Static And Dynamic Mechanical Properties And Microstructure Analysis Of Polyvinyl Chloride / Thermoplastic Polyurethane Blends

Polyvinyl chloride（PVC）elastomers are distinctly nonlinear,anisotropic and viscoelastic,and are often used in fields such as soft tissue testing of engineering crash test dummies and the development of safety protection devices.Thermoplastic polyurethane（TPU）is an（AB）n-type multi-block copolymer that combines the high hardness of plastic and the high elasticity of rubber at room temperature.To improve the processability,notch impact resistance and thermal stability of PVC,TPU can be introduced to modify PVC in blends.During testing,such materials are often subjected to impact loading,and the stress-strain behavior of the loading process strongly depends on the strain rate.By adjusting the relative content of the blending system（PVC/TPU）,the static and dynamic mechanical properties of the material can be changed to meet the requirements of different levels of engineering crash tests.In this paper,polyvinyl chloride（PVC）was selected as the base material and thermoplastic polyurethane elastomer（TPU）was introduced as the blending material.PVC/TPU alloy materials with different blending ratios（100/0,90/10,70/30,50/50,30/70,10/90）were obtained by two molding means:molding and twin-screw extrusion,and uniaxial tensile and hardness tests were conducted on them.The elongation at break and Shore hardness were used as guidelines to preferably select the molding method.For quasi-static mechanical properties,uniaxial compression and tensile tests were conducted on PVC/TPU alloy specimens at low strain rates(0.001,0.01,0.1 s^-1)using a universal material testing machine to reveal their nonlinear hyperelastic mechanical properties.For the dynamic mechanical properties,compression and tension experiments were conducted on PVC/TPU alloy specimens at wide strain rates(100～5800 s^-1)using a split Hopkinson pressure bar（SHPB）and a high-speed tensile tester,respectively,to reveal their rate-dependent viscoelastic dynamic mechanical properties.The specimens showed significant strain-rate strengthening effects under both quasi-static and dynamic loading.The functional groups,crystallinity and microscopic morphology of the blends were characterized by Fourier transform infrared spectroscopy（FT-IR）,X-ray diffraction（XRD）and scanning electron microscopy（SEM）to explore the effect of blending ratio on the mechanical properties of the systems.The results showed that the PVC/TPU alloy specimens of the molding group had lower Shore hardness,better resilience and better molding properties.The mechanical properties of the system were tested over a wide strain rate range,and it was found that the blending ratio system affected the microscopic morphology and mechanical properties.The complex morphology of double-continuous phase and"sea-island"structure coexisted when the mixing ratio was 50/50.The research results of this paper can provide theoretical support for the characterization of mechanical properties and dynamic failure assessment of soft tissue materials of dummy.Figure[36]table[8]reference[95]...