Research Of Interaction Relationship Between Thermalplastic Polyurethane And Carbon Dioxide And Compression Molding Foaming Of Them Using ScCO₂

Thermoplastic polyurethane?TPU?is one type of special elastomer material,with high strength as engineering plastics and high elasticity as rubber.It is widely used in industry,life and medical treatment due to its outstanding performance.The application fields are broadened by microcellular foaming of TPU.Various polyurethanes could be obtained by adjusting the types and ratio of soft segment and hard segment.The significant guiding significance on foaming process will be got by studing interaction relationship between TPU and CO₂.This paper studied the interaction relationship between CO₂ and thermoplastic polyurethane?TPU?by using FTIR in high pressure.The interaction relationship was compared between CO₂ and polyether TPU and polyester TPU with different soft segment,and between CO₂ and polyether TPU with different soft segment and hard segment ratio.The induced crystallization of TPU was studied by CO₂ annealing and the enhancement of tensile strength was also studied.The TPU compression molding foaming by scCO₂ was researched.Results indicated that Lewis acid-base interaction between CO₂ and TPU polar groups were occurred and increased with CO₂ pressure increasing.The interaction between CO₂ and polyether TPU was higher than that with polyester TPU.The higher hard segment ratio in polyether TPU,the stror???r interaction with CO₂ was.The hydrogen bond degree of TPU was decreased by the introduction of CO₂.The crystallization degree of TPU was increased due to indued crystallizing by CO₂ annealing;meanwhile,the tensile strength was enhanced due to the crystallization degree increasing.The tensile strength could be increased by 34.1%with slight foaming at low temperature.The results of compression molding foaming of TPU indicated that the higher hard segment ratio,the better foaming performance will be got,with smaller cell diameter,higher cell density,better mechanical properties and stronger styling ability on cell structure after foaming.