Preparation and Properties of Nano-Silica Filled Self-Reinforced Polypropylene
To improve the properties of polypropylene (PP), a new route that combines nanoparticles filling with self-reinforced technique was applied in this work. That is, nano-silica particles were firstly modified by graft polymerization to increase interfacial interaction between nanoparticles and matrix. Then the grafted nanoparticles were melt-compounded with PP producing composites sheets, and the sheets were stretched under a temperature slight lower than the melt point of PP at a constant velocity. Finally, the stretched sheets were film-stacked with random PP copolymer by a special designed mold and were hot pressd at different processing temperature (T=150-175°C) and holding pressure (2.0-5.0MPa) under constant holding time of 5min. The resultant self-reinforced nanocomposite are much stronger and stiffer than the unfilled polymer as characterized by mechanical test. The results show that the optimum processing conditions for hot consolidation are 160°C and 2.5MPa. Addition of nanoparticles increases crystallinity of PP, and induces the formation of craze and cause much more surrounding matrix polymer to involve in large-scale plastic deformation, which might ensure an overall improvement of mechanical properties.
Alan K.T. Lau, J. Lu, Vijay K. Varadan, F.K. Chang, J.P. Tu and P.M. Lam
W. H. Ruan et al., "Preparation and Properties of Nano-Silica Filled Self-Reinforced Polypropylene", Advanced Materials Research, Vols. 47-50, pp. 318-321, 2008