【作者】 谭秀民；

【导师】 许湧深；

【作者基本信息】 天津大学 ， 应用化学， 2007， 博士

【摘要】 聚烯烃类塑料（包括聚丙烯PP,乙丙橡胶EPR等）是用途很广的通用塑料,具有产量大,价格低,耐水,耐化学药品,以及成型工艺简单等优点。但是由于PP是非极性结晶型聚合物,因此难以进行表面处理,涂装,也难以与其他聚合物或填料共混,给开发PP合金材料和复合材料带来了极大的困难。本文首先对聚烯烃的接枝改性以实现聚烯烃的功能化进行了较为详细的研究。以聚丙烯（PP）、乙丙橡胶（EPR）为研究对象,以马来酸酐（MAH）为接枝单体,首次采用预辐射接枝、超声接枝以及微悬浮共辐射接枝方法合成PP、EPR接枝MAH。考察了各种因素,如辐射剂量、超声功率、单体浓度、反应温度、反应时间等对PP、EPR接枝率（G）和接枝效率（GE）的影响,给出了每种接枝体系的最佳接枝条件。结果表明,微悬浮共辐射接枝法得到的产物接枝率最高;用DSC和XRD分析其晶态性能,发现PP接枝MAH后,熔点降低、结晶度和结晶温度有所提高,但接枝前后主链晶型没有发生根本变化。上述几种接枝方法的接枝率可达到6%,与国内外同类接枝产品比较,采用辐射接枝的技术路线已达到先进技术水平。选用硅烷偶联剂以及自制的马来酸酐接枝聚烯烃作为PP/SiO₂复合体系的界面增容剂,采用超声法制备了PP纳米复合材料。研究了不同增容剂、纳米SiO₂含量对复合材料的拉伸强度、断裂伸长率等力学性能;并利用DSC, XRD,IR,SEM等分析手段,讨论了复合材料结构与性能的关系。结果表明,硅烷偶联剂-马来酸酐接枝聚烯烃复合增容剂比单一硅烷偶联剂具有更好的增韧增强效果。对于不同的PP纳米复合材料,纳米SiO₂粒子的填充量都存在一个最佳值,随着填充量增大,出现团聚现象,导致各项力学性能随着掺入量的增加而降低。通过DSC及XRD对复合材料结晶特性的研究表明,纳米SiO₂粒子改性的复合材料的晶形为α晶形,与纯PP相同,熔点并无明显变化;均匀分散在PP中的纳米SiO₂对PP的结晶起到成核剂的作用。通过SEM研究了PP以及PP纳米复合材料的断面形貌,发现纳米SiO₂粒子分散良好,起到了阻止裂纹的扩散,使基体树脂发生了屈服形变的作用,使得复合材料获得良好的增强增韧效果。更多还原

【Abstract】 Polyolefin (including Polypropylene (PP) and Ethylene-propylene rubber (EPR)) is a general purpose plastic and its application fields are very wide. It has many merits, such as the higher yield, lower price, water resistance, chemicals resistance and the simple technological process. In view of no polar and a crystalline polymer the polyolefin is, it is difficult to create superficies, or to brush, or to blend with other polymer and filling matter, so it is difficult to develop the novel polyolefin alloys.First, graftings of polyolefin with maleic anhydride for its functionalization was studied. Maleic anhydride grafting onto polypropylene and ethylene-propylene rubber were prepared by novelty means of pre-irradiation, ultrasoication and co-irradiation. The effects of irradiation dose, ultrasonic intensity, monomer concentration, reaction temperature, and reaction time on the percentage of grafting (G) and grafting efficiency (GE) were investigated. The results show that G is highest by co-irradiation in microsuspention than other means. The crystal degree of PP-g-MAH is higher than PP by DSC and XRD, so did the crystal temperature. But the crystal configuration of main molecule chain is not changed. The percentage of grafting of the products obtained above is 6%. The obtained products by irradiation grafting reaches an advnaced level of the same products of both domestic and foreign countries.In this thesis a kind of silane coupling agents and maleic anhydride (MAH) grafted polyolefin (PO-g-MAH) obtained above were employed as interface compatibilizers for PP/nano-SiO2. PP nanocomposites were prepared by ultrasonic. The composites with different compatibilizers and nano-SiO2 content were characterized by means of mechanical testing, Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), Fourier transformation infra-red spectroscopy (FT-IR), Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), etc. The relation between the structure and property of the composites was discussed in this thesis. The results show that the PP filled by using nano-SiO2 modified with different interface compatibilizers has better mechanical performances than pure PP. The mechanical properties of the PP/nano-SiO2 modified with silane coupling agent and PO-g-MAH are better than that of the PP/nano-SiO2 modified with solo coupling agent. It is also found that there is some optimum dosage of nano-SiO2 in the PP/nano-SiO2. XRD and DSC were used to investigate the surface treatment and the usage of the nano-SiO2 influencing their crystalline characteristic. Results showed that PP/nano-SiO2 has the same crystal type with the pure PP. So the melt point changes a little. Nano-SiO2 acts as the nucleation agent in PP. The SEM results show that nano-SiO2 is dispersed well in PP, which promoted the matrix undergo shear yielding rather than brittle fracture.更多还原