Liquid rubber and silicon carbide nanofiber modified epoxy nanocomposites: Volume shrinkage, cure kinetics and properties

Abstract

A cyclic anhydride cured epoxy modified with carboxyl-terminated poly (butadiene-co-acrylonitrile) liquid rubber (CTBN) and SiC nanofibers was developed by two different mixing strategies. In mixing method 1, SiC nanofibers were sonicated in epoxy/CTBN mixture, while in mixing method 2 the sonicated epoxy/SiC mixture was mechanically mixed with CTBN. The effects of liquid rubber, SiC nanofiber and their mixing methods on the cure shrinkage and cure kinetics of an epoxy/nadic methyl anhydride system were studied using pressure–volume–temperature (PVT) analysis. The influence of SiC nanofiber and mixing method on cross-linking induced phase separation were investigated by means of optical microscopy. The glass transition temperature (Tg) and the thermal stability of nanocomposites were evaluated. The epoxy/SiC/CTBN nanocomposite prepared by method 2 exhibited enhanced Tg and thermal stability compared with neat epoxy and epoxy/CTBN blend. Moreover, improved impact strength was shown by epoxy/SiC/CTBN nanocomposites prepared by both methods, in comparison with epoxy/CTBN blend and epoxy/SiC nanocomposite. Additionally, fractographic analysis was carried out using scanning electron microscopy and a toughening mechanism for epoxy/SiC/CTBN nanocomposites was proposed.