Thermoplastic polyurethane (TPU) modifier to develop bimodal cell structure in polypropylene/TPU microcellular foam in presence of supercritical CO2 |
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| Authors: | Jie Wang Jun Li Hui Li Hongfu Zhou |
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| Affiliation: | 1. Applied Chemistry Department, Yuncheng University, Yuncheng, China;2. Beijing Key Laboratory of Quality Evaluation Technology for Hygiene and Safety of Plastics, School of Materials Science and Mechanical Engineering, Beijing Technology and Business University, Beijing, China |
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| Abstract: | Currently, the fabrication of microcell and bimodal cell structures (BCS) in polymer foams by using supercritical fluids has become a hot as well as a challenging research area worldwide. In this work, an environmentally friendly, effective, facile, and CO2-based foaming technique was presented to fabricate microcellular polypropylene (PP) foams with BCS via blending with thermoplastic polyurethane (TPU). The toughness, thermal properties, rheological properties, and foamability of PP were systematically investigated with gradual incorporation of TPU. Representative sea-island structure was observed in the scanning electron microscopy (SEM) images for the fracture surface of various PP/TPU samples. Rheological measurement results demonstrated that the viscoelasticity of various PP/TPU samples was improved remarkably compared with that of pure PP and pure TPU. The impact strength of various PP/TPU samples possessed the highest value as 12.4 kJ/m2 with the TPU content of 15 wt%. After the addition of TPU, an ameliorative cellular morphology was observed in the SEM micrographs of various PP/TPU samples and their volume expansion ratio was enhanced significantly thanks to their improved melt elasticity. Moreover, it is worth noting that BCS appeared in various PP/TPU foams when the TPU content exceeded 5 wt%. |
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| Keywords: | bimodal cell structure microcellular foam polypropylene supercritical CO2 thermoplastic polyurethane |
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