Kenji Yamada

Plasma-graft polymerization of vinyl monomers with reactive groups onto a surface of poly(p-phenylene terephthalamide) fiber

The mechanical properties of a fiber-reinforced plastic are influenced by the adhesion between a reinforcing fiber and a matrix resin. In this work we tried to obtain strong adhesion between Kevlar 49TM yarn and a matrix resin through the formation of covalent bonds. Reactive groups were introduced onto a surface of the yarn by means of plasma-graft polymerization and then reacted with an epoxy resin/curing agent mixture as a matrix resin to form covalent bonds. Glycidyl methacrylate and acrylamide were used as mono-mers for plasma-graft polymerization. The degree of grafting was increased with increasing polymerization time. The grafted yarns enclosed with diglycidal ether of bisphenol-A/tri-ethylenetetramine 2.2 : 1 mixture were pulled out to obtain pull-out force after curing. The pull-out force increased with increasing degrees of grafting. The covalent bonds formed between the graft polymer and the matrix resin result in an increment of pull-out force.

Plasma‐graft polymerization of vinyl monomer with an acid amide group onto a surface of carbon fiber and its adhesion to epoxy resin

The mechanical properties of a fiber-reinforced plastic are influenced by the adhesion between a reinforced fiber and a matrix resin. In this work it is shown how to obtain strong adhesion between a carbon yarn and an epoxy resin through the formation of covalent bonds. Acid amide groups reactive with epoxy groups were introduced onto a surface of the yarn by means of plasma-graft polymerization of acrylamide. The density of active radicals formed on a surface of the yarn by the plasma irradiation was first increased with increasing discharge power and plasma irradiation time, and then the rates of the increase were largely decreased. The degree of grafting was linearly increased with increasing the surface density of active radicals. The yarn embedded in diglycidyl ether of bisphenol-A/triethylenetetramine mixture was pulled out to obtain pull-out force after curing. Pull-out force was increased with increasing degree of grafting and the failure in pulling out of the yarn was cohesive. The covalent bonds formed in the graft layer will result in an increment of pull-out force.

Preparation of superabsorbent polymer hydrogels from trialkyl‐4‐vinylbenzyl phosphonium chloride–acrylamide–methylenebisacrylamide terpolymers and their properties

Superabsorbent polymer gels were synthesized by terpolymerization of three kinds of tri-n-alkyl-4-vinylbenzyl phosphonium chloride (TRVB) with alkyl chains of different lengths, with acrylamide (AAm), and with N,N′-methylenebisacrylamide (MBAAm). The water-absorption ability and antibacterial activity of the gels against Staphylococcusaureus (S. aureus) and Escherichia coli (E. coli) were investigated. The water content of TRVB–AAm–MBAAm terpolymers increased with increasing phosphonium groups in the terpolymers, while the water content decreased with increasing chain length of alkyl groups in the phosphonium groups as well as an increasing degree of crosslinking in the terpolymers. The water content of the terpolymers was depressed by the addition of NaCl. The degree of effect of NaCl addition became higher as the chain length of alkyl groups in the phosphonium groups of the terpolymers became longer. The tri-n-octyl-4-vinylbenzyl phosphonium chlorides (TOVB)–AAm–MBAAm terpolymers exhibited high antibacterial activity against S. aureus and E. coli in deionized water. The antibacterial activity decreased in 0.9 wt % NaCl solution. The antibacterial activity of TOVB–AAm–MBAAm terpolymers with almost the same phosphonium content increased with the increasing swelling ratio of the terpolymers.