硅酮粉改性超高分子量聚乙烯及其熔体纺丝加工性能

Silicone powder modified ultra-high molecular weight polyethylene and its melt-spinning processability

针对超高分子量聚乙烯(PE-UHMW)熔体加工性能差的问题,应用硅酮粉,采用熔融共混方法对PE-UHMW进行改性,以提高其熔体加工时的流动性。通过扫描电子显微镜与能量色散谱(EDS)表征了硅酮粉在PE-UHMW中的分布,并采用熔体速率测试、旋转流变测试,分析了硅酮粉含量对PE-UHMW熔体流动速率与流变性能的影响。对改性后的PE-UHMW采用熔体纺丝法制备了PE-UHMW单丝,并进行了拉伸强度测试。实验结果表明,随着硅酮粉的增加,其分散性逐渐变差,PE-UHMW熔体流动速率随硅酮粉含量先增加后降低,当硅酮粉质量分数达到4%,其熔体流动速率最高,复数黏度与储能模量最低,5%质量分数的硅酮粉在PE-UHMW基体中团聚较明显,改性后的PE-UHMW熔体流动性降低。熔体纺丝实验结果表明改性后的PE-UHMW可以通过普通单螺杆挤出机熔融挤出初生丝,经超倍热拉伸可以制备高强度单丝。当拉伸倍率为36时,质量分数3%的硅酮粉改性PE-UHMW单丝拉伸强度最高,可达1565MPa。因此综合考虑加工性能与单丝强度,采用质量分数3%的硅酮粉改性PE-UHMW较合适。

To improve the fluidity of ultra-high molecular weight polyethylene(PE-UHMW)during melt processing,silicone powder was applied and a melt blending method was adopted.The distribution of silicone powder in PE-UHMW was characterized by scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS),and the influence of silicone powder content on the melt flow rate(MFR)and rheological properties of PE-UHMW was analyzed using melt rate testing and rotational rheological testing.Modified PE-UHMW monofilaments were prepared by the melt spinning method,and the tensile strengths were tested.The SEM and EDS results showed that with the increase of silicone powder,its dispersibility gradually deteriorates.The flow rate of PE-UHMW melt first increases and then decreases with the increase of silicone powder content.When the mass fraction of silicone powder reaches 4%,its MFR is the highest,and its complex viscosity and storage modulus are the lowest.The aggregation of 5%mass fraction silicone powder in the PE-UHMW matrix is more obvious,and the MFR of modified PE-UHMW melt decreases.The results of melt spinning experiments indicate that the modified PE-UHMW can be extruded into as-spun filament using a convention‐al single screw extruder,and high-strength monofilaments can be prepared by hot drawing.When the draw ratio is 36,the highest tensile strength of PE-UHMW monofilament modified with 3 wt% silicone powder can reach 1565 MPa.Therefore,considering both processing performance and strength,it is more appropriate to use 3 wt% silicone powder to modify PE-UHMW.