Preparation And Performance Of TPU-Based Polymer Composites

Thermoplastic polyurethane elastic(TPU)has great potential application in the field of polymer materials because of its high mechanical strength,excellent processing property and excellent comprehensive properties.However,TPU has poor tactile and skin-friendly properties,polyester TPU is not resistant to hydrolysis,and polyether TPU has poor oxidation resistance,which greatly limits its application in biomedical materials and materials directly in contact with the human body,such as smart bracelets,mobile phone coats and other fields.Blending TPU with other types of polymer materials is a common method to improve the performance of TPU.Polyisobutylene(PIB)and silicone rubber(SIR)are polymer materials with excellent biocompatibility.In this paper,TPU was blended with high molecular weight PIB,BIMS Ionomer bromide p-methylstyrene isobutylene copolymer and SIR respectively to prepare three kinds of TPU-based polymer blends.Through universal tensile testing machine,scanning electron microscope(SEM)combined with energy dispersive spectrometer(EDS)and solvent extraction,The effects of blending ratio on the mechanical properties and microstructure of blends were studied.The thermal properties of the blend were studied by differential scanning calorimetry(DSC),thermogravimetric analysis(TGA)and dynamic mechanical thermal analysis(DMA).The antioxidant/hydrolytic properties of the blend were investigated by immersion experiments with nitric acid(HNO₃).The rheological properties and processability of the blends were studied by rubber processing analyzer(RPA).The results show that:1.PIB/TPU blend with high mechanical properties and excellent oxidation/hydrolysis resistance was obtained by physical blending method under the compatibilization of polypropylene grafted maleic anhydride(PP-g-MAH).Because the polarity of PIB and TPU is significantly different,the compatilizer PP-g-MAH must be introduced to improve the interface characteristics.When the ratio of PIB/TPU is 1/9?3/7,TPU is the matrix phase and PIB is the dispersed phase.When the PIB/TPU blending ratio is 5/5,the blends are double-continuous phase distribution.When the ratio of PIB/TPU is 7/3?8/2,PIB changes into matrix phase and TPU is dispersed phase.Compared with high molecular weight PIB,PIB/TPU(7/3)blends showed good mechanical properties and better processing properties,and the tensile strength reached 7 MPa.Compared with TPU,it exhibits better thermal stability and excellent oxidation/hydrolysis resistance.Through slow cooling and heat treatment,PIB can be promoted to migrate to the surface of the blend,which further increases the antioxidant/hydrolytic properties of the blend.2.The BIMS ionomer can be formed through nucleophilic substitution reaction of triphenyl phosphorus P(Ph)₃and brominated p-methylstyrene isobutylene copolymer(BIMS)at high temperature.The optimal reaction conditions are P(Ph)₃/benzyl bromide molar ratio of 2/1,reaction temperature of 120°C,reaction time of10 min.Under the action of compatibilizing agent PP-g-MAH,physical blending of BIMS Ionomer and TPU was carried out.Compared with high molecular weight PIB/TPU blend,mechanical properties of the material were further improved,creep resistance of the blend was significantly improved,and stress relaxation phenomenon was reduced.Compared with high molecular weight PIB/TPU,the creep resistance of BIMS Ionomer/TPU blends is increased by 61%,the stress relaxation is reduced by 15.7%,and the tensile strength is increased to 9.1 MPa when the blending ratio is all 7/3.The mechanical properties,creep resistance and stress relaxation of the blends were characterized by universal tensile testing machine.BIMS Ionomer/TPU also shows better processing performance.3.SIR/TPU blends were prepared by simple physical blending method and dynamic curing method,and the effects of blending ratio,SIR curing system and dosage of curing agent on the properties of the blends were studied.The structure of the polymer was determined by infrared spectroscopy(FTIR),and the mechanical properties,tensile permanent deformation and stress relaxation of the material were characterized by a universal tensile testing machine.The microstructure of the material was studied by scanning electron microscopy(SEM).Through the above characterization methods,the effects of simple physical blending and dynamic vulcanization on the structure,mechanical properties,surface morphology and long-term performance of the materials were compared in detail,which provided a reference for the preparation of materials directly in contact with the human body.