Interfacial morphology of UHMWPE fiber reinforced LDPE composites

In order to realize the insert injection molding of polyethylene (PE) single-polymer composite (SPC), it is important to study the interfacial morphology of the matrix and reinforcement. In this study, the ultra-high molecular weight polyethylene (UHMWPE) fiber was used to reinforce low density polyethylene (LDPE) matrix. Thermodynamic properties of the fiber and matrix were tested by DSC. Polarizing microscope was adopted to simulate the molding process of PE SPC. The effects of different factors on the interfacial crystal morphology were investigated. The research results it could provide theoretical guidance for the insert-type injection molding process of PE SPC. The temperature range for the UHMWPE/LDPE composite was determined as 110.98~147.35℃ by the DSC results. Appropriate temperature and shear rate are conducive to the formation of interfacial transcrystallinity, which can produce better bonding between matrix and fiber and improve the mechanical properties of composites. Temperature has much greater influence than the shear, the injection temperature from 125 to 135℃ could be used to confirm the UHMWPE/LDPE composite without fiber melting. The effects on interface crystal morphology among fibers with each other are obvious, interfacial transcrystallinity could be found only around part filaments. It indicates that the structure of fiber bundles or fabric has great effect on the permeability of the matrix and the interface between the fiber and matrix.