【作者】 袁园；

【导师】 丁雪佳；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2010， 硕士

【摘要】 双峰聚乙烯是指分子量呈双峰分布的聚乙烯,其中的低分子量部分提供了良好的加工性能,高分子量部分提供较好的力学性能,它是继茂金属聚乙烯之后的又一新型材料,由于它特殊的结构使得双峰聚乙烯比普通聚乙烯具有更高的强度、韧性及耐环境应力开裂。由于它是一种新型的材料,人们对它的加工和使用还处在摸索阶段。国内外对它的研究都集中在两个方面：一是开发新型双峰聚乙烯生产用催化剂；二是研究其结构和性能之间的关系。PE100是近几年快速发展起来的双峰聚乙烯,具有更高的应力和抗裂性能,它广泛用于管材,主要特点是耐压等级提高,相同压力下管壁可以更薄,但其耐热性不好,限制了其生产应用。本文应用双螺杆挤出机,采用尼龙6(PA6)改性PE100,熔融挤出制备PE100/PA6共混物,系统研究了加工温度、共混工艺、增容剂种类、不同黏度的PA6对共混物力学性能、耐热性、结晶行为、形态结构及动态流变行为的影响。研究结果表明：加工温度及共混工艺对共混物力学性能影响不大；随增容剂POE-g-MAH或HDPE-g-MAH添加量的增加,PE100/PA6(100/7)共混物的拉伸强度有所提高,然后降低,在含量3%左右时达到最大；冲击强度和断裂伸长率随POE-g-MAH含量的增加而增加,随HDPE-g-MAH含量的增加先增加后降低,在含量为5%左右时达到最大；PE100/PA6 (100/7)共混物的耐热性随POE-g-MAH或HDPE-g-MAH含量的增加先增加后降低,在POE-g-MAH或HDPE-g-MAH含量在3%左右时达到最大；POE-g-MAH或HDPE-g-MAH均使PE100/PA6 (100/7)共混物的复数黏度、储能模量、耗能模量增加,剪切应力均降低；POE-g-MAH或HDPE-g-MAH能使PE100/PA6 (100/7)共混物中PA6分散相的粒径减小,粒径分布变的均匀,相界面趋于模糊。对比相容剂POE-g-MAH或HDPE-g-MAH对共混物力学性能、形态结构的影响,发现HDPE-g-MAH的增容效果更好。采用HDPE-g-MAH做增容剂,发现PE100/PA6共混物的拉伸强度随PA6含量的增加而降低,冲击强度随着PA6含量的增加先增加后降低；广角X射线衍射(XRD)研究表明,PA6阻碍PE100的结晶,使PE100结晶度降低；偏光显微镜(POM)观察表明,PA6限制了PE100的球晶生长,使球晶尺寸减小,晶粒细化；扫描电镜(SEM)观察发现,随着PA6含量的增加,PA6分散变差,粒径变大,均匀性变差。PE100/HDPE-g-MAH/PA6共混物维卡软化点随着低黏PA6含量的增加先增加后降低,含量在15%左右时达到最大,比纯PE100提高了8.1℃。对于高黏PA6, PE100/PA6/HDPE-g-MAH (100/30/15)共混物的维卡软化点达到140.8℃，比纯PE100提高13.2℃。更多还原

【Abstract】 Bimodal polyethylene is a bimodal distribution of molecular weight polyethylene,low molecular weight part of which provides a good processing properties and high molecular weight part to provide good mechanical propert-ies.It is another new material after metallocene polyethylene.Bimodal polyet-hylene has higher strength,toughness and resistance to environmental than or-dinary polyethylene because of its unique structure.PE100 is a kind of bimodal polyethylene which develops fast those years and widely uses in the tubing.Its main feature is higer pressure resistance rank and the pipe wall is thinner under the same pressure.But its thermal stability is not good which limite its application.This paper modified PE100 with PA6,melt extrusion to prepare PE100/ PA6/HDPE-g-MAH(POE-g-MAH) blends,has studied the influence of temper-ature,the blending craft,the compatilizer type and the amount,different viscosi-ty PA6 and the amount systematically on the mechanical properties,the shape structure,thermally stable,the crystal behavior and the dynamic changing beha-vior.The experimental result indicated that:The processing temperature and the blending craft have little influence on the mechanical properties of blends;Tensile strength of PE100/PA6(100/7) blends has increased and then decreased with the increasing of the POE-g-MAH or HDPE-g-MAH content and it reaches the maximum when the content of POE-g-MAH or HDPE-g-MAH is 3%; Impact strength and elongation at break of PE100/PA6(100/7) blends have increased with the increasing of the POE-g-MAH content and have increased and then decreased with increasing of the HDPE-g-MA H,which reaches the highest point when the content of HDPE-g-MAH is 5%; Heat resistance of PE100/PA6(100/7) blends has increased and then decreased with increasing of the POE-g-MAH or HDPE-g-MAH and it reaches the maximum when the content of POE-g-MAH or HDPE-g-MAH is 3%; After joining POE-g-MAH or HDPE-g-MAH,the complex viscosity,the storage modulus,consume energy the module increase,the shear stress reduces; POE-g-MAH or HDPE-g-MAH all make particle size of PA6 in the PE100/PA6 blends smaller,particle size distribution becomes uniform and the interface becomes fuzzy.Comparison of the influence of POE-g-MAH or HDPE-g-MAH on the mechanical and morphology properties of the PE100/ PA6(100/7)blends,found that HDPE-g-MAH compatibilizer is better. With the content of PA6 increasing,tensile strength of PE100/PA6 blends has decreased and impact strength first increases and then decreases when the compatibilizer is HDPE-g-MAH;wide-angle X-ray diffraction(XRD) study shows that PA6 hinders the crystallization of PE100 and causes the crystallinity of PE100 to reduce; polarized light microscopy(PLM) indicate PA6 has the role of nucleating agent which the spherulite size decreases; scanning electron microscopy(SEM) find PA6 dispersed variation,particle size and uniformity variation when the content of PA6 is increasing.With the increasing of low viscosity PA6,Vicat softening point of PE100 /PA6/HDPE-g-MAH blends first increases and then decrease, which reaches the highest point when the content of low viscosity PA6 is 15%.It is higher than pure PE100 with 8.1℃.For high viscosity PA6,Vicat softening point of PE100/PA6/HDPE-g-MAH(100/30/15) blends reaches 140.8℃,higher than pure PE100 increased 13.2℃.更多还原