PVC/TPU共混材料静动态力学性能及本构模型研究

Study on static and dynamic mechanical properties and constitutive model of PVC/TPU blends

利用万能材料试验机和高速拉伸试验机对2种成型方式和6种共混比的聚氯乙烯/热塑性聚氨酯(PVC/TPU)共混材料开展静动态拉伸力学性能测试,并基于断裂伸长率和邵氏硬度进行成型方式和共混比优选。进一步获取了共混材料在较宽应变率范围(0.001~700 s-1)的应力⁃应变数据,并进行了拉伸断面的微观表征。结果表明,模压成型材料断裂伸长率更高,共混比为90/10时材料具有最高的断裂伸长率,邵氏硬度符合试验假人软组织材料的硬度范围(邵尔40~70 A)。共混比为90/10(PVC/TPU)材料在静动态载荷下均具有显著的应变率效应。选取朱⁃王⁃唐(ZWT)方程和Sherwood⁃Frost方程构建了材料的本构模型,对比发现Sherwood⁃Frost方程拟合效果更好。形貌分析发现,静动态加载下,材料均为典型的脆性断裂,未出现明显的相分离现象。随着应变率的增加,断面逐渐变粗糙,并产生空穴及微小裂纹。

In this study,both universal material testing and high⁃speed tensile testing machines were used to measure the static and dynamic tensile mechanical properties of the poly(vinyl chloride)(PVC)/thermoplastic polyurethane(TPU)blends by using two molding methods and six blending ratios.The molding methods and blending ratios were optimized according to the fracture elongation and Shore hardness of the blends.The stress⁃strain data were obtained in a wide strain⁃rate range of 0.001~700 s-1,and microscopic characterization was carried out up on the cross⁃section of the ten⁃sile samples.The results indicated that the molded material obtained higher fracture elongation,and it achieved maxi⁃mum fracture elongation at a PVC/TPU mass ratio of 90/10.The Shore hardness meets the hardness range of the soft tissue material of the test dummy(Shore 40~70 A).The PVC/TPU(90/10)blends exhibited a significant strain⁃rate effect under both static and dynamic loads.The Zhu⁃Wang⁃Tang′s and Sherwood Frost′s equations were employed to construct a constitutive model for the blends,and a comparative investigation indicated that the Sherwood Frost′s equa⁃tion had better fitting effect.The topography analysis indicated that under static and dynamic loads,the blends exhibited a typical brittle fracture without significant phase separation.As the strain rate increased,the cross⁃section became rough gradually and produced voids and small cracks.