【作者】 程凤梅；

【导师】 陈大俊；

【作者基本信息】 东华大学 ， 材料科学与工程， 2011， 博士

【摘要】 热塑性聚烯烃和尼龙(PA)都是缺口敏感性聚合物,众所周知,聚丙烯(PP)、聚乙烯(PE)因其良好的加工性能及价格相对低廉而得到了广泛应用,但刚性和韧性的不足限制了它们在工程领域的应用,PA是目前应用最广泛的一类工程塑料,由于吸水率大,稳定性差和缺口敏感,在工程应用中受到一定程度的限制。因此,提高PP、PE和PA的刚性和韧性就成为高分子科学界和工程界的一重要研究课题。本论文主要开展以下四个方面的工作：采用过氧化二异丙苯(DCP)降解PP,研究了三元乙丙橡胶(EPDM)增韧降解PP的结构与性能；刚性粒子玻璃微珠(GB)和纳米二氧化硅(SiO2)增韧PE的性能；ABS增韧PA6的结构与性能；抗冲改性剂乙烯-1-辛烯共聚物(POE)接枝甲基丙烯酸环氧丙酯(GMA)POE-g-GMA的制备及其对PA66的增韧。得到的主要结果有：1.采用DCP对PP进行降解,制备了降解PP/EPDM共混物。通过测试不同温度下共混体系冲击强度,研究了降解PP/EPDM共混体系脆韧转变规律,得到了共混体系在脆韧转变点脆韧转变温度与EPDM含量关系。发现温度和EPDM含量对共混物的韧性和脆韧转变的影响是等效的,增加EPDM含量可以降低体系脆韧转变的温度。得到了共混体系在脆韧转变点临界粒子间距ID。与温度的关系,与弹性体增韧聚合物类似。SEM观察表明分散相在基体中分布均匀。常温下共混物的拉伸强度随着EPDM含量的增加而降低,断裂伸长率在EPDM含量0-12%内增加,超过12%后则减小。DSC、WAXD等研究结果表明,降解PP以均相成核的三维球晶方式生长,EPDM含量影响降解PP的结晶形态,影响晶粒的尺寸分布。2.用GB和纳米Si02增韧PE,通过Izod缺口冲击强度测试、拉伸强度测试和扫描电子显微镜观察,研究了偶联剂处理、基体韧性和刚性粒子用量等因素对刚性粒子增韧PE共混体系微观结构和性能的影响。发现偶联剂可以明显改善GB和纳米Si02在PE基体中的分散。刚性粒子用量有一临界值,HDPE/GB共混体系临界值是25%,纳米Si02体系是3%,可见粒径越小填充量越小。从共混物冲击断面微观形貌可以看出共混物的冲击呈现韧性断裂,出现明显的塑性形变。3.用ABS增韧nylon-6,以马来酸酐接枝聚丙烯和环氧树脂为增容剂,用双螺杆挤出机制备nylon 6/ABS共混物,通过扭矩测试、力学性能测试、微观形态分析和DSC分析,得出结论：增容剂环氧树脂和MAP能够减小分散相ABS与基体nylon 6间的张力,提高nylon 6/ABS共混体系的相容性,从而导致分散相ABS的尺寸减小,显著提高了共混体系的韧性。nylon 6/ABS共混体系拉伸强度和缺口冲击强度均得到提高,而热稳定性基本没变化,达到了增韧增强目的。4.以DCP为引发剂,GMA为活性单体,采用熔融共混法制备抗冲改性剂POE-g-GMA,考察了影响POE-g-GMA接枝率的因素,最终确定出最佳工艺条件为：DCP含量取0.5%,GMA含量在6%,反应温度取170℃,反应时间6-10min。采用最佳工艺制备抗冲改性剂POE-g-GMA,测得其接枝率为4.1%。然后用POE-g-GMA增韧PA66,测试了共混物的力学性能,发现POE-g-GMA能够有效地增韧PA66,POE-g-GMA含量达到30%时,共混物的缺口冲击强度提高到基体PA66的4倍左右。更多还原

【Abstract】 Pyroplasticity Polyolefin and nylon are notch-sensitive polymer. It is generally known that polyethylene and polypropylene are widely used due to their good processing properties and relatively low cost. However, low toughness and rigidity limits their further application in engineering field. Nylon is widely used in engineering applications. But its further application is limited by the notch sensitivity, the lack of stability of dimension and higher absorption of moisture. Thus, improving the toughness and rigidity of polyethylene, polypropylene, and Nylon becomes an important research topic in both polymer science and engineering. In this study, the degraded polypropylene by DCP was toughened by EPDM, polyethylene was toughened by rigid particles glass bead and nano-SiO2, nylon 6 was toughened by ABS, nylon 66 was toughened by POE-g-GMA, and the structure and property of the resulting materials was systemically studied. The following results were obtained.1. When PP was degraded by DCP and degraded PP/EPDM blends was prepared. The toughening change rule of degradation PP/EPDM blends with test impact strength of blends at different temperature. We have got the relation of the brittle-ductile transition temperature and the EPDM content in degraded PP/EPDM blends at brittle-ductile transition spot. The influences on brittle-ductile transition of the degraded PP/EPDM blends by the temperature and the EPDM content are equivalent, and the degraded PP/EPDM blends will be brittle-ductile by increasing temperature or increasing EPDM content, thus, the brittle-ductile transition temperature can be reduced when increasing EPDM content. The correlation between the critical interparticle distance (IDc) and temperature was successfully obtained, in degraded PP/EPDM blends at brittle-ductile transition spot. Similar to the results of thermoplastic/elastomer blends, it was found that the EPDM can be well-dispersed in matrix. At normal temperature the tensile strength of degraded PP/EPDM blends decreases with the increase of EPDM content, The elongation at break decreases with the increase of EPDM content, and it is down to minimum when the EPDM content is 12%, then the elongation at break increases with the increase of EPDM content. DSC and XRD result shows that Degraded PP spherulite growth of three-dimensional way. EPDM has impact on the crystal morphology, grain size distribution of degraded PP.2. Polyethylene was toughened by rigid particles glass bead and nano-SiO2. The affecting factors of PE with rigid particles, such as treatment of coupling agent, matrix toughness, and its content were studied. Its structure and properties were studied by mechanical property testing and electron microscopescanning. It is obvious that the silane coupling agent is beneficial to the GB and nano-SiO2 dispersion in matrix, Rigid particles dosage has a critical point-it is 25 percent to PE/GB blends and 3 percent to PE/nano-SiO2 blends. The critical point of nano-SiO2 blends is smaller than PE/GB blends. From the blends impact cross-section micromor-phologies, we can see blends impact present ductile fracture and apparent plastic deformation.3. Nylon 6/poly(acrylonitrile-butadiene-styrene)(ABS) blends were prepared by a twin-screw extruding machine. Maleic anhydride copolymer and solid epoxy resin were used as compatibilizers for these blends. The effects of compatibilizers were studied by torque test, mechanical property test, morphology testes and DSC analysis. The results show that the additions of epoxy and MA copolymer into nylon 6/ABS blends appeared to enhance the compatibility between nylon 6 and ABS, enhanced the toughness of blends greatly. The tensile strength and notched impact strength of nylon 6/ABS blends are both improved, while the thermostability is not changed. Therefore, the purpose of toughening and reinforcing was reached.4. In DCP initiator, the GMA for active monomers preparated POE-g-GMA, by melt blending process. study on effect factor of POE-g-GMA. In the best technical conditions for:DCP content take 0.5%, GMA content in 6%, reaction temperature 170℃, reaction time took 6-10min, POE-g-GMA can effectively toughening PA66. While POE-g-GMA content is up to 30%, blends notched impact strength increased to 4 times that of matrix PA66.更多还原