the effect of molecular weight on the toughness of sintered polyethylene

In recent decades, there has been a substantial surge in scholarly attention directed towards unraveling the intricacies of the sintering process, particularly in its role as a pivotal phenomenon in the fabrication products of ceramic or metallic powders with high melting points. the confluence of technological progress and the adoption of innovative powder-based methodologies for shaping polymers, for example, powder bed fusion additive manufacturing, has significantly broadened the scope of the investigation, extending the understanding of sintering to encompass polymer systems. in these studies, the main efforts were focused on reducing the possible porosity in the final part, as a structural defect. today, with the increasing development of the use of porous polymer structures in various industries, the use of the sintering process in order to benefit from the remaining porosity in the sintered parts and achieve porous polymer structures has also been considered. the sintering phenomenon in polymer materials is implied by the coalescence of powder particles achieved through the application of heat, to before the point of complete melting and the formation of a cohesive mass. this event stands as a fundamental and highly effective step in various manufacturing processes involved in polymer part fabrication. among these are rotational molding and additive manufacturing techniques such as selective laser sintering, both of which leverage the sintering process to achieve desirable material. recognizing that a nuanced and comprehensive understanding of any given phenomenon is contingent upon a meticulous examination of the influencing factors, the core objective of this project is to investigating the impact of polymer molecular weight on the ultimate quality of the porous sintered samples. the importance of the toughness exhibited by the final manufactured parts as a critical metric in assessing functional quality becomes apparent, prompting the central focus of this research on evaluating the toughness characteristics. specifically, the shear punch test serves as a tool for in-depth scrutiny of toughness variations in a sintered polyethylene piece with differing molecular weights, namely very low and high molecular weights. the findings of this investigation unveil a noteworthy enhancement in the quality of polyethylene powder particles coalescing with an increase in molecular weight. this observation substantiates the paramount role of molecular weight in the movement of molecular chains and the integration of primary powder particles. in order to delve even deeper into the physical nature of events occurring during the sintering process, the study extends to the evolutions of melting and crystallization. these dynamic processes are systematically examined through the application of techniques such as differential scanning calorimetry (dsc). in summation, the elucidation of sintering-related phenomena is enriched by an exhaustive exploration into the interplay between variations in molecular weight and the resultant toughness characteristics observed in polymer materials. it was observed that with the increase of sintering time while the crystals evolve, the punch strength and toughness increase. this increase in the initial stages of sintering was insignificant and almost independent of molecular weight, but with the increase of sintering time, the toughness increased and this increase in polyethylene with high molecular weight is significantly higher than polyethylene with very low molecular weight.