Development of Self-Degrading 3D Printed Polymer Matrix Composites via Moisture Absorption Evaluation

Abstract

Polymer degradation is a change in properties such as strength, color, shape, of a polymer or polymer-based material due to the effect of one or more environmental factors. These factors include heat, light or chemicals such as acids, alkalis and some salts. Polymer matrix composites exposed to moisture and high temperature environments can also experience several forms of degradation. Understanding how these composites degrade can help to develop degradable composites with the ability to self-degrade within a certain period of time. In this work, nylon, onyx (nylon reinforced with chopped carbon fiber) and polylactic acid (PLA) specimens were printed using a Markforged Mark Two and Maker Select v2 3D printers. The specimens were immersed in deionized (DI) water at 210C and 700C for different periods and characterized via moisture absorption and flexural testing. As expected, specimens exposed to higher temperatures displayed higher moisture absorption rates compared to specimens exposed to moisture at ambient temperature. Injection molded Nylon and PLA specimens were also tested and they displayed lower absorption rates compared to the 3D printed specimens. The specimens exhibited significant reduction in flexural strength and flexural modulus according to length of time immersed. Further characterization methods such as dynamic mechanical analysis (DMA), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) were also used. The factors investigated such as type of material, method of material production, absorption and desorption rates at different temperatures can be used as indices to develop degradation laws for polymer matrix composites.