【作者】 吴照勇；

【导师】 李惠林；

【作者基本信息】 四川大学 ， 材料学， 2007， 硕士

【摘要】 本论文采用聚烯烃弹性体（POE）增韧聚丙烯（PP），用偶联剂（单一处理与复合处理）对纳米SiO₂进行表面处理以及在经过预处理的纳米SiO₂表面通过乳液聚合接枝上丙烯酸乙酯制成纳米SiO₂／PEA复合粒子，并加入增容剂PP-g-MA，在超声辐照作用下制备了PP／POE、PP／POE／SiO₂、PP／POE／PP-g-MA／SiO₂共混复合体系，研究了在上述不同条件下制备的聚丙烯复合体系的力学性能、结晶性能、弹性体粒子和纳米SiO₂粒子在复合体系中的分散状况以及超声辐照作用下PP／POE共混体系的挤出流变行为，用FTIR和XPS讨论了纳米SiO₂／PEA复合粒子中丙烯酸乙酯在纳米SiO₂表面的接枝反应。对超声辐照作用下PP／POE共混体系的研究结果表明，PP／POE共混物熔体的表观粘度和口模压力随超声功率的增大而降低。超声辐照能减小分散相POE粒子的尺寸，使分散更均匀，提高与PP的相容性。适宜功率的超声辐照对POE增韧PP能起到协同增韧的效果，而这种效果在脆韧转变前表现更加明显。POE的加入和超声辐照均阻碍了PP的结晶，POE的加入对PPβ晶的生成有一定的诱导作用。对不同表面处理的纳米SiO₂填充体系的研究结果表明，适当的超声功率辐照可以提高复合体系的冲击强度，断裂伸长率。添加增容剂PP-g-MA后，复合体系的冲击强度、屈服强度均得到提高，但断裂伸长率降低。纳米SiO₂能提高PP／POE／SiO₂复合材料的结晶温度，添加增容剂后，结晶温度得到进一步提高。由偶联剂复合处理的纳米SiO₂填充的PP／POE／SiO₂三元体系，其DSC曲线出现β晶峰，随增容剂的加入，β晶峰消失。纳米SiO₂的加入使PP球晶尺寸变小、晶粒细化，超声辐照、增容剂的加入使得球晶尺寸进一步变小、晶粒进一步细化。通过乳液聚合可以成功地将EA接枝到预处理的纳米SiO₂表面上，制成纳米SiO₂／PEA复合粒子，由其填充的PP／POE／SiO₂复合体系，在纳米SiO₂含量4wt％时，冲击强度达到最大值，而此时其DSC曲线上的β晶峰的强度最强。这种处理的纳米SiO₂在PP／POE／SiO₂复合体系中的分散尺寸，分布均匀程度都好于偶联剂处理的。更多还原

【Abstract】 In this paper, a polyolefin elastomer （POE） was selected to toughenpolypropylene （PP）. The surface of nano-SiO₂ was modified with the couplingagent. The nano-SiO₂/PEA hybrids were prepared via emulsion polymerization.With the addition of the compatilizer （PP-g-MA）, the PP/POE blends and thePP/POE/SiO₂ as well as PP/POE/PP-g-MA/SiO₂ composites were prepared duringextrusion under ultrasonic irradiation. The mechanical properties, crystallizationproperties and morphology of PP composites were studied and the rheologicalbehavior of PP/POE blends also was investigated. Through FTIR and XPS, thegrafting reaction of EA onto the surface of nano-SiO₂ for the nano-SiO₂/PEAhybrids was discussed.According to the results of the PP/POE blends under ultrasonic irradiation,the apparent viscosity of the PP/POE blends melt and the die pressure decreasewith increasing the ultrasonic intensity. The ultrasonic irradiation can enhance thecompatibility between PP and POE, reduce the size of POE particles and improvethe dispersion of POE in PP matrix. Appropriate ultrasonic irradiation and POEhave the synthetic effects on toughening PP. And the effects show moreremarkably before the brittle-ductile transition. Both POE and the ultrasonicirradiation control the crystallization behaviors of PP, and the addition of POE caninduce the formation ofβ-crystal. For the PP composites with nano-SiO₂ modified by the different treatments,appropriate ultrasonic irradiation can increase the izod-notched impact strengthand the elongation at break of the composites. The izod-notched impact strengthand the yield strength of the composites are further improved with the addition ofthe compatilizer whereas the elongation at break decreases. Compared with thePP/POE blends, the crystallization temperature of PP/POE/SiO₂ composites isincreased. The addition of the compatilizer further improves the crystallizationtemperature of PP/POE/SiO₂ composites. The melting peak ofβ-crystal occurs inDSC curves for PP/POE/SiO₂ composites with nano-SiO₂ modified with KH-550and NDZ-201. With adding the compatilizer, the melting peak ofβ-crystaldisappears. The spherulite size of PP is reduced and the spherulite is fined withthe addition of nano-SiO₂. The introduction of ultrasonic irradiation or thecompatilizer can strengthen this effect.Ethyl acrylate can be grafted successfully onto the surface of the pretreatednano-SiO₂ via emulsion polymerization and the nano-SiO₂/PEA hybrids preparedare used to modify the PP/POE blends. The izod-notched impact strength and thepeak intensity ofβ-crystal in DSC curves for PP/POE/SiO₂ compsoties reach themaximum value with 4wt% SiO₂. The dispersion of the nano-SiO₂/PEA hybrids inPP/POE/SiO₂ composites is better than that of SiO₂ treated with the couplingagent.更多还原