It is believed that gel spun polyethylene(PE)fibers have a somewhat extended chain crystalstructure,because of the disentangling of the chains which takes place in semi-dilute solutionand the ultra high draw ratio use...It is believed that gel spun polyethylene(PE)fibers have a somewhat extended chain crystalstructure,because of the disentangling of the chains which takes place in semi-dilute solutionand the ultra high draw ratio used.Ten years ago,PE shish-kebabs grown from dilute solutionwere proved to have extended chain backbone which causes the raising of its melting point.These crystals were found to have a triclinic crystal phase,This study shows a different result forgel spun ultra high drawn PE fiber.The unit cell remains orthorhombic even if the draw ratioreaches 50;as the draw ratio increases,the length in a and b axes are shortened while that in c ax-is changes quite insignificantly.When the draw ratio is over 10,two endothermic melting peakscan be seen in the DSC curves with corresponding peak temperature of 136.7-145.3℃.The lat-ter peak is attributed to the amount of extended chain crystal.展开更多
The surface of high strength and high modulus polyethylene (PE) fiber has been modified bygrafting with acrylic acid.Benzophenone and acrylic acid in vapor phase were UV-irradiated in thepresence of the PE tiber subst...The surface of high strength and high modulus polyethylene (PE) fiber has been modified bygrafting with acrylic acid.Benzophenone and acrylic acid in vapor phase were UV-irradiated in thepresence of the PE tiber substrate.Grafting with acrylic acid took place in a thin layer on the sur-face,thus increasing the surface adhesion of PE fiber with epoxy resin.This paper dealt withphoto-polymerization reactions including the role of photoinitiator.The degree of graft increasedwith the enhancing of reaction time,reaction temperature and concentration of initiator.Acetonewas used as carriers of monomer and tiator and able to initiate and promote grafting to the sur-face.ATR-IR and SEM measurements on the grafted surface showed that some polar groups wereintroduced to the surface of PE fibers.Oligomer which existed during the polymerization could beremoved by washing with benzene.展开更多
Ultra-high strength and modulus polyethylene fibers can be produced from UHMW-PE(ul-tra-high molecular weight polyethylene) by gel spinning and ultra-high drawing method.The spe-cial supermolecular structure of″shish...Ultra-high strength and modulus polyethylene fibers can be produced from UHMW-PE(ul-tra-high molecular weight polyethylene) by gel spinning and ultra-high drawing method.The spe-cial supermolecular structure of″shish-kebabs″ is the intrinsic course for the fiber having highperformance.In this paper,the formation mechanism of the characteristic structure of PE fibershas been investigated by means of SEM,DSC,WAXD,SAXS and TEM,The experimental resultsshow that the extended-chain structure of PE fibers is formed originally from the bridged mole-cules in amorphous region and increased gradually during further drawing porcess.The″shish-kebab″ structure is formed by the combination of extended-chalnS and originalfolded-chains.展开更多
基金This project is supported by National Science Foundation of China
文摘It is believed that gel spun polyethylene(PE)fibers have a somewhat extended chain crystalstructure,because of the disentangling of the chains which takes place in semi-dilute solutionand the ultra high draw ratio used.Ten years ago,PE shish-kebabs grown from dilute solutionwere proved to have extended chain backbone which causes the raising of its melting point.These crystals were found to have a triclinic crystal phase,This study shows a different result forgel spun ultra high drawn PE fiber.The unit cell remains orthorhombic even if the draw ratioreaches 50;as the draw ratio increases,the length in a and b axes are shortened while that in c ax-is changes quite insignificantly.When the draw ratio is over 10,two endothermic melting peakscan be seen in the DSC curves with corresponding peak temperature of 136.7-145.3℃.The lat-ter peak is attributed to the amount of extended chain crystal.
文摘The surface of high strength and high modulus polyethylene (PE) fiber has been modified bygrafting with acrylic acid.Benzophenone and acrylic acid in vapor phase were UV-irradiated in thepresence of the PE tiber substrate.Grafting with acrylic acid took place in a thin layer on the sur-face,thus increasing the surface adhesion of PE fiber with epoxy resin.This paper dealt withphoto-polymerization reactions including the role of photoinitiator.The degree of graft increasedwith the enhancing of reaction time,reaction temperature and concentration of initiator.Acetonewas used as carriers of monomer and tiator and able to initiate and promote grafting to the sur-face.ATR-IR and SEM measurements on the grafted surface showed that some polar groups wereintroduced to the surface of PE fibers.Oligomer which existed during the polymerization could beremoved by washing with benzene.
文摘Ultra-high strength and modulus polyethylene fibers can be produced from UHMW-PE(ul-tra-high molecular weight polyethylene) by gel spinning and ultra-high drawing method.The spe-cial supermolecular structure of″shish-kebabs″ is the intrinsic course for the fiber having highperformance.In this paper,the formation mechanism of the characteristic structure of PE fibershas been investigated by means of SEM,DSC,WAXD,SAXS and TEM,The experimental resultsshow that the extended-chain structure of PE fibers is formed originally from the bridged mole-cules in amorphous region and increased gradually during further drawing porcess.The″shish-kebab″ structure is formed by the combination of extended-chalnS and originalfolded-chains.
