Effect of short-chain architecture on the resulting thermal properties of polypropylene

Abstract

Polypropylene (PP) is a versatile commodity polymer with a plethora of potential applications, in this work, short-chain branches of anhydride, amine, and various acrylate monomers with varying molecular weights were grafted onto PP using reactive extrusion. It was envisioned that such graft co-polymers can enhance the performance of PP making it a viable material such as water heating applications. The main interest herewith is to evaluate the occurrence of the grafting reaction and its effect on the thermal properties of the resulting graft co-polymers. Fourier Transform Infrared (FTIR), Differential Scanning Calorimeter (DSC), Polarized Optical Microscopy (POM), Thermogravimetric Analysis (TGA), gel content, and rheology tests were conducted to evaluate the effect of grafting on the performance of PP. DSC results showed a novel increase in crystallinity and crystallization temperature indicating a nucleating effect by the grafted chains. This is correlated with TGA and rheology results, where an increase in the temperature of maximum degradation and a reduction in the viscosity proved to be converging confirmations of grafting. The results clearly indicated successful grafting of PP which resulted in improved thermal stability that is essential for use in energy applications.