Effect of clay amount and reprocessing cycles on thermal, morphological, and mechanical properties of polypropylene/organovermiculite nanocomposites

摘要

Nanocomposites of polypropylene (PP) and PP-grafted-maleic anhydride (PP-g-MA) with and without organophilic vermiculite (OVMT) (5-8%w/w) were evaluated. The nanocomposites and neat PP were submitted to extrusion reprocessing cycles. It was found that the presence of OVMT in PP/PP-g-MA was critical for maintaining thermal stability during reprocessing. The exfoliation/intercalation was confirmed, mainly, in the nanocomposite submitted to reprocessing cycles, by X-ray diffraction. The melt flow index (MFI) values for the 3x and 5x reprocessed PP increased by 40% and 70%, respectively, as compared to the neat PP. The MFI for the 3x and 5x reprocessed PP/PP-g-MA/OVMT decreased 26% and 17%, respectively, as compared to the decrease occurred in the 3x and 5x reprocessed PP, indicating that the presence of 5% (w/w) OVMT was sufficient to allow an increase in viscosity. The reprocessed nanocomposites exhibited values for tensile and flexural strengths and Izod impact, in general, greater than or near to those of PP with the same number of reprocessing cycles. The increase or maintenance of mechanical properties seems to depend on a balance between the extent of intercalation/exfoliation and dispersion of OVMT in the PP matrix, and the degree of degradation of the PP matrix. POLYM. ENG. SCI., 2019. (c) 2019 Society of Plastics Engineers