Investigation of infusion of Ultra High Molecular Weight Polyethylene (UHMWPE) and Carbon Nanotube (CNT) into Low Density Polyethylene (LDPE) filaments

UHMWPE and CNT were infused into LDPE filaments to increase the strength, modulus and toughness of the filament. UHMWPE (8-10 wt%) and CNT (2-4 wt%) were dry mixed and filaments were drawn through a melt extrusion process using a laboratory mixing extruder. The idea was to use the unique properties of UHMWPE and CNT to enhance mechanical properties of LDPE which are largely used in industries. LDPE has been infused first with UHMWPE, and then with both UHMWPE and CNT, and filaments were extruded. Neat LDPE filaments were also extruded as control samples. Individual filaments from each category were tested under tension according to ASTM D3379-75. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies were conducted to measure changes in thermal and crystalline behavior. SEM analysis of the filament fracture process was also carried out. Filament tests have revealed that the tensile elongation of LDPE can be increased by about 200% with the addition of 10 wt% UHMWPE. This is, however, accompanied by a loss of about 50% ultimate tensile strength. In the next step, when 2 wt% CNTs and 8 wt% UHMWPE are added, tensile strength of the composite filament is restored to the level of neat LDPE (∼ 25 MPa) with an increase in modulus by 44% and in ultimate fracture strain by about 60% compared to that of neat LDPE.