Mechanical properties and thermal characteristics of poly(lactic acid) and paraffin wax blends prepared by conventional melt compounding and sub-critical gas-assisted processing (SGAP)

In this study, poly(lactic acid) (PLA)/paraffin wax (PW) blends containing different amounts of PW were investigated. The blends were prepared by a twin-screw extruder using two different methods: conventional melt compounding extrusion and sub-critical gas-assisted processing (SGAP). Then, the blends and neat PLA were injection molded into ASTM 638 Type V tensile bars for evaluation. To observe the effects of the different melt compounding processes and the effects of paraffin wax added to the blends, the rheological properties, crystallization behavior, and thermal stability of the extruded blends, as well as the phase morphology and tensile properties of the injection molded tensile bars, were characterized. The results showed that the addition of paraffin wax yielded tremendous improvements in elongation compared to neat PLA. In addition, samples made by the sub-critical gas-assisted processing (SGAP) extrusion method exhibited more homogeneous phase morphologies and paraffin wax dispersion, better tensile properties and thermal stability, and more consistent material properties as compared to their conventionally compounded counterparts.