Titone Vincenzo, Mistretta Maria Chiara, Botta Luigi, Mantia Francesco Paolo La
Department of Engineering, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy.
INSTM Consortium for Materials Science and Technology, Via Giusti 9, 50125 Florence, Italy.
Polymers (Basel). 2021 Aug 10;13(16):2673. doi: 10.3390/polym13162673.
This work investigates the effects of very small amounts of fumed silica on the morphology and on the rheological and mechanical behaviour of polypropylene nanocomposites and on their photo-oxidation behaviour. Polypropylene nanocomposites were prepared using a twin-screw corotating extruder with 0, 1 and 2 wt/wt% of SiO. Morphological, mechanical, thermomechanical and rheological properties were examined. It was found that the viscosity of the matrix is reduced by the presence of the silica nanoparticles, suggesting a poor adhesion between the two phases and probably some lubricating effect. On the contrary, the mechanical and, in particular, the thermomechanical properties of the matrix are considerably improved by the presence of the silica. In particular, elastic modulus and tensile strength increases remarkably, and this effect becomes more and more remarkable with an increasing temperature. As for the photo-oxidation behaviour, the presence of silica improves the photostability of the polypropylene matrix. This effect has been attributed to both the barrier to the oxygen and to the absorbance of the UV radiation from the silica nanoparticles. Finally, no significant effect of the silica nanoparticles has been put in evidence on the crystallisation behaviour of the polypropylene. As for the effect of the silica content, the difference in the properties of the two nanocomposites is relatively small and all the measured properties depend much less than linearly with its amount. This has been correlated with the reaggregation of the nanoparticles that, having a larger size, decrease the contact area between the matrix and the filler.
本研究考察了极少量气相二氧化硅对聚丙烯纳米复合材料的形态、流变学和力学行为及其光氧化行为的影响。使用双螺杆同向旋转挤出机，以0、1和2 wt/wt%的SiO制备聚丙烯纳米复合材料。对其形态、力学、热机械和流变性能进行了研究。结果发现，二氧化硅纳米颗粒的存在降低了基体的粘度，这表明两相之间的粘附性较差，可能存在一些润滑作用。相反，二氧化硅的存在显著改善了基体的力学性能，特别是热机械性能。特别是弹性模量和拉伸强度显著增加，并且随着温度升高这种效果变得越来越显著。至于光氧化行为，二氧化硅的存在提高了聚丙烯基体的光稳定性。这种效果归因于二氧化硅纳米颗粒对氧气的阻隔作用以及对紫外线辐射的吸收。最后，未发现二氧化硅纳米颗粒对聚丙烯的结晶行为有显著影响。至于二氧化硅含量的影响，两种纳米复合材料性能的差异相对较小，并且所有测量性能与其含量的依赖关系远非线性关系。这与纳米颗粒的重新聚集有关，纳米颗粒尺寸较大，减少了基体与填料之间的接触面积。
