Abstract
The versatility of high-density polyethylene (HDPE) makes it one of the most used polymers for vast applications ranging from food packaging to human implants. However, there still is confusion regarding the proper selection of processing techniques to produce HDPE specimens for high-end applications. Herein, we compare the processing of HDPE by two relevant techniques: compression and injection molding. The fabricated samples were studied using uniaxial tensile testing to determine their mechanical performance. Furthermore, the microstructure of samples was analyzed using different characterization techniques. Compression-molded specimens recorded a higher degree of crystallinity (DC) using two different characterization techniques such as differential scanning calorimetry (DSC) and X-ray diffraction (XRD). With this information, critical processing factors were determined, and a general structure–property relationship was established. It was demonstrated that having a higher DC resulted in higher yield strength and Young’s modulus. Furthermore, premature failure was observed in the injection-molded specimens, resulting in lower mechanical performance. This premature failure was caused due to flow marks observed using scanning electron microscopy (SEM). Therefore, it is concluded that compression molding produces superior samples compared to injection molding.
Highlights
IntroductionPolyethylene with general formula (C2 H4 )n is one of the most commonly used polymers due to its chemical inertness, low cost, and strength [1,2,3,4,5]
The high-density polyethylene (HDPE) used in this study was obtained from SigmaAldrich, Missouri, MO, USA with a melt index of 2.2 g/10 min
The raw material used for both injection molding and compression molding was pure
Summary
Polyethylene with general formula (C2 H4 )n is one of the most commonly used polymers due to its chemical inertness, low cost, and strength [1,2,3,4,5]. Properties of polyethylene vary significantly due to the number of different chain architectures and molecular weights and are highly dependent on the synthesis process. The most ubiquitous variants of polyethylene and its derivatives are polytetrafluoroethylene (PTFE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and ultra-high molecular weight polyethylene (UHWWPE) [6,7,8,9]. HDPE has received worldwide attention due to its unique properties such as high strength to weight ratio, high impact resistance, durability, 4.0/)
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