Influence of sequential melting and sintering process on morphology development and performance properties of ultra‐high molecular weight polyethylene/low‐density polyethylene blends

Abstract

AbstractBlending ultra‐high molecular weight polyethylene (UHMWPE) with a low molecular weight polyolefin is a well‐established technique to improve its processability. The binary blends of UHMWPE and low‐density polyethylene (LDPE) were prepared with varying LDPE content (10%, 20%, 30%, 40%, and 50% by wt.) leading to the formation of a single polymer composite system (SPCS) as melting and sintering followed preferential stages during mixing. Interestingly, the sequence of either “melting followed by sintering” or “simultaneous sintering and melting” depends on the LDPE content in the blend, resulting in unique blend morphology. Separate melting peaks for the blend's constituents were observed in thermal characterization, showing the blend's immiscibility, while intermediate peaks showed moderate miscibility in the melt state. Due to the high entanglement density, UHMWPE retained a solid‐like structure and showed an intense viscous nature even above the melting point in rheological characterization. Typically, the UHMWPE samples are fabricated by boundary fusion between particles called sintering. At LDPE content higher than 30 wt.%, the sea island structure was visible in morphological analysis, and the preexisting cavities reduced the tensile modulus by 54% in the blend, along with decreased elongation at failure (250%–100%). Similarly, the flexural modulus was reduced by 34.7% in the blends, along with the decreased flexural strength. Interestingly, the decrease in performance properties occurred in two steps over the range of LDPE content. Thus, it was clear that 30 wt.% of LDPE in the UHMWPE/LDPE blend represented the critical concentration for controlling melting and sintering sequence to develop specified morphology and performance properties. These blends have the potential for biomedical application as well as for the development of foam products, which is the further scope of the present study.