超高分子量聚乙烯流变性能及挤出性能研究

Study on rheological and extrusion properties of UHMWPE

超高分子量聚乙烯(UHMWPE)分子量高,流变性能差,不利于加工;笔者使用纳米级蒙脱土对其改性;并采用Rosand RH-7流变仪对三种不同分子量的UHMWPE样品进行流变行为对比分析,使用Haake转矩流变仪、平行同向双螺杆挤出机考察蒙脱土添加量和挤出温度对UHMWPE熔体挤出性能的影响。结果表明:三种不同分子量的UHMWPE样品均有剪切变稀现象,为典型的非牛顿流体;随着温度的升高,三种UHMWPE样品的表观黏度均下降、非牛顿指数均提高,相同温度下,非牛顿指数n为:n(UHMWPE-1)>n(UHMWPE-2)>n(UHMWPE-3);随着剪切速率的提高,三种UHMWPE样品的表观黏度均下降、黏流活化能均下降;在相同的剪切速率下,三种UHMWPE的黏流活化能大小为:△E_(η)(UHMWPE-3)>△E_(η)(UHMWPE-2)>△E_(η)(UHMWPE-1);添加蒙脱土,三种UHMWPE在不同的温度下扭矩均下降;蒙脱土添加5.0%时,扭矩下降最明显;蒙脱土添加5.0%时,挤出性能最优。

Ultra high molecular weight polyethylene(UHMWPE)has high molecular weight and poor rheological properties,which is not conducive to processing.Nano montmorillonite was used to modify it.The rheological behaviors of three UHMWPE samples with different molecular weights were compared and analyzed by Rosand rh-7 rheometer,and the effects of montmorillonite addition and extrusion temperature on the extrusion properties of UHMWPE melt were investigated by Haake torque rheometer parallel co rotating twin screw extruder.The results show that the three UHMWPE samples are typical non Newtonian fluids with shear thinning.With the increase of temperature,the apparent viscosity of the three UHMWPE samples decreased and the non-Newtonian index increased.At the same temperature,the non-Newtonian index was n(UHMWPE-1)>n(UHMWPE-2)>n(UHMWPE-3).With the increase of shear rate,the apparent viscosity and viscous flow activation energy of the three UHMWPE samples decreased.At the same shear rate,the activation energies of the three uhmwpes are:△E_(η)(UHMWPE-3)>△E_(η)(UHMWPE-2)>△E_(η)(UHMWPE-1).With the addition of montmorillonite,the torque of the three uhmwpes decreased at different temperatures.When 5.0%montmorillonite was added,the torque decreased most obviously.When 5.0%montmorillonite was added,the extrusion properties of the three uhmwpes were good.