Effect of Filler Loading on Curing Characteristic and Tensile Properties of Palygorskite Natural Rubber Nanocomposites

This work investigates the effect of filler loading on curing characteristics and tensile properties of palygorskite (PAL) natural rubber (NR) nanocomposites. The nanocomposites were prepared by using a combination of melt mixing and latex compounding method. Five different samples with different filler loading namely PAL2 (2 phr), PAL4 (4phr), PAL6 (6phr), PAL8 (8phr) and PAL10 (10 phr) were prepared in this work. All the samples were subjected to curing and tensile test. All the results were compared with pure gum of natural rubber. The curing characteristics of PAL/NR nanocomposites such as minimum and maximum torque were higher at optimum filler loading, PAL4. It means that the optimum filler loading would produce higher rigidity of the sample. Thus, PAL4 had higher stiffness compared to other filler loading. The scorch time and cure time of the sample that had undergone melt mixing and latex compounding method were higher compared to NR. The increase in both scorch time and cure time revealed that the presence of PAL could increase the curing process of the nanocomposites. Furthermore, PAL4 showed 18% increment in tensile strength. These results showed the optimum filler loading can increase the compatibility between PAL and NR. The size and shape of the PAL and the combination of melt mixing and latex compounding method might also contribute to this improvement. The morphology characteristics of all PAL/NR nanocomposites sample showed thicker tear line and rougher surface compared to control sample, NR. This might due to the homogenous dispersion of PAL which contains optimum filler loading. Thus, 4phr of palygorskite loading found to be the optimum filler loading with a combination of melt mixing and latex compounding methods.