Morphological Studies in Novel Liquid Rubber Modified Epoxies

The aim of this article is to present morphological studies on the tensile fractured specimens of novel liquid rubber obtained from the pyrolysis of scrap rubber. Such a study is crucial for gaining useful insight into the toughening mechanisms existing in rubber modified systems. A DGEBA based epoxy resin was first modified with varying concentrations (0-15 wt. %) of the liquid rubber. Dogbone shaped specimens of the cast plaques of the modified epoxies were tested under uniaxial tensile loading. The fracture surface was elucidated with the help of scanning electron microscopy (SEM). It was observed that biphasic morphology characterized with continuous epoxy phase and microvoids distributed throughout the epoxy domain develop in the modified epoxies. Cavitation of rubber particles under crack tip stresses is the reason behind development of these microvoids. The diameter of these microvoids were analyzed using the image analysis technique and was observed to increase with the concentration of rubber. Prevalent toughening mechanisms were visualized in the SEM micrographs necessary for the development of tougher and more ductile rubber modified epoxy systems.