Shape memory behavior and physical properties of peroxide X-linked LLDPE-C6/POSS and LLDPE-C8/POSS composites

Abstract

This study investigates the effect of branching of linear low-density polyethylene (LLDPE) and POSS types on thermal, mechanical, and rheological properties and shapes memory behavior of crosslinked LLDPE/POSS composites using different concentrations of peroxide (PRX). Shape memory polymers (SMPs) are intelligent materials that can recall their original shape from the temporary shape by applying an external stimulus such as temperature and pH when they are deformed. In this work, polyethylene (PE) copolymers of 1-octene (LLDPE C8) and 1-hexene (LLDPE C6) were utilized as the PE types. Di-tert-butyl cumyl peroxide was used as peroxide in 0.5, 1, 2, and 3 phr ratios. Octavinyl POSS (OvPOSS) and Octaisobutyl POSS (OibPOSS) were used as potent co-agents. The composites were prepared in an Xplore micro-compounder. The crosslinking was carried out using a hot press. The composites were characterized by performing rheological, thermal, and shape memory tests. It was found that the viscosity, storage modulus, and crosslinking density of composites increased in the presence of OvPOSS than that of composites including OibPOSS; however, the gelation times decreased as PRX amount increased. Plasticizing effect of OibPOSS was obtained from rheology test results. It was observed from shape memory tests that OibPOSS decreased shape recovery ratio whereas OvPOSS increased. When the PE types were compared, the highest shape memory results were obtained with LLDPE C6.