Thermal decomposition kinetics of in situ reinforcing composite based on polypropylene and liquid crystalline polymer

A thermotropic liquid crystalline polymer (TLCP), a copolyester with a 80/20 molar ratio of p-hydroxy benzoic acid (HBA) and poly(ethylene terephthalate (PET), known as Rodrun LC5000, was melt blended with polypropylene (PP) using a twin-screw extruder. The thermal degradation of the blends containing various TLCP contents was investigated using thermogravimetry (TG). In nitrogen and in air, the TG profiles of PP revealed a single weight-loss step, whereas TLCP showed two and three major weight-loss steps in nitrogen and in air, respectively. In air, more complex TG curves were observed for the blends with TLCP loading. Simultaneous DSC thermograms revealed that the degradation processes for all neat polymers and the blends were endothermic in nitrogen and exothermic in air. The kinetic parameters (Ea, ln A, and n) calculated using isoconversional method indicated that the thermal stability of PP was significantly improved by in situ reinforcing with TLCP. Addition of SEBS-g-MA compatibilizer slightly enhanced the thermal resistance of blend.