melt pump which is used to prevent any pressure changes 
and transfer the melted polymer through the die. There are some cases that using gear pump 
provides advantages: 
? Poor pressure-generating capability extruders (e.g., co-rotating twin screws, multi-stage 
vented extruders, etc.) 
? When output stability is required to be better than 1%, i.e., in close tolerance extrusion 
(e.g., fiber spinning, cable extrusion, medical tubing, co-extrusion, etc.)[51]. 
19 
 
 
Figure 12.  Operation of melt pump 
 
Figure 12 shows a melt pump that contains two counter-rotating, intermeshing gears 
which produce a positive volumetric displacement of the melt. The molten polymer is used as 
lubricant for the bearings during process, and clearances are important at high pressure to avoid 
leakage. The melt pump also makes it possible for the extruder to run at lower head pressure, and 
this increases the specific output rate and decreases the melt temperature.  A lower melt 
temperature is reduction of the possibility of thermal degradation during the extrusion process 
[52]. 
 
2.1.1.5. Breaker Plate 
Breaker plates are used to prevent dusts, solids, or any foreign particles to pass through 
the die.  
Inlet  Outlet 
20 
 
 
Figure 13.  Breaker Plate 
 
 
2.1.2. Processing 
2.1.2.1. Row Material Blending and Mixing 
The feedstock is mostly used in pelletized form, but sometimes powder form is also used 
for good mixing with powder additives. These additives can be thermal stabilizers, nanofillers 
such as nanoclay or carbon nanotubes, UV stabilizers, plasticizers, and flame retardants. The best 
way to combine raw materials is mixing them prior to feeding into the extruder hopper. Some  
factors to be considered for material mixing are; 
- Pellets and powder separation 
- Appropriate mixing 
- Particle size of the additives 
- Uniform distribution of powders at low concentration [44]. 
Manufacturers want to increase the flow rate, decrease energy cost, and have minimum 
irregularities during extrusion process. These irregularities are classified in two groups: 
- Surface irregularities which happen because of constant shear stress perfunctory of 
extrusion temperature. Some types of surface irregularities are shark skin and 
roughness. They affect the final product properties. 
- Flow irregularities which happen at unsteady flow conditions [53]. 
21 
 
 
2.1.2.2. Drying 
Some polymers need to be dried prior to extrusion to prevent polymer degradation. 
Nylon, polyester (PET and PBT), polycarbonates absorb moisture from the air [44]. Moisture 
may affect the molecular weight of these polymers, and result in poor polymer properties. The 
moisture in the polymer may change to steam and cause surface defects such as splay, holes or 
foamy product.  
 
2.1.2.3. Feeding Polymer to Extruder 
There are basically 4 ways to feed polymer to a single screw extruder; 
a) Flood Feeding 
The most common method is flood feeding (Figure 14); pellets or powders are placed 
directly in a hopper over the feed throat, and they are fed to the screw with gravity [44]. 
 
 
Figure 14.  Flood feeding 
 
 
 
22 
 
 
b) Starve Feeding 
Starve feeding is typically used in twin screw extrusion but can be employed in single 
screw extrusion as well (Figure 15) [44]. 
 
Figure 15.  Starve feeding 
 
c) Crammer Feeding 
 
Crammer feeding is a positive system that works well with low bulk density materials, 
materials that tend to bridge and hard to feed materials. A screw mechanism inside the crammer 
positively conveys material to the extruder as shown in Figure 16 [44]. 
 
 
Figure 16.  Crammer feeding [44] 
Crammer 
Extruder 
23 
 
d) Melt feeding 
 
Molten polymers can be also fed from one extruder to another extruder. Basically, the 
feeder extruder is shorter, and develops uniform pressure and polymer melt temperature for the 
die (Figure 17) [44]. 
 
 
Figure 17.  Melt feeding 
2.1.2.4. Shaping and Drawing 
Shaping is the last step in the extruder. When the polymer molecules relax and re-
entangle at the end of the die, die swelling occurs as shown at Figure 18. Pullers (godets) have 
important role at this section (Figure 19). 
 
Figure 18.  Extrudate expansion [54] 
 
Feed 
24 
 
 
Figure 19.  Godets and heater units of the single screw extruder 
 
There must be a correlation between godets? speed and throughput rate to have the same 
dimensional product at the end of the process. Speed of the godets affects the molecular 
orientation of the polymers [44]. Molecular orientation can be increased or decreased by 
changing the draw-down ratio (Figure 20). Every polymer has a natural draw-down ratio, which 
changes the tensile and flexural properties [55]. Draw ratio can be calculated by the ratio of 
godets? speeds. Heaters can be used between two godets to have more uniform monofilaments.  
 
 
Figure 20.  Molecular orientation of fibers during stretching 
 
Draw-down ratio is one of the important considerations during monofilament 
manufacturing. Inaccurate ratios may results in diameter variations in the final product. Table 2 
shows the processing parameters to produce monofilaments in this study. 
25 
 
Table 2.  Parameter settings of monofilament processing 
Sample Barrel zone 
temperature 
?C (? F) 
Die zone 
temperature 
?C (? F) 
Motor 
speed 
(RPM) 
Melt pump 
speed 
(RPM) 
Heater 
temperature 
?C  (?F) 
Godet 
speeds 
(m/min) 
1 204 (400) 216 (420) 220 13 177 (350) 15-30 
2 204 (400) 216 (420) 220 13 177 (350) 15-45 
3 204 (400) 216 (420) 220 13 177 (350) 15-60 
4 204 (400) 216 (420) 220 13 177 (350) 15-90 
5 204 (400) 216 (420) 220 13 177 (350) 15-105 
 
Diameter variations were investigated and it was observed that uniformity was increased 
by increasing the draw-down ratio. Figure 21 shows the diameter changes by the draw-down 
ratio. It can be seen that when the draw-down ratio is 7, diameter variation is minimum. 
 
Figure 21.  Diameter changes with different draw-down ratios 
 
26 
 
Experiments were done to examine the diameter variations when different heater 
temperatures were applied at a draw-down ratio 7. Polypropylene copolymer 30 Melt 2 Izod 
natural with melt flow index (MFI) of 30 g/10 min, and density of 0.91 g/cm3 was used. Table 3 
shows parameter settings for monofilament processing for this purpose. 
 
Table 3.  Parameter settings of monofilament processing with different heater temperatures 
Sample Barrel zone 
temperature 
?C (?F) 
Die zone 
temperature 
?C  (?F) 
Motor 
speed 
(RPM) 
Melt pump 
speed 
(RPM) 
Heater 
temperature 
?C  (?F) 
Godet 
speeds 
(m/min) 
1 204 (400) 216 (420) 220 13 - 15-105 
2 204 (400) 216 (420) 220 13 177 (350) 15-105 
3 204 (400) 216 (420) 220 13 191 (375) 15-105 
4 204 (400) 216 (420) 220 13 204 (400) 15-105 
 
 
Four different monofilaments were manufactured with different heater temperatures. 
Then, diameters of the monofilaments were measured at every meter with microscopy. It can be 
seen in Table 4 that uniform monofilaments were obtained with low CV values. However, the 
monofilaments which were processed with heaters showed more uniform diameters compare to 
the ones manufactured without heater.  
 
 
 
27 
 
Table 4.  Diameter variation of different monofilaments 
Sample 1 Sample 2 Sample 3 Sample 4 
 
Distance 
(Meter) Diameter (?m) Diameter (?m) Diameter (?m) Diameter (?m) 
1 260.63 256.61 258.62 249.24 
2 253.93 245.89 254.6 254.6 
3 244.91 251.25 255.94 249.24 
4 256.61 248.57 249.91 250.58 
5        247.90 247.23 251.25 247.23 
6 253.93 247.9 253.26 250.58 
7 257.95 244.55 253.26 244.55 
8 253.26 249.91 253.26 243.21 
9 245.91 252.59 249.24 249.24 
10 249.91 249.91 260.63 255.94 
Mean 252.49 249.441 253.997 249.441 
C.V. (%) 2.07 1.39 1.42 1.57 
 
 
Tensile properties can be affected by draw-down ratio and heater temperatures. Higher 
draw-down ratios results in higher tensile properties due to better molecular orientation of the 
monofilaments. Lower draw-down ratios cause necking which produces nonuniform structures 
with low tensile properties. Figure 22 shows the tensile strength changes at different draw-down 
ratios.  
 
28 
 
 
Figure 22.  Tensile strength of monofilaments at different draw-down ratios 
 
Heaters may affect the tensile strength of monofilaments. Figure 23 reflects the tensile 
strength values obtained with different heater temperatures. Monofilaments which were 
processed with higher heater temperatures had more tensile strength. As mentioned before, 
heaters helped to get more uniform monofilaments, which may result in higher tensile properties 
of the final products. Besides, heating makes the drawing of the monofilaments more efficient 
because of providing chain relaxation of the molecules. 
 
Figure 23.  Tensile strength of monofilaments at different heater temperatures 
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5 6 7 8
Tensile
Strength
(MPa)
Draw-down ratio
305
310
315
320
325
330
335
340
90 110 130 150 170 190
Tensile Strength 
(MPa)
Heater Temperature ( ?C)
29 
 
 
2.1.2.5. Solidification and Cooling 
After the die, filaments move through a water bath and solidify there. Instead of water, air 
can be used for cooling as well. Water temperature can be adjusted according to the polymer 
type. Sharp cooling can affect crystalline properties of polymers. 
2.1.2.6. Winding  
This is the final step of the extrusion process. Drawn filaments are rolled up on bobbins 
at winder (Figure 24). The winder speed can be adjusted; however, it should not be more than the 
final godet?s speed. If it is higher, breakage may occur. 
 
Figure 24.  Winder section 
 
 
 
 
 
30 
 
 
2.1.3. Differences between Single and Twin Screw Extruders 
There are some differences between twin and single screw extruders (Table 50). For 
instance, better feeding, easier processing with hard-to-feed materials (powders, slippery 
materials, etc.), short residence time and a narrow residence time distribution [56]. 
 
Table 5.  Differences between single and twin screw extruders [56] 
 Single screw Twin screw 
Flow  type drag Near positive 
Residence time and distribution Medium/wide Low/narrow(useful for 
reaction) 
Effect of back pressure on output Reduces output Slight effect on output 
Shear in channel High (useful for stable 
polymers) 
Low (useful for PVC) 
Overall mixing Poor /medium Good (useful for 
compounding) 
Power absorption and heat 
generation 
 
High (may be adiabatic) Low (mainly conductive 
heating) 
Max. screw speed High( output limited by 
melting, stability, etc) 
Medium (limits output) 
Thrust capacity High Low (limit pressure) 
Mechanical construction Robust, simple Complicated 
First cost Moderate High 
 
 
 
 
31 
 
3. Preparation of PP/Nanoclay Composite Monofilaments 
First, monofilaments were produced with the single screw extruder. Then, twin and single 
screw extruders were used in sequence to have more efficient processing. 
3.1. By Using Single Screw Extruder 
Different amounts of nanoclay (Cloisite 15A) and compatabilizer (Polybond 3200) were 
used to form composite monofilaments by the single screw extruder. Attempts to produce 
polypropylene/nanoclay composite monofilaments without compatabilizer were unsuccessful. 
Table 6 shows the master batches and sample codes.  
 
Table 6.  Sample codes and blends of master batches for single screw extruder 
 
                Sample Code          Clay Loading (%)            Compatabilizer Loading (%)  
        PP  - - 
P1-C10 1% 10% 
P1-C15 1% 15% 
P1-C20 1% 20% 
P2-C10 2% 10% 
P2-C15 2% 15% 
P2-C20 2% 20% 
P3-C10 3% 10% 
P3-C15 3% 15% 
P3-C20 3% 20% 
 
Cloisite 15A was dried in a vacuum oven at 65 ?C for 12 hours prior to manufacturing. 
Pure polypropylene pellets, Cloisite 15A, and Polybond 3200 were mixed manually before 
processing. Processing temperatures are given in Table 7. 
32 
 
Table 7.  Temperature settings of the single screw extruder 
 
 
 
 
 
 
 
 
The extruder screw speed was 100 rpm, and melt pump speed was set to 13rpm. A draw-
down ratio of 7 was applied to the monofilaments. After the water tank, air was blown on the 
monofilaments to dry them before drawing section. After the drawing, all monofilaments, except 
pure polypropylene, were chopped and reextruded to obtain better dispersion and distribution of 
the nanoclays in polymer matrix. 
3.2. By Using Twin and Single Screw Extruders in Sequence 
 
Twin screw extruders are mainly used for mixing different components. They produce 
better shearing effect on nanoclays which means that more separation of nanoclay layers may 
occur. In addition, better distribution and dispersion may be obtained compared to single screw 
extruders. 
Heating Zones Temperature  ?C (?F) 
Barrel zone-1 204 (400) 
Barrel zone-2 204 (400) 
Barrel zone-3 204 (400) 
Barrel zone-4 204 (400) 
Die zone-1 218 (425) 
Die zone-2 218 (425) 
Die zone-3 218 (425) 
Die zone-4 218 (425) 
Die zone-5 218 (425) 
Die zone-6 218 (425) 
33 
 
Different types of nanoclays (Cloisite 15A and Cloisite 30B), and a compatabilizer 
(Polybond 3200) were used to form composite monofilaments. First, twin screw extrusion 
machine was used to make tape forms. Table 8 shows master batches and sample codes. 
Table 8.  Sample codes and blends of master batches for twin screw extruder 
Sample Code %15A %30B % Compatabilizer 
P-A-5 0.5 - 10 
P-A-10 1.0 - 10 
P-A-15 1.5 - 10 
P-A 1.0 - - 
P-B - 1.0 - 
P-B-5 - 0.5 10 
P-B-10 - 1.0 10 
P-B-15 - 1.5 10 
 
Cloisite 15A and 30B were dried in a vacuum oven at 65 ?C for 12 hours prior to 
manufacturing. Pure polypropylene pellets were fed to twin screw extruder with a pellet feeder 
(Figure 15). Nanoclay and compatabilizer were mixed prior to the processing, and then fed to the 
hopper while polypropylene pellets were being fed with the feeder. Extruder speed was set to 
200 rpm.  The temperature settings are given in Table 9. The tapes were cut with a chopper to 
have pellets that contained nanoclay and compatabilizer. These pellets were used in the single 
screw extruder to produce monofilaments. It was observed that manufacturing of monofilaments 
with the combination of twin and single screw extruder machines was easier than using only 
single screw extruder. Less breakage of monofilaments was noticed while drawing the 
34 
 
monofilaments. Besides, it was possible to produce monofilaments that do not have any 
compatabilizers (they could not be produced by using only single screw extruder). 
Table 9. Temperature settings of the twin screw extruder 
 
 
 
 
 
 
 
 
4.  Characterization 
 
The surface morphology of the pure and composite monofilaments was investigated by 
using Zeiss EVO 50VP scanning electron microscopy (SEM). Probe current was adjusted 
between 700-900 pA.  All specimens were coated with gold before the experiment. 
Basic crystalline structures of pure and composite monofilaments were analyzed using 
Bruker APEX single crystal X-ray diffractometer. Sample collections were made between 2? 
range of 5-40? with CuK?2 radiation at 40KV voltage, and 40 mA generators current. Scanning 
time was set to 750 seconds, and step size was 0.01?.  
Melting behavior and degree of crystallinity measurements were made by using Perkin-
Elmer DSC Q2000 instrument under nitrogen atmosphere. Sample sizes were between 5-10 mg. 
Samples were heated from 50 to 250 ?C at 10?C/min, and held there 2 minutes, then cooled to 
Heating Zones Temperature  (?C) 
Barrel zone-1 220 
Barrel zone-2 220 
Barrel zone-3 220 
Barrel zone-4 220 
Barrel zone-5 220 
Barrel zone-6 220 
Barrel zone-7 220 
35 
 
room temperature.  The crystallinity of the samples was calculated according to the following 
formula: 
Xc= g3057g3009g3057g3009
g3265g3265g3116
            (1)  
 g1986g1834 is the enthalpy of fusion of the sample (J/g) and g1986g1834g3017g3017g2868  is the enthalpy of fusion of 
completely crystalline PP (~209 J/g) [57]. 
Thermal stability of monofilaments was measured by using Perkin-Elmer TGA Q500 
instrument. The heating rate was 20?C/min for all samples, and the temperature range was 50-
600 ?C under atmospheric air. 
Nicolet 6700 FTIR spectrometer was used to characterize the molecular conformation of 
the pure and composite monofilaments. The number of each scan was 32, and experimental scan 
was set at 16.  
Samples were tested according to the ASTM D-3822-07 Standard Test Method for 
Tensile Properties of Single Textile Fibers with Instron 5565 Testing Machine. The diameter of 
each sample was measured with a microscope. Five tests were done for each sample and the 
average values were used for the evaluation of the properties. 
36 
 
CHAPTER 3 
RESULTS AND DISCUSSION 
 
1. Single Screw Extrusion Results 
 
1.1. SEM Microscopy  
The surface morphology of pure polypropylene and some of the polypropylene/nanoclay 
composite monofilaments are presented in Figure 25 (a-d). SEM images show the distribution of 
nanoclay particles along the monofilaments. P3-C10 sample has bigger particles compared to P1-
C10 and P2-C10. Agglomeration can be seen for P3-C10 sample due to low dispersion and 
distribution of nanoclay particles in the polymer matrix. Low shear effect of single screw 
extruder can also cause this agglomeration. P1-C10 and P2-C10 samples have almost the same 
level of nanoclay dispersion. The range of the particle size is between 700nm to 4 microns for 
P1-C10, and 3 to 10 microns for P2-C10. However, there are also smaller nanoscale particles 
which may help for reinforcement of the monofilaments. On the other hand, drawing of the 
monofilaments also helps with the distribution of nanoclay along the monofilament. In addition, 
sample P3-C10 could not be drawn well during processing compared to other samples due to 
agglomeration of the nanoclays. 
 
 
 
 
37 
 
      
(a)                                         (b) 
      
                    (c)       (d) 
Figure 25.  SEM images of surface views: (a) Pure PP Filament, (b) P1-C10, (c) P2-C10, 
 (d) P3-C10. 
 
38 
 
1.2. FTIR  
The FTIR spectrum of pure polypropylene and composite monofilaments is given in 
Figure 26. Si-O stretching (1005 cm-1) and Si-O bending (480 cm-1) can be observed for Cloisite 
15A. There are vibration of peaks between 900 and 1000 cm-1, and silicates and carboxyl groups 
might form bond in this range. However, all the peaks of composite monofilaments show similar 
characteristics compared to pure polypropylene monofilaments even if the clay loading is 
increased. This shows that there are weak bonds between nanoclays and polymer matrix due to 
agglomeration or lower dispersion of nanoclays. 
 
Figure 26.  FTIR spectra of pure and composite monofilaments 
 
 
 
 
 
 
39 
 
1.3. X-Ray Diffraction  
Figure 27 shows the X-ray diffraction of pure polypropylene monofilaments, P1-C10, P2-
C10 and P3-C10 drawn monofilaments. The results can give a general view about the 
nanocomposite structure. The different peaks may indicate the distribution of clay layers and d-
spacing which is the distance between the clay layers.  Polymer nanocomposite peaks often show 
shifting to lower 2? angle or larger d-spacing. Decrease or disappearance of characteristic peaks 
indicates the formation of intercalation or exfoliation nanostructures [58]. 
 
Figure 27.  XRD curves of pure polypropylene and composite monofilaments 
  
40 
 
Table 10 shows the diffraction peaks of samples at 2? angles. The results show that there 
is no significant change at peak characteristics of the samples. There is only little shifting at P3-
C10 sample, and agglomerated clay particles may cause this difference.  It can be concluded that 
addition of nanoclay did not affect basic crystal structure of the samples.  
Table 10.  Diffraction peaks of the samples at 2uni04E8 angle range 
Pure PP P1-C10 P2-C10 P3-C10 
14.11 14.04 14.07 13.97 
16.9 16.73 16.88 16.71 
18.52 18.44 18.48 18.35 
21.69 21.62 21.63 21.44 
 
1.4. Thermal Behavior  
 
Crystallization and melting behavior of the monofilaments with different nanoclay and 
compatabilizer loading are shown in Table 11.  Most of the filament properties depend on 
crystallinity, spherulites size, and the size of lamellar crystals. Polypropylene is a semicrystalline 
polymer; on the other hand, nanoclays are known as nucleating agents and accelerate the 
crystallization process [59]. It was observed that melting point of pure polypropylene decreased 
slightly with the addition of nanoclay as shown in Figure 28. Melting point decrease may suggest 
a reduction of lamellar size; probably the clay can prevent the growth of individual lamellae, and 
more lamellae are formed with smaller sizes [60].  
 
 
 
 
41 
 
Table 11.  Thermal and tensile results of composite monofilaments 
Samples Decomposition    
Temperature 
(?C) 
Tensile 
Strength 
(MPa) 
Elongation 
at Break 
(%) 
Tm(?C) Tc (?C) Xc (%) 
Pure PP 358.86 308.8 63.6 166.79 131.17 41.04 
P1-C10 368.32 289.1       52.0 166.60 130.73 42.48 
P2-C10 376.35    286.0       53.0 166.33 130.66 41.21 
P3-C10 393.95 276.1 54.7 165.78 130.80 41.95 
P1-C15 367.23 292.9 55.1 165.91 129.67 42.81 
P2-C15 375.77 282.6 52.5 165.39 129.61 43.81 
P3-C15 389.75 281.4 53.6 165.33 128.97 42.29 
P1-C20 367.61 294.7       63.0 166.12 128.35 43.56 
P2-C20 377.65 279.7 64.4 165.53 129.20 42.77 
P3-C20 389.23 273.6 64.2 165.65 127.73 42.69 
PP-MA 359.15 - - 162.36 112.61 42.40 
42 
 
 
 Figure 28.  Melting behavior of pure and composite polypropylene monofilaments 
Crystallization temperature (Tc) decreased slightly with the presence of nanoclay in the 
system. This also indicates the nucleating affect of nanoclays in crystallization of polypropylene. 
Addition of compatabilizer may also cause this reduction because of lower crystallization 
temperature (112.61 ?C). The degree of crystallinity (Xc) was calculated according to the 
equation (1), and an increase (41.04 % to 43.81%) was observed with the addition of nanoclay. It 
was also observed that Xc increased by increasing compatabilizer amount in composite 
monofilaments. 
Nanoclays are known as good heat insulators due to their good thermal resistance. 
Nanoclays can prevent the penetration of oxygen, and provide slower decomposition. TGA 
results are given in Table 11. The results show that addition of nanoclay increased 
decomposition temperature of the composite monofilaments compared to pure polypropylene 
43 
 
monofilaments. Figure 29 shows the comparison of pure and composite monofilaments during 
decomposition. Their onset temperatures are similar; after 300 ?C, they start to lose their weight 
under temperature. Pure polypropylene shows rapid decrease of weight compared to composite 
monofilaments, and decomposes at 358.86 ?C.  The decomposition temperatures in the Table are 
the means of four samples? decomposition temperature for each monofilament. Figure 30 shows 
how to determine the decomposition temperature for one of the pure polypropylene 
monofilaments with the TGA instrument. 
 
Figure 29.  Decomposition behavior of pure and composite polypropylene monofilaments at 
different nanoclay loadings 
44 
 
 
Figure 30.  Determination of pure polypropylene monofilament?s decomposition temperature 
Figure 32 shows the effect of compatabilizer on decomposition behavior: all the samples 
with compatabilizers have higher decomposition temperature than pure polypropylene 
monofilament. However, the composite monofilaments have almost the same behavior which 
indicates that amount of compatabilizer may not have any significant effect on decomposition. 
The decomposition temperature of the compatabilizer (359.15 ?C) is comparable to that of pure 
polypropylene (358.86 ?C). 
45 
 
 
Figure 31.  Decomposition behavior of pure and composite polypropylene monofilaments at 
different compatabilizer loadings 
 
1.5. Mechanical Behaviors  
Table 11 shows the tensile properties of pure and composite monofilaments. It was 
observed that addition of the nanoclay caused lower tensile properties. The reduction is almost 
10 % at 3 % clay loading. Higher nanoclay containing samples showed more reduction compared 
to the lower ones. SEM results also indicate some agglomeration in the monofilaments. These 
agglomerated particles, which are in micron sizes, can reduce interaction between nanoclay and 
polymer matrix, and the result will be interfacial debonding under load. Besides, these particles 
can cause voids and act as a crack initiator under the load. Figure 32 shows the decrease in 
tensile stress of the pure and composite monofilaments. 
 
46 
 
Nanoclay particles are stiff materials with no elongation properties; therefore addition of 
these particles can lower elongation behavior of the monofilaments. Elongation at break values 
decreased in the presence of nanoclays except at 20% compatabilizer content as shown in Table 
11. Samples containing 20% compatabilizer showed higher elongation properties compared to 
10% and 15% ones. Compatabilizer might have contributed to the elongation values after certain 
amount of loading at composite monofilament manufacturing. 
 
Figure 32.  Tensile behavior of pure and composite monofilaments 
 
 
 
 
 
 
250
260
270
280
290
300
310
320
Pure PP P1-C10 P2-C10 P3-C10 P1-C15 P2-C15 P3-C15 P1-C20 P2C20 P3C20
Str
ess
  (M
Pa)
Samples
47 
 
2. Twin and Single Screw Extruder Results 
 
2.1. Thermal Behavior of Pellets 
First, the pellets (Figure 33), which were produced with the twin screw extruder, were 
analyzed. Table 12 shows some of the thermal properties of these pellets. It can be seen that 
melting temperature of the pellets decreased slightly by addition of nanoclay particles except P-
A and P-B which do not contain any compatabilizers (Figures 34 and 35). As mentioned before, 
nucleating agent effect of nanoclay may be the reason for this small change.  Crystallization 
temperature (Tc) of nanoclay contained pellets mostly showed reduction. However, pellets P-A 
and P-B had higher Tc than other pellets. This may be due to not having any compatabilizer in 
the system. The degree of crystallinity (Xc) was calculated according to the equation (1), and 
lower values were obtained for composite monofilaments except P-A-15, compared to the pure 
polypropylene pellets. 
 
 
Figure 33.  Polypropylene pellets after chopping 
 
 
48 
 
Table 12.  Thermal behavior of pure polypropylene and nanoclay added pellets 
 
Sample code Melting 
temperature (?C) 
Decomposition 
temperature (?C) 
Tc (?C) % Xc 
PP 165.08 358.86 131.69 % 37.99 
P-A-5 163.93 421.42 130.18 %36.84 
P-A-10 164.52 425.75 130.68 %37.42 
P-A-15 164.82 430.44 131.21 % 39.08 
P-A 165.34 412.19 132.17 % 37.54 
P-B 165.52 409.10 132.21 % 36.14 
P-B-5 164.80 410.41 130.74 % 36.69 
P-B-10 165.07 417.37 130.55 %35.55 
P-B-15 164.62 429.68 130.70 %35.48 
 
 
49 
 
 
Figure 34.  Melting temperature behavior of pure polypropylene and nanoclay  
(Cloisite 15A) added pellets      
 
Figure 35.  Melting temperature behavior of pure polypropylene and nanoclay 
 (Cloisite 30B) added pellets 
50 
 
The decomposition temperature increased as shown in Figures 36 and 37 for the nanoclay 
added pellets. Cloisite 15A increased the decomposition temperature more than Cloisite 30B. 
This is probably due to better interaction occurred between Cloisite 15A and polypropylene 
polymer matrix compared to Cloisite 30B. 
 
Figure 36.  Decomposition behavior of pure polypropylene and nanoclay  
(Cloisite 15A) added pellets 
 
Figure 37.  Decomposition behavior of pure polypropylene and nanoclay  
(Cloisite 30B) added pellets 
51 
 
2.2. Mechanical and Thermal Behavior of the Composite Monofilaments 
 
After the pellets were chopped, they were used at single screw extruder to produce 
monofilament structures. Same machine settings were the same as in the previous experiments as 
can be seen in Table 7. Some of the mechanical and thermal test results are presented in Table 
13. 
 
Table 13.  Thermal and mechanical properties of the composite monofilaments 
 
 
 
 
 
 
 
 
 
 
 
 
Figures 38 and 39 indicate the decomposition behavior of different nanoclay added 
monofilaments. Decomposition temperatures of the monofilaments were increased by addition of 
nanoclay compared to pure polypropylene monofilaments. Nanoclays are known as good heat 
insulators and therefore may have contributed to the thermal stability of the system. They may 
also behave as a wall to prevent the products from escaping the matrix and lower oxygen 
Samples Decomposition      
temperature (?C) 
Tensile strength 
(MPa) 
Elongation at 
break 
(%) 
Pure PP 358.86 308.8 63.6 
P-A-5 398.88 296.8 39.7 
P-A-10 406.86 281.8 31.1 
P-A-15 425.73 272.5 27.0 
P-A 397.61 275.4 46.3 
P-B 394.12 258.4 36.3 
P-B-5 399.66 283.2 22.3 
P-B-10 404.15 272.4 39.2 
P-B-15 417.94 261.8 35.6 
52 
 
penetration into the matrix. Different nanoclay added composite monofilaments showed different 
characteristics. Cloisite 15A enhanced the decomposition temperatures more than Cloisite 30B. 
This is probably better due to distribution and dispersion of Cloisite 15A obtained along the 
monofilaments.  
 
 
Figure 38.  Decomposition behavior of pure polypropylene and nanoclay  
(Cloisite 15A) added monofilaments 
 
53 
 
 
Figure 39.  Decomposition behavior of pure polypropylene and nanoclay  
(Cloisite 30B) added monofilaments 
 
 
Figures 40 and 41 show the tensile stress-strain behavior of composite filaments 
compared to pure polypropylene monofilaments. The tensile strength values decreased compared 
to the pure polypropylene monofilaments for all composite samples. This is probably due to 
interfacial debonding and incoherence between nanoclay particles and polymer matrix. Addition 
of more nanoclay caused more decrease as seen in Table 13. Cloisite 30B caused more reduction 
in tensile properties compared to Cloisite 15A. More agglomeration of Cloisite 30B or bigger 
dispersed particles in the system may cause this difference. Elongation values decreased 
compared to the pure polypropylene monofilaments because nanoclay does not have any 
elongation properties. The results also show that samples P-A and P-B, which do not have any 
compatabilizer, had lower tensile strength compared to the samples with compatabilizers. This is 
54 
 
probably due to more agglomeration, and lower interaction between the polymer matrix and 
nanoclay. 
 
Figure 40.  Stress-strain behavior of Cloisite 15A added composite and pure 
polypropylene monofilaments 
 
 
Figure 41.  Stress-strain behavior of Cloisite 30B added composite and pure 
polypropylene monofilaments 
 
0
50
100
150
200
250
300
350
0 20 40 60 80
Tensile Stress 
(MPa)
Strain (%)
Pure PP
P-A-5
P-A-10
P-A-15
P-A
0
50
100
150
200
250
300
350
0 20 40 60 80
Tensile Stress 
(MPa)
Strain (%)
Pure PP
P-B-5
P-B-10
P-B-15
P-B
55 
 
2.3. SEM Results of Composite Monofilaments 
 
        
   (a)      (b) 
 
   
   (c)       (d) 
 
Figure 42.  SEM surface view of: a) P-A-5, b) P-A-10, c) P-A, d) P-A-15 
 
   (a)  
 
   (c)   
Figure 43.  SEM surface view of
 
 
56 
   
    (b) 
 
     (d) 
: a) P-B-5, b) P-B-10, c) P-B, d) P-B
 
 
-15 
57 
 
Figures 42 and 43 illustrate the SEM images of the composite monofilaments. Nanoclay 
distribution along the monofilaments seems quite uniform. It can be seen that monofilaments 
which contain 0.5% of nanoclay (sample P-A-5 and P-B-5) have smaller particles in their 
surfaces. Larger particles along the monofilament were achieved by addition of more nanoclay 
content (Fig 42-b-c-d and fig 43 b-c-d). These larger particles also caused lower tensile strength 
values compared to the smaller ones (Table 13). Probably bigger particles caused more voids and 
these voids made lower interaction between polymer chains. Figure 42 (b-c) and Figure 43 (b-c) 
can be used to evaluate the effect of compatabilizer on nanoclay distribution or particles sizes. 
Smaller particles were obtained along the monofilament (Figure 42-b) by addition of 
compatabilizer compared to the samples without any compatabilizer (Figure 42-c). The same 
result was also observed in Figure 43 (b-c). These results show that using compatabilizer helped 
for better dispersion of nanoclay particles. Particle sizes can be seen in Figures 44 and 45 for 
0.5% nanoclay added composite monofilaments. There are particles less than 500 nm, however; 
there are larger particles at micron sizes (almost 3-4 microns in same monofilaments). These 
larger particles were formed probably by agglomeration of nanoclay layers during processing. 
Bigger particle sizes were achieved for monofilaments that contain Cloisite 30B; this might be 
the reason why monofilaments that contain Cloisite 30B have lower tensile strength than the 
ones with Cloisite 15A. 
 
 
58 
 
 
Figure 44.  Particle size distribution of 0.5% Cloisite 15A added composite monofilament 
 
 
Figure 45.  Particle size distribution of 0.5% Cloisite 30B added composite monofilament
59 
 
CHAPTER 4 
NANOCLAY AND POLYPROPYLENE MARKETS 
 
1.  Nanocomposite Market 
Nanocomposite structures have been used at many industrial applications in recent years. 
Clay nanocomposites are the biggest market among all other nanocomposites (Table 14). Global 
consumption of nanocomposites has increased rapidly, reaching 23 million pounds in 2005, with 
an estimated value of $252 million. By 2011, it is expected to reach almost 95 million pounds 
worth some $857 million (Table 15) [61]. 
Table 14.  Nanocomposite consumption by % (2005-2011) [61] 
Year Clay nanocomposites Metal and metal oxide 
nanocomposites 
Carbon nanotube 
composites 
2005 24% 19% 15% 
2011 44% 20% 11.5% 
 
Table 15.  Global consumption of nanocomposites (2005-2011) [61] 
 
The main nanocomposite applications areas were automotive parts, energy, and 
packaging in 2005, with market shares of 29%, 28%, and 19%, respectively. Other application 
areas were coatings (14%) and ESD (Electrostatic discharge) (8%) in 2005.  
Year Amount kg-millions (lb-millions) Value ($ millions) 
2005 10.45            (23) 252 
2011 43.18           (95) 857 
60 
 
It is expected that packaging will be the leader in nanocomposite applications with over 
28% of the market by 2011. Energy applications will be in second place with more than 26% of 
the market, and automotive applications will be the third-largest application with over 15% of 
the market, followed by coatings with 14% in 2011 [61]. 
 
2. Polypropylene Market 
There was an increase in chemical fiber production compared to 2006 by 3.5 million tons 
or 8%, and to become 48.0 million tons in 2007. However, it decreased by 2.2 million tons or 6% 
to become 45.8 million tons in 2008. This increase occurred all around the world except China 
[62]. Table 16 shows chemical fiber production in 2007 around the world. 
Table16.  World chemical fiber production in 2007 [63] 
Types of fibers 
and threads 
Production, thousands of tons 2007/2006?% 
Complex fiber Stable fiber and twist Total 
Synthetic 23848 16536 40374 +7.9 
Polyester 18253 12416 30670 +11.7 
Polyamide 3633 353 3986 -1.1 
Polypropylene 1543 1315 2858 -4.4 
Polyacrylonitrile - 2376 2376 -4.9 
Other 420 66 468 +12.6 
Cellulose 440 3273 3712 +9.0 
Total 24288 19799 44037 +8.0 
 
 
61 
 
Table 17 shows global production of the most widely used synthetic fibers according to 
their manufacturing origins in 2007 and 2008. China is the biggest producer among all the 
countries. USA is also one of the biggest manufacturers with 1.2 million metric tons follows by 
India and Taiwan. 
Table 17.  Global production of synthetic fibers (1,000/kg tons) [64] 
           Polyester Polyolefins Polyamide 
 2007 2008 % 2007 2008 % 2007 2008 % 
W. Europe 677 566 -16 1,590 566 -11 451 415 -8 
Turkey 401 339 -15 624 339 -8 51 41 -20 
E. Europe 272 266 -2 190 266 -2 166 154 -7 
USA 1,240 1,060 -15 1,298 1,060 -14 937 741 -21 
Canada  - - - 86 73 -15 143 122 -15 
Mexico 149 112 -25 87 81 -7 43 29 -33 
S. America 311 273 -12 322 312 -3 104 96 -8 
PR China  19,251 20,046 +4 1,053 997 -5 1,007 1,083 +8 
India 2,272 2,090 -8 114 112 -2 95 90 -5 
Taiwan 1,813 1,522 -16 171 158 -8 408 302 -26 
Korea 1,245 1,157 -7 129 121 -6 145 131 -10 
Japan 465 435 -6 179 176 -2 122 114 -7 
Other Asia 2,709 2,536 -6 424 394 -7 145 131 -10 
Others 290 248 -14 502 496 -1 76 63 -17 
Total 31,095 30,065 -2 6,467 5,939 -8 3,891 3,512 -10 
62 
 
Table 18 reflects the global polyolefin fibers (polyethylene and polypropylene) 
production in 2008.  
Table 18.  Global production of polyolefin fibers (2008) [64] 
 Yarns Staple  Fibers Tapes Total 
1000 
 metric tons  
% 1000 
metric tons 
% 1000 
 metric tons 
% 1000 
 metric tons 
% 
W. Europe     678 -10 441 -13 229 -9 1,418 -11 
Turkey 142 -16 31 -18 125 -2 298 -8 
E. Europe 53 ?0 44 -2 91 -1 187 -2 
USA 611 -14 221 -17 284 -11 1,116 -14 
Canada 28 -15 20 -13 25 -17 73 -15 
Mexico 39 -2 12 -20 31 -3 81 -7 
S. America 116 -5 36 -10 160 -1 312 -3 
Asia 804  181  973  1,958  
- PR China 499 -6 81 -10 417 -4 997 -5 
 - Taiwan 68 -7 12 -25 78 -5 158 -8 
- Japan 78 -4 53 ?0 45 ?0 176 -2 
- Korea 58 -8 15 -6 48 -4 121 -6 
- India 24 -17 6 -14 81 +4 112 -2 
- Others 77 -13 14 -12 304 -5 394 -7 
Africa 185 -3 58 -5 253 +1 496 -1 
Total 2,656 -9 1,044 -12 2,239 -5 5,939 -8 
 
In 2008, PP textile materials production was over 7 
the amount of natural and chemical fibers an
that world PP consumption should reach 50 million
2010. Products obtained by injection molding (the combined increase here is estimated at 
6.4%/year) and extrusion, will remain the fastest growing market for PP in 
of these two sectors is 90-95% of PP processing [6
Consumption of PP for extrusion (fibers, films, spunbond, yarn, etc.) in China is at 68% 
(app. 60% in the world average). Almost 2 million tons (25%) is used for woven textiles, 1.4 
million tons (17%) for biaxially oriented fi
Europe, North America, and Japan 50% of the PP is used for injection molding, %23 is used for 
fiber production, and 15% for films, 8% extruded articles, 2% blow mol
purposes [66]. 
Figure 46.  World polypropylene 
 
Africa/M.East
19 %
W.Europe
5 % 
S.America
19 %
N.America
63 
million tons which is almost 10% of 
d yarns manufactured in 2007 [65
 of tons at 80-85% utilization capacities in 
the future;
6].  
lms, and 1 million tons (12%) for rigid packing. In 
ding, and 2% for other 
demand by region in 2009 [67]
9 %
S.E.Asia
5 %
Indian
7 % 
3 %
C.Europe
]. It is expected 
 the share 
 
 
33 %
N.E.Asia
64 
 
Figure 46 shows the World polypropylene market, which indicates that Asia is still the 
biggest market (total 42%) and followed by N. America and W. Europe.
65 
 
 
 
 
 
 
CHAPTER 5 
 
CONCLUSIONS AND FUTURE RECOMMENDATIONS 
 
Nanoclay added PP monofilament structures were successfully produced using twin and 
single screw extruder machines. Commercial nanoclays were used in this study. Draw-down 
ratio was set to 7. The formation of composite monofilament structures is affected by the amount 
of nanoclays, compatabilizers, and polarity of the polymer. It was more difficult to manufacture 
composite monofilaments with higher % nanoclay content because they caused more breakage 
during processing. There were mechanical and thermal changes in PP properties with the 
addition of nanoclays. Tensile strength decreased with the addition of nanoclays due to some 
agglomerated particles in the system. Decomposition temperature increased compared to pure 
polypropylene monofilament because of good heat insulation properties of nanoclays. Even if the 
tensile strength decreased, these monofilaments are still strong enough with higher 
decomposition temperatures and can be used in many industrial applications.  
 Proper mixing is very important to disperse nanoclays and compatabilizer uniformly 
during the process. More nanoclay dispersion can be achieved by increasing the space between 
clay layers and having higher shearing effect during processing. Monofilament production using 
both twin and single screw extruders was easier than only using single screw extruder. Less 
breakage occurred during processing because of having smaller nanoclay particles in the system.  
For the future work, different types of polymers, rather than polypropylene, can also be 
used, and they may provide different compatibility with nanoclays. Besides, different 
66 
 
nanoparticles such as carbon nanotubes or metal particles added composite monofilaments can 
be produced to achieve different final properties using twin and single screw extruders.
67 
 
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