超高分子量聚乙烯与高密度聚乙烯共混板材制备工艺研究

Study on Preparation Process of Ultra High Molecular Weight Polyethylene and High-density Polyethylene Blend Plate

采用两种工艺制备超高分子量聚乙烯与高密度聚乙烯共混板材,粉料板材是由混合粉料直接在单螺杆挤出机挤出制得,粒料板材是混合粉料在双螺杆挤出机共混造粒后由单螺杆挤出机挤出制得。采用微型显微镜、扫描电镜、万能材料试验机等研究制备工艺对两种板材的共混状态、弯曲性能和拉伸性能等的影响。研究发现,在板材成型过程中,粒料板材的扭矩比粉料板材的小,说明采用粒料更容易成型板材;用微型显微镜观察发现,粒料板材表面较光滑平整,凸点较少;粉料板材表面粗糙,凸点较多,塑化效果较差,双螺杆挤出机的强烈剪切混合作用有利于改善塑化效果,提高板材表面质量;扫描电镜观察发现超高分子量聚乙烯高度缠结和较高的黏度,使共混材料中超高分子量聚乙烯以分散相的形式分散在高密度聚乙烯连续相中,与粉料板材相比,粒料板材中超高分子量聚乙烯相畴比较小,分布比较均匀,界面层比较模糊,说明粒料板材中超高分子量聚乙烯与高密度聚乙烯相容性较好;分析比较粉料板材和粒料板材的力学性能,粒料板材的弯曲模量和弯曲强度较高,拉伸强度相近,断裂伸长率较高。

Two kinds of processes were used to prepare ultra high molecular weight polyethylene and high-density polyethylene blend plate.The powder plate was made by directly extruding mixed powder in a single-screw extruder,and the granular plate was made by extruding mixed powder in a single-screw extruder after being blended and granulated in a twin-screw extruder.The effects of preparation technology on the blending state,bending properties and tensile properties of the two kinds of plates were studied by micro-microscope,scanning electron microscope and universal material testing machine.It is found that in the process of plate forming,the torque of granular plate is smaller than that of powder plate,which indicates that it is easier to form plate with granular material.Microscope observation shows that the surface of granular plate is smooth and flat,and there are few bumps.The surface of the powder plate is rough,there are many bumps,and the plasticizing effect is poor.The strong shearing and mixing effect of the twin-screw extruder is beneficial to improve the plasticizing effect and the surface quality of the plate.SEM observation shows that UHMWPE is highly entangled and has high viscosity,which makes UHMWPE dispersed in the continuous phase of HDPE in the form of dispersed phase.Compared with powder plate,the phase domain of UHMWPE in granular plate is smaller,its distribution is more uniform and its interface layer is fuzzy,which indicates that UHMWPE in granular plate has good compatibility with HDPE.Comparing the mechanical properties of powder plate and granular plate,it is found that the flexural modulus and flexural strength of granular plate are higher,the tensile strength is similar,and the elongation at break is higher.