超高分子量聚乙烯凝胶的流变行为

Rheological Behaviour of Ultra High Molecular Weight Polyethylene Gel

采用旋转流变仪研究了超高分子量聚乙烯(UHMWPE)凝胶的流变行为。通过动态应变扫描测定了UHMWPE凝胶的线性黏弹区;通过动态温度扫描、动态频率扫描和稳态速率扫描研究了温度、浓度、剪切速率对凝胶流变行为的影响。结果表明,浓度为2%~22%的UHMWPE凝胶的线性黏弹区对应的应变下限为2%,上限为40%,且温度对凝胶线性黏弹区的影响较大;浓度为6%的UHMWPE凝胶,在180℃时,弹性模量最大,凝胶内部的黏结性最强;UHMWPE凝胶熔体的黏度随扫描频率、剪切速率的升高而降低,呈现明显的剪切变稀行为,属于假塑性流体;剪切速率较高时,UHMWPE凝胶的黏度对温度的变化更敏感。

The rheological behaviour of ultra high molecular weight polyethylene(UHMWPE)gel was studied by using a rotary rheometer.The linear viscoelastic range of the UHMWPE gel was determined by dynamic strain scanning.The effects of temperature,concentration and shear rate on the rheological behaviour of gels were investigated by dynamic temperature scanning,dynamic frequency scanning and steady-state rate scanning.Results showed that the linear viscoelastic region of UHMWPE gel with a concentration of 2%~22%corresponded to a lower strain limit of 2%and an upper limit of 40%,and temperature had a great influence on the linear viscoelastic region of gels.UHMWPE gel with a concentration of 6%had the highest elastic modulus and the strongest adhesion at 180℃.The viscosity of UHMWPE gel melt decreased with the increase of scanning frequency and shear rate.It was exhibited obvious shear-thinning behaviour and belonged to pseudoplastic fluid.The viscosity of the gel was more sensitive to the variation of temperature at higher shear rates.