针状硅灰石表面处理及其聚丙烯复合材料的研究

发布时间：2018-03-15 04:05

本文选题：硅灰石　切入点：聚丙烯(PP)　出处：《天津科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：聚丙烯(PP)是一种综合性能优良、应用广泛的通用塑料,但由于其存在机械强度低、成型收缩率大、冲击强度小等缺点,限制了PP在各个领域的拓宽应用,为了提高其强度、模量,改善冲击性能,需对PP进行增强处理。本课题根据硅灰石独特的针状特征,选用四种不同的表面处理方法(如：1.偶联剂处理；2.纤维素处理；3.SiO2包覆处理；4.SiO2/偶联剂以及SiO2/NCC协同处理)对硅灰石进行表面处理,并将处理后硅灰石填充到PP中,熔融共混挤出,制备相应的PP/硅灰石复合材料。选用红外光谱(FTIR)、扫描电镜(SEM)等对处理效果进行表征；借助电子拉力机考察复合材料的力学性能；运用差示扫描量热仪(DSC)、偏光显微镜(POM)等测试手段研究了材料的结晶性能；通过毛细管流变仪分析了体系的流变行为；采用热失重分析仪(TGA)测定材料热稳定性；此外,还利用SEM观察了复合材料的断面形貌,探讨了不同表面处理方法对硅灰石的处理效果,以及硅灰石不同用量对复合体系结构和性能的影响。结果表明：(1) FTIR显示四种偶联剂(KH550、KH570、NDZ-201、DL-411-A)与硅灰石有化学作用,活化指数表明偶联剂KH570和DL-411-A对硅灰石的处理效果较佳。KH570用量为2.0wt%、DL-411-A用量为1.5wt%时,PP/硅灰石体系的拉伸强度、弯曲强度均达到最大值,且体系的熔体流动性得到改善,综合性能较好,同时提高了硅灰石在PP基体中的分散及其与PP基体的界面相容性。(2)MCC、NCC的引入使硅灰石颗粒表面羟基增多,比表面积增大；在一定程度上能够提高复合体系的刚性和硬度,处理硅灰石与PP基体的界面结合性较强,改善冲击韧性；体系熔体粘度随剪切速率增大而减小,仍为假塑性流体,其热稳定性提高。(3)经SiO2包覆处理的硅灰石颗粒表面粗糙,棱角被钝化,改善了其表面性能；且硅灰石填充复合材料的球晶尺寸减小,晶核密度提高,复合体系熔融峰左侧出现了重结晶峰,SiO2粒子起到了异相成核的作用,同时能够提高材料韧性和耐热性能,延缓PP复合材料的热分解,改善PP基体的热稳定性。(4)经协同处理后硅灰石表面羟基、表面粗糙程度均较单一处理增加明显,SiO2/KH570和SiO2/NCC(NCC用量为0.8wt%)两组处理效果最佳；PP/硅灰石复合材料拉伸、弯曲和冲击性能大幅度增加,处理后的硅灰石起到了很好的增强增韧效果,且熔体流动性好,综合性能最优。同时其结晶过程中球晶细化,晶核数增加,二者界面结合强,相容性好,并能够显著地延缓PP复合材料的热分解,提高其热稳定性。(5)随着硅灰石用量的增加,PP/硅灰石复合体系的刚性和韧性下降明显,硅灰石在PP基体中的分散性变差,对体系的加工流动性影响不大,当硅灰石用量为20wt%时,综合性能最佳。
[Abstract]:Polypropylene (PP) is a kind of general plastics with good comprehensive properties and wide application. However, because of its low mechanical strength, large shrinkage rate and low impact strength, it limits the application of PP in various fields, in order to improve its strength. In order to improve the impact property, the PP should be reinforced. According to the unique needle-like characteristics of wollastonite, Four different surface treatment methods (e.g.: 1. Coupling agent treatment 2. Cellulose treatment 3. Sio 2 / coupling agent and SiO2/NCC synergistic treatment) were used to treat wollastonite. The treated wollastonite was filled into PP and extruded by melt blending. The corresponding PP/ wollastonite composites were prepared. The treatment effect was characterized by FTIR and SEM, and the mechanical properties of the composites were investigated by means of electronic drawing machine. The crystallization properties of the materials were studied by means of differential scanning calorimeter (DSC) and polarizing microscope (POM), the rheological behavior of the system was analyzed by capillary rheometer, the thermogravimetric analyzer (TGA) was used to determine the thermal stability of the materials. The cross section morphology of the composite was observed by SEM, and the effect of different surface treatment methods on wollastonite was discussed. And the effect of wollastonite content on the structure and properties of the composite system. The results show that FTIR shows that four coupling agents, KH550, KH570, NDZ-201Z, DL-411-A) and wollastonite have chemical interaction with wollastonite. The activation index indicated that the treatment effect of KH570 and DL-411-A on wollastonite was better. When the dosage of DL-411-A was 1.5wt%, the tensile strength and flexural strength of PP / wollastonite system reached the maximum value, and the melt fluidity of the system was improved, and the comprehensive properties of the system was better. At the same time, the dispersion of wollastonite in PP matrix and the interfacial compatibility between wollastonite and PP matrix were improved. The introduction of MCCNCC increased the surface hydroxyl and specific surface area of wollastonite particles, and to a certain extent, the rigidity and hardness of the composite system were improved. The interfacial bonding between the treated wollastonite and PP matrix is stronger, and the impact toughness is improved. The melt viscosity decreases with the increase of shear rate and is still a pseudoplastic fluid. The thermal stability of the treated wollastonite particles is increased. 3) the surface of wollastonite particles coated by SiO2 is rough. The angle was passivated to improve the surface properties of the composite, and the spherulite size of wollastonite filled composites decreased, the density of crystal nucleus increased, and the recrystallization peak appeared on the left side of the melting peak of the composite system, and the Sio 2 particles played the role of heterogeneous nucleation. At the same time, it can improve the toughness and heat resistance of the composites, delay the thermal decomposition of PP composites, improve the thermal stability of PP matrix, and improve the hydroxyl groups on the surface of wollastonite after co-treatment. Compared with the single treatment, the surface roughness of the two groups was obviously increased, and the content of Sio _ 2 / KH _ 570 and SiO2/NCC(NCC was 0.8 wt. respectively) the two groups had the best treatment effect, such as tensile, flexural and impact properties, and the treated wollastonite had a very good reinforcing and toughening effect. At the same time, the spherulites were refined, the number of nuclei increased, the interfacial bonding was strong, the compatibility was good, and the thermal decomposition of PP composites could be significantly delayed. With the increase of wollastonite content, the rigidity and toughness of PP / wollastonite composite system decreased obviously, and the dispersity of wollastonite in PP matrix became worse, which had little effect on the processing fluidity of the system. Comprehensive performance is the best.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ325.14;TB33

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