Development of Polymer/Inorganic Nanocomposites Processing Based on an in situ Non-Aqueous Sol-Gel Technology

含有纳米粒子的聚合物复合材料表现出与微粒子共混物不同甚至更好的性能。相反，高粘度和难以实现无团聚的均匀颗粒分布阻碍了共混物的形成。在本项目的应用中，我们提出了一种基于加工过程中二氧化硅纳米颗粒在聚合物基质中原位形成的制备聚合物纳米复合材料的新路线。非挥发性、疏水性的超支化聚烷氧基硅氧烷被用作二氧化硅前驱体。聚合物前驱体是为聚丙烯的最佳相容性和加工性量身定做的。控制聚乙氧基硅氧烷向SiO_2-x(OH)_2x的转变可以有效地降低聚合物熔体在加工过程中的粘度，使粒子浓度达到10wt-%以上，粒子尺寸小于50 nm。纯聚乙氧基硅氧烷可产生球形二氧化硅颗粒，而层状硅酸盐的原位生成将通过添加镁或铝、钾或铵盐以及使用长烷基改性的聚乙氧基硅氧烷来尝试。本工作开发的非水溶胶凝胶技术将转化为使用同向啮合双螺杆挤出机的连续工艺。得到的纳米复合材料将通过注射成型进行进一步加工。此外，还将通过对成核、刚性和提高冲击强度的重点研究，研究其形态和成分特性以及完整的工艺分析。

Polymer composites containing nanoscale particles have been shown to exhibit properties which differ from and are even superior to those of microparticle blends. In contrast, the formation of blends is hampered by high viscosities and difficulty in achieving a homogeneous particle distribution without agglomeration. In this project application, we propose a new route for preparing polymer nanocomposites based on in situ formation of silica nanosized particles in the polymer matrix during processing. Non-volatile, hydrophobic hyperbranched polyalkoxysiloxanes are employed as silica precursors. The polymeric precursors are tailored for optimum compatibility and processing of polypropylene. Control of the transformation of the polyethoxysiloxane to SiO2-x(OH)2x can efficiently reduce the viscosity of the polymer melt during processing and achieve particle concentrations of more than 10 wt.-% with particle sizes smaller than 50 nm. Whereas pure polyethoxysiloxanes yield spherical silica particles, the in situ creation of layered silicates will be attempted by adding magnesium or aluminium and potassium or ammonium salts, and by using long alkyl-modified polyethoxysiloxanes. The non-aqueous solgel technology developed in this work will be transferred to a continuous process using a corotating intermeshing twin-screw extruder. The resulting nanocomposites will be further processed by injection moulding. Furthermore, the morphology and component properties as well as a complete process analysis will be studied by focussing on nucleation, stiffness and improved impact strength.