Effects of calcium sulfate whisker on the mechanical property, morphological structure and thermal degradation of poly (lactic acid) composites

A comprehensive investigation on the fabrication and characterization of poly (lactic acid) (PLA) composites with varied mass fraction of calcium sulfate whisker (CSW) was presented. Before compounding, silanization strategy on CSW was performed by γ-(2, 3-epoxypropoxy) propytrimethoxysilane (GPTMS), and then mechanical performance, morphological structure and thermal behavior of PLA/CSW composites were explored carefully. It was found that silanization on CSW succeeded in forming well-bonded interfaces between organized CSW and PLA. Though the added CSW resulted in a moderate declination on tensile strength (less than 20%), it showed significant positive influences on the elastic modulus, elongation at break and impact toughness. The processes of glass transition and cold-crystallization were lagged at low concentration of CSW but accelerated again with further addition of whisker, as also affected the variation of actual crystallinity. However, the thermal stability was improved remarkably and kinetics analysis of thermal decomposition revealed that reaction order was hardly changed while activation energy was decreased along with increased CSW.