Effect of nanoclay loadings and reprocessing on dynamic mechanical thermal properties of polypropylene/nanoclay composites

Abstract

In the present work, polypropylene (PP)/nanoclay composites were fabricated by melt compounding nanoclay based masterbatch and PP pellets using a twin screw extruder (TSE). The compounding process was carried out at four different nanoclay loadings (i.e. 0, 5, 10, and 15 wt%) and two times processing i.e. 1st cycle and 2nd cycle. The fabricated nanocomposites were then characterized by using Scanning Electron Microscopy (SEM) and oscillatory rheometer. The SEM images showed that the nanoclay materials were well distributed in the PP matrix, which were indicated by the white needle-like appearance. Additionally, the dynamic mechanical thermal analysis (DMTA) results showed that the storage modulus of all the nanocomposites both 1st and 2nd cycles were higher than that of the neat PP, and increased with increasing nanoclay loadings. The improvement of storage modulus of the nanocomposites as compared to the neat PP (at temperature of 60°C) were approximately 56%, 84.3%, and 138% for NC-5-I, NC-10-I, and NC-15-I, respectively; and 62%, 89.6%, and 128% for NC-5-II, NC-10-II, and NC-15-II, respectively. While, tstorage modulus of all samples decreased with increasing temperature, which indicates than the nanocomposites simply behaved as polymeric material. Additionally, the relationship between the storage modulus, nanoclay loading (wt%), and temperature (°C) was successfully modeled by using Equation (1): G’ = Ae B(T) and Equation (2): A = 4.91E7 x (wt%) + 7.47E8, while B constant value was -0.0221.