Influence of soy protein isolate on the thermal stability of poly(vinyl chloride) in the presence or absence of calcium and zinc stearates

摘要

The influence of soy protein isolate (SPI) and its mixture with calcium stearate (CaSt_2), and zinc stearate (ZnSt_2) with various ratios on the processing thermal stability of poly (vinyl chloride) (PVC) was investigated by measuring dehydrochlorination rate of PVC (DHC), visual color comparison, and ther-mogravimetric analysis (TGA). The results suggested that SPI acted as a long-term thermal stabilizer like CaSt_2 to absorb HC1 released from PVC, which is due to the primary amine (-NH_2) and polyols containing hydroxyl groups in SPI. Moreover, SPI improved the stabilization effect of the traditional CaSt_2/ZnSt_2 stabilizer, and the combination of SPI and CaSt_2/ZnSt_2 at certain ratios exhibited desirable stabilization efficiency in prolonging the discoloration time.