Improve the compatibility and crystallization ability of polyhedral oligomeric silsesquioxanes and poly (ethylene terephthalate) by using transesterification method

In the present study, an investigation was conducted on the effects of polyhedral oligomeric silsesquioxane (POSS) on the mechanical, morphological, and thermal properties of PET-based nanocomposites. When the epoxy groups reacted with the PET end groups, the transesterification catalyst zinc acetylacetonate was introduced to facilitate the reaction between PET matrix and EPOSS. As clearly observed in the SEM image, 3 wt% POSS was added to PET matrix, the size of POSS particles was lower than 50 nm. As revealed from the EDX spectrum, the silicon signal was located in the EPOSS agglomerated particles and exhibited an even distribution in the entire PET matrix, which demonstrated a unique dispersion. Furthermore, it was reported that EPOSS exhibited nucleating agent performance, which suggested the higher temperature for melting crystallization (Up to 205.6°C while neat PET only reached 194.3°C). On the whole, EPOSS was revealed to act as a nucleating agent, whereas it could significantly facilitate the crystallization of PET by expediting the nucleation. Moreover, it could, to a certain extent, improve the mechanical properties of PET. These findings were attributable to the fact that PET and EPOSS exert a more comprehensive interface effect and a higher dispersion effect through the transesterification reaction.