Impact of water absorption on the creep performance of epoxy/microcrystalline cellulose composites

Abstract

Recently, considerable effort has been made to study cellulose/epoxy compos-ites. However, there is a gap when it comes to understanding the post-conditioning anomalous effect of moisture uptake on their mechanical anddynamic-mechanical properties, and on their creep behavior. In this work, upto 10.0 wt% microcrystalline cellulose (MCC) was incorporated into epoxyresin by simple mixing and sonication. Epoxy/MCC composites were fabri-cated by casting in rubber silicone molds, and rectangular and dog-bone testspecimens were produced. The moisture uptake, dynamic mechanical, chemi-cal, tensile, and creep behavior were evaluated. The incorporation of MCCincreased the water diffusion coefficient. The changes in storage modulus andglass transition temperature, combined with Fourier-transform infrared spec-troscopy analysis, evidenced that water sorption in epoxies causes both plasti-cization and additional resin crosslinking, although the latter is prevented bythe addition of MCC. The creep strain of the composites increased by 60% afterconditioning, indicating that plasticization induced by water sorption plays animportant role in the long-term properties of the composites.