Modification and characterization of liquefied biomass-based epoxy resin

Abstract

With the increasing requirement of biomass composites, people have paid more attention to the increasing use of synthetic adhesives, which require petroleum-based resources. Talking about petroleum-based resources, the increased demands for energy and concerns about energy security and climate change have created more and more attention on the alternative and renewable energy which will gradually share more portion of providing energy and then replace the significant role of petroleum-based resources. Synthetic glues (urea formaldehyde/ phenol formaldehyde adhesives are the most widely utilized binders used in the wood composites industry) used in most biomass composites often contain formaldehyde, which is a toxic chemical organic substance. Therefore, we planned to develop a novel adhesive without formaldehyde. The novel adhesive will be obtained by diglycidyl ether of biphenol A (EPON 828) reacted with bio-oil which was produced by the liquefaction of biomass. In this study, two kinds of biomass including switchgrass and southern pine wood were converted to bio-oil through a liquefaction process, and then bio-oil was utilized as a feedstock for epoxy resin synthesis. The aim of this study was to produce and characterize the liquefied biomass based epoxy resin. This study contained two main parts, one is using south pine wood as raw material for liquefaction and the other one is using switchgrass as raw material for liquefaction. And in each part, the procedure was composed of three steps, (1) liquefaction, (2) epoxidation and curing, and (3) characterization. Three different ratios of diglycidyl ether of biphenol A (EPON 828) to bio-oil (1:1, 1:2, 1:3 and 1:4) were investigated. Fourier transformiii infrared spectroscopy (FT-IR) analysis proved that epoxy functionality was successfully introduced into the liquefaction oil. To determine the cure properties and thermal stability of t adhesive/cellulose composite, thermal analysis using the differential scanning calorimetry (DSC), extraction tests and thermogravimetric analysis (TGA), which were conducted. In the first part, through the hydroxyl number tests and analyzed the residue contents, the optimal temperature and time for liquefaction were 220 oC and 2hrs. The optimal ratio of Epon 828 and southern pine wood based bio-oil was 1:1 which exhibited the highest properties in the tests of differential scanning calorimetry (DSC), extraction tests, Dynamic Mechanical analyzer (DMA) and thermogravimetric analysis (TGA). Compared to the experiment which was done by Thomas J. Robinson, he used bio-oil which used the same southern pine wood as raw material but through the pyrolysis procedure, the glass transition temperature was lower and the extraction results were also lower because the crosslink between the Epon 828 and bio-oil in this research was lower than they did. In the second part, through the hydroxyl number tests and analyzed the residue contents, the optimal temperature and time for liquefaction were 250 oC and 2hrs. The optimal ratio of Epon 828 and switchgrass based bio-oil was 1:1 which showed the highest properties in the tests of differential scanning calorimetry (DSC), extraction tests, Dynamic Mechanical analyzer (DMA) and thermogravimetric analysis (TGA).