Abstract
In the present study, different series of High Density Polyethylene (HDPE)/nanoclay composites were prepared using melt blending in a co-rotating intermeshing twin screw extruder. For developing composite material, commercial injection molding grade HDPE was physically mixed with nanoclay
particles (Montmorillonite P-801, MMT) in the ratios of 0, 3, 6 and 9 wt% and fed on Farrell co-rotating intermeshing twin screw extruder at 12 rpm and 190 °C and conditioned to get standard ASTM D638 type I specimen. The morphological observation showed a clear dispersion of nanoclay
in HDPE and increased surface roughness with increasing percentages. The X-ray diffraction results indicated no phase change of HDPE due to the addition of nanoclay however a slight decrease in crystallinity and increased FWHM is noticed. FTIR studies indicated interaction between HDPE and
nanoclay by forming a broad band from 790 to 806 cm-1 due to the CH2 starching and O-H group at 3350 cm-1. Thermal characterization indicated degradation of all HDPE/nanoclay samples begins at about 370 °C, while the initial decomposition
temperature of pure HDPE is at about 429 °C indicating reduced thermal stability with increasing nanoclay percentage. The nano-mechanical properties was studied as a function of strain rates of 1, 2 and 4 s-1 that resulted in increased hardness and elastic modulus. Similarly,
the nano-indentation test results showed that the elastic modulus and hardness increases with increasing the loading of nanoclay. Addition up to 6 wt% of nanoclay increases load bearing capacity to a maximum load of 16 mN while 9 wt% deteriorates the maximum load to 14 mN. The changes due
to nanoclay incorporation resulted in the altered mechanical properties of HDPE/nanoclay composites due to decrease of free volume and hence restricted mobility because of the cationic properties of MMT.