Nanocomposites of in-situ polymerized cyclic butylene terephthalate and polyhedral oligomeric silsesquioaxanes

Abstract

Nanocomposites were prepared by in-situ polymerization of CBT®, a cyclic form of poly(butylene terephthalate) (PBT) and polyhedral oligomeric silsesquioxane (POSS®) with 2.5, 5 and 10 wt% POSS content. Three different types of POSS were used; two with reactive functional groups, Trisilanolphenyl POSS (TPOSS) and Glycidyl POSS (G-POSS) and one POSS type having non-reactive functionality, Isooctyl POSS (I-POSS). SEM analysis showed that I-POSS was finely dispersed at a nanoscale level within the CBT, whereas T-POSS and GPOSS formed agglomerates microscaled rather than nanoscaled. T-POSS hinders the polymerization reaction of the CBT, resulting in a poor consolidation of the composite. However, Glycidyl POSS was found to crosslink the CBT during polymerization, making it possible to alter the final material properties. All nanocomposites with 10 wt% POSS content showed a hindered cold crystallization and subsequently showed no melting peak of the formed polymer in a DSC scan.