Dynamic Rheology, Mechanical Performance, Shrinkage, and Morphology of Chemically Coupled Talc-Filled Polypropylene

作者：Jahani Yousef^*

来源：Journal of Vinyl & Additive Technology, 2010, 16(1): 70-77.

DOI：10.1002/vnl.20209

The oscillatory shear rheological properties, mechanical performance, shrinkage, and morphology of polypropylene (PP)-talc composites chemically coupled by maleic-anhydride-grafted polypropylene (MAPP) were studied. The samples were prepared in a co-rotating L/D = 40, 25 mm twin-screw extruder. Tensile tests carried out on injection-molded samples showed a reinforcing effect of talc up to 20 wt% on PP. Upon using MAPP, the mechanical performance of PP-30% talc showed a maximum of about 10% increase in tensile strength at 1.5 wt% of MAPP. A Newtonian plateau (eta(0)) at the terminal zone was observed for the complex viscosity curve of pure PP and PP-talc composites plotted against frequency up to 30 wt%. Upon increasing the talc content to 40 and 50 wt%, the complex viscosity at very low shear rates sharply increased and showed yield behavior that might be due to the formation of a network of filler agglomerates in the melt. Analysis of viscosity behavior in the power-law region revealed that the flow behavior index-n-decreased from 0.45 for 10 wt% of talc down to about 0.4 for 40 wt% of talc. Upon increasing the talc content to 50 wt%, n decreased to a value even lower than that of the neat PP resin. The frequency of the crossover point represents molecular mobility and relaxation-time behavior. The crossover frequency of the composites was nearly constant up to 30 wt% of talc and decreased at higher filler loadings. The optimum amount of coupling agent could be correlated with the minimum point in crossover frequency and crossover modulus. The shrinkage behavior of the composites with and without MAPP resin was studied and correlated with the rheological properties. J. VINYL ADDIT. TECHNOL., 16:70-77, 2010.

• 出版日期2010-3