共查询到20条相似文献,搜索用时 171 毫秒
1.
2.
采用两步法在Spheripol聚丙烯中试装置进行高流动高刚抗冲共聚聚丙烯中试开发,获得三种刚韧平衡的中试产品。对产品进行力学性能、乙烯含量、橡胶相含量、DSC测试,采用偏光显微镜(POM)、扫描电子显微镜(SEM)对结晶及脆断面形貌进行观察。结果表明:提高产品中乙烯含量、降低气相反应器中气相比和氢气/乙烯比、提高橡胶相的分子量、细化橡胶相尺寸、改善橡胶相的分散性,均有利于提高产品的冲击强度。降低橡胶相含量、细化球晶尺寸、提高产品结晶度,尤其是均聚部分的结晶度有利于提高产品刚性。降低中试气相比,将产品的乙烯含量控制在4.5%左右,橡胶相含量为9.5%左右,橡胶相尺寸为0.5μm左右,可获得刚韧平衡的高流动高刚抗冲共聚聚丙烯产品。 相似文献
3.
考察了两种不同结构外给电子体甲基环己基二甲氧基硅烷(Donor-A),二环戊基二甲氧基硅烷(Donor-B)对制备的均聚聚丙烯及共聚聚丙烯熔体流动速率和力学性能的影响。采用溶剂分级法、黏度参数法测定了共聚聚丙烯中橡胶相含量、橡胶相及聚丙烯基体的黏均分子量,通过扫描电子显微镜观察共聚聚丙烯中的橡胶相分布及尺寸。结果表明:与Donor-A相比,Donor-B的氢调敏感性较好,用其制备试样的熔体流动速率是Donor-A的1.8倍左右;而以Donor-A为外给电子体制备的试样刚韧平衡性较好,所制共聚聚丙烯的橡胶相黏均分子量较高,且橡胶相分布均匀性较好。 相似文献
4.
5.
采用核磁共振碳谱、红外光谱、凝胶渗透色谱、差示扫描量热法等研究了透明抗冲共聚聚丙烯、普通无规共聚透明聚丙烯、抗冲共聚聚丙烯的结构与性能.结果表明:透明抗冲共聚聚丙烯的乙烯含量介于普通无规共聚透明聚丙烯和抗冲共聚聚丙烯之间,橡胶相含量高于普通无规共聚透明聚丙烯,橡胶相的重均分子量较小,粒径小于0.4μm,分散均一,有利于... 相似文献
6.
7.
在Horizone工艺装置上成功开发了中熔体流动速率(MFR)高橡胶含量抗冲共聚聚丙烯K7116,并表征了其结构,分析了其性能,讨论了不同因素对K7716力学性能的影响。结果表明:K7116的MFR为16 g/10 min,弯曲模量达1 270 MPa,冲击强度为12 kJ/m2;乙丙橡胶含量增加,使K7116的刚性降低,冲击强度增加;橡胶含量、乙丙橡胶部分与均聚聚丙烯部分的相对分子质量比,以及助剂选择对K7116的结晶性能和力学性能均有较大影响。 相似文献
8.
9.
10.
11.
Hong-Sheng Tan Yuan-Zhang Yu Li-Ping Li Xue-Jing Liu Zhe-Xing Tan Yan-Yan Gong 《Polymer-Plastics Technology and Engineering》2015,54(13):1343-1348
Mechanical properties and fracture morphology for long glass fiber-reinforced-polyolefin composites and their blends were investigated. The properties like tensile, flexural, and impact strength of the composites at low temperature increased considerably and elongation at break reduced visibly with increase of glass fiber contents. Impact strength at room temperature was an exception, and impact strength of the composites was higher than that of impact polypropylene copolymer. The results are caused by interaction of rubber phase and amorphous parts in impact polypropylene copolymer. Extraction or fracture for glass fiber in the composites consumed more impact energy, which means they have higher impact strength. 相似文献
12.
为解决聚丙烯材料抗冲击强度低的问题,同时利用国内大量廉价的1-丁烯资源,采用单体组成切换法在反应器内进行丙烯本体均聚和丙烯/丁烯本体共聚,原位制备聚丙烯合金。该合金主要由丙丁无规共聚物、长丙烯链段的丙丁嵌段共聚物和高等规度的聚丙烯组成。共聚物作为橡胶相分散在聚丙烯基体中,形成海岛结构,充当应力集中点,起到诱发及终止银纹、吸收能量的作用。长丙烯链段的嵌段共聚物增加了橡胶相与基体的相容性,使合金材料具有优异的刚性和韧性平衡,材料的抗冲击强度最高达48.91 kJ/m2。本文探究了聚合工艺对合金组成结构的影响,并揭示了合金组成结构和相形态、力学性能的关系。 相似文献
13.
14.
15.
用注塑成型方法制备了抗冲嵌段共聚聚丙(烯PP-B)试样,研究了工艺条件的改变对PP-B力学性能的影响。结果表明:注射速率和模具温度与PP-B弯曲强度、弯曲模量成正相关,而与冲击强度、拉伸强度的关系较为复杂;模具温度的升高有利于结晶度的提高,PP-B刚性上升,韧性下降;注射速率改变引起的剪切、拉伸流动使熔体发生取向流动,从而使沿取向方向上的强度升高,垂直取向方向上的强度降低;保压压力对PP-B性能的影响主要是通过熔体非晶部分在保压阶段的分子定向作用来实现的,随着保压时间的延长,PP-B塑件密度提高缺,陷减少拉,伸强度弯、曲模量呈增大趋势。 相似文献
16.
This article describes the impact and dynamic mechanical properties of rubber‐modified binary blends of polypropylene (PP). Two conventional elastomers [viz. ethylene vinyl acetate copolymer (EVA) and ethylene propylene diene terpolymer (EPDM)] were used as an impact modifier for PP. It is clearly indicated by the results that EPDM is better than EVA as an impact modifier of PP. Analysis of data of dynamic mechanical properties and impact properties at various compositions of the blends revealed a direct correlation between impact properties and dynamic mechanical loss tangent. The energy dissipation due to viscoelastic relaxation is therefore suggested as a mechanism of impact toughening of PP, in addition to the other commonly known mechanisms of toughening (viz. shear yielding and crazing induced by deformation of rubber‐phase domains). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 962–971, 2000 相似文献
17.
18.
Polymer blend technology has been widely used for the past several years for the modification or enhancement of mechanical properties of polymers to obtain an overall balance of properties over those of the constituents. Despite its interesting mechanical and thermal properties, the impact strength of polypropylene leaves wide scope for improvement. A series of blends of ethylene vinyl acetate (EVA) copolymer with an impact grade of isotactic polypropylene (i‐PP) were prepared by single screw extrusion at 0–0.32 volume fraction of the dispersed phase. The mechanical properties such as tensile behavior, elongation‐at‐break, and impact strength of these blends systems as well as crystallinity were evaluated. Crystallinity data have been used in greater depth to support the mechanical properties. Differential scanning calorimetry studies conducted to study the modification in crystallinity of the crystalline component, i‐PP, of the blend revealed that the rubber component of the blend enhanced the crystallinity of i‐PP phase by providing sites for nucleation. Tensile modulus and strength decreased while the impact strength and breaking elongation enhanced with blending elastomer concentration. The improved properties of these PP/EVA blends are encouraging for carrying out further work on this system (composites) and suggest potential high impact strength applications for PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
19.