Preparation of Ultra High Molecular Weight Polyethylene Fiber Reinforced Composite Tapes Using Solution Impregnation Technique
|Course||Materials Processing Engineering|
|Keywords||Solution Impregnation Technique Ultra High Molecular Weight Polyethylene Fiber Polypropylene High Density Polyethylene Composite Tapes|
With the rapid development of the modern science and technology, people’s dependence on communication network and information transmission is growing, and it is necessary to protect the optical cable with high strength components. In order to keep communication network unobstructed and reliable, researchers have invented high strength fiber reinforced tape which is applied as the reinforcement of optical cable.In this paper, ultra high molecular weight polyethylene (UHMWPE) fiber with light weight, high strength and high modulus, is taken as reinforcing fiber. Polypropylene (PP) and high density polyethylene (HDPE) are taken as resin matrices and dissolved in decalin to prepare impregnation solutions. UHMWPE fibers reinforced composite tapes are prepared on self-made composite tape molding machine by using solution impregnation under atmospheric pressure and high pressure respectively. Thermal properties, crystal structure and surface morphology of composite tape are characterized by means of differential scanning caborimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscope (SEM), meanwhile mechanical and dynamic mechanical properties are analyzed through electronic tensile tester and dynamic mechanics thermal analyzer, to optimize the processing conditions.Because of the dissolving and etching of heated decalin, the surface of UHMWPE fiber becomes rough, and some grooves occur on the fiber’s face. The roughness increases and then decreases with the increase of decalin temperature. Melting temperature and crystallinity of UHMWPE fiber treated by heated decalin increase and then decreases with the increase of treating temperature. The changes in the melting temperature and crystallinity of UHMWPE fiber in UHMWPE/PP tape show the same trend. While that of PP-matrix in UHMWPE/PP tape prepared and the overall values of UHMWPE/HDPE tapes all decrease with the increase of treating temperature. There are no obvious changes on crystal structure of UHMWPE fiber and the matrix, after treated by pure decalin, PP/decalin and HDPE/decalin solution. The crystal sizes reduce with the increase of treating temperature.Based on Weibull statistical distribution, statistics strength and shape parameter of different composite tapes can characterize the average value and distribution of the tensile strength of composite tapes, so that we can choose optimal processing conditions. Statistics strength and its distribution of UHMWPE fiber heated by pure decalin, decrease with the increase of decalin temperature, and increase with the increase of winding speed. The optimal processing conditions of UHMWPE/PP composite tape prepared under atmospheric pressure are:the concentration of PP/decalin solution 20%, heat treatment temperature 125℃, and winding speed 8mm/s. The optimal processing conditions of UHMWPE/HDPE composite tape prepared under atmospheric pressure are:the concentration of HDPE/decalin solution 5%, heat treatment temperature 125℃, and winding speed 8mm/s. The optimal processing conditions of UHMWPE/HDPE composite tape prepared with high pressure are:the concentration of HDPE/decalin solution 8%, solution pressure 50kPa, heat treatment temperature 125℃, and winding speed 400mm/s.In the process of preparing composite tapes, UHMWPE filaments are bonded by resin matrix, avoiding the uneven distribution of tensile force in UHMWPE filaments when the fiber bundles are stretched, therefore the actual strength is higher than theoretical values. The creep elongation of composite tapes increase with the increase of load, and the overall creep keeps at a low level. And the creep resistance of UHMWPE/HDPE composite tapes prepared under high pressure is better than that of UHMWPE/PP composite tapes prepared under atmospheric pressure. The DMA results of different composite tapes show that, when the PP concentration of atmospheric pressure solution is 20% or the HDPE concentration of high pressure solution is 8%, the interfacial bonding in the composite tapes prepared under those processing conditions is the best.