Preparation and characterization of UHMWPE/HDPE/MWCNT melt-blended nanocomposites

Abstract

The nanocomposite blends of ultra-high-molecular-weight polyethylene (UHMWPE) and high-density PE (HDPE) reinforced with 1 wt% of multi-wall carbon nanotube (MWCNT) were prepared by melt mixing at different compositions in an internal mixer. Two different grades of HDPE were used in this research to improve the processability of UHMWPE. Rheological, thermal, morphological, and mechanical properties were investigated for both (UHMWPE/HDPE) blends and their nanocomposites. The results confirmed the reduction in melt viscosity and improvement in the processability of UHMWPE by the addition of HDPE. Differential scanning calorimetry (DSC) results showed a single melting and crystallization peak, and the broadness of these peaks in blends compared to pure components indicated that two components form separate crystals. The effect of incorporating MWCNT to the blend samples on mechanical properties was studied, and the samples prepared with HDPE 5218 exhibited slight improvement in mechanical properties. Incorporating MWCNT into the blend of UHMWPE (20 wt%) accelerated crystallization; but in higher contents of UHMWPE, crystallization of the composites was slightly delayed. Rheological data exhibited lower complex viscosity and storage modulus and therefore lower elasticity for UHMWPE/HDPE/MWCNT nanocomposites compared to their blends. Drop in viscosity and storage modulus as well as tensile strength of nanocomposites compared to their blends was attributed to adsorption of higher molar mass polyethylene chains onto MWCNT surface. The morphology of nanocomposites was analyzed by scanning electron microscopy (SEM) and phase separation, and probably localization of MWCNT predominantly into HDPE matrix and HDPE/UHMWPE interface was concluded. X-ray diffraction (XRD) patterns indicated that MWCNT was well distributed and dispersed in HDPE matrix.