Supercritical CO2-Assisted Foaming of Thermoplastic Polyurethane/Thermoplastic Polyester Elastomer and Its Resilience Properties
To overcome the problems of insufficient resilience,low compressive strength and high shrinkage of foamed materials after foaming of thermoplastic polyurethane(TPU),TPU/TPEE foams were prepared by modifying thermoplastic polyurethane(TPU)with thermoplastic polyester elastomer(TPEE)and using supercritical CO2 as foaming agent.The melting and crystallization behaviour,rheological properties of TPU/TPEE blends and the effects of different TPEE contents on the cyclic compression properties,resilience,permanent deformation in compression and foaming properties of TPU/TPEE foams were investigated.The results of differential scanning calorimetry,falling ball rebound and compressional permanent deformation show that the addition of TPEE can reduce the orderliness of TPU molecular chain arrangement and increase the resilience;the results of rotational rheometry show that the introduction of TPEE could effectively improve the viscoelasticity of the blend melt,making the elasticity dominant and significantly improving the foaming properties;the results of cyclic compression show that the addition of TPEE can further improve the compressive properties of the foams.When the mass fraction of TPEE is added at 7%,the TPU/TPEE foam shows a 7.25%increase in drop ball resilience,2.84%decrease in compressive permanent deformation and 326%increase in compressive strength compared to pure TPU foam.
thermoplastic polyurethanethermoplastic polyester elastomersupercritical CO2foaming material
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