Thermal and Rheological Properties of Poly(lactic acid)/Low-Density Polyethylene Blends and Their Supercritical CO2 Foaming Behavior
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Low-density polyethylene (LDPE) was employed to improve the thermal and rheological properties as well as the supercritical CO2 foaming behavior of poly(lactic acid) (PLA) through melt mixing and batch foaming method, due to its long branched chain structure, moderate crystallization capacity and good foamability. The differential scanning calorimetry and polarized optical microscope results showed that the introduction of LDPE had a slight effect for promoting the crystallization of PLA. An important synergistic effect on the rheological properties of PLA/LDPE blends was found through rotational rheometer. With the content of LDPE, the size of spherical LDPE dispersion phase became bigger gradually, which was observed by scanning electron microscope (SEM). A very interesting cellular morphology evolution from flower-like cellular structure to complex cellular structure and then to mono-porous cell structure was found in the SEM images of the PLA/LDPE blending foams with the foaming temperature at 95 °C. The effect of blending ratio and foaming temperature on the cellular morphology and foaming parameters was investigated.
KeywordsPoly(lactic acid) Low-density polyethylene (LDPE) Foam Cellular morphology Blend
This work was supported by the National Science Foundation of China (51703004 and 51673004), the Natural Science Foundation of Beijing (2164058 and 2162012), Top Young Innovative Talents Program of Beijing Municipal University (CIT&TCD201704041), and Beijing Municipal Commission Education Scientific and Technological Innovation Project (KM201510011005).
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