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Journal Articles

Effect of partial delignification of kenaf bast fibers for radiation graft copolymerization

Mohamed, N. H.*; Tamada, Masao; Ueki, Yuji; Seko, Noriaki

Journal of Applied Polymer Science, 127(4), p.2891 - 2895, 2013/02

https://doi.org/10.1002/app.37512

Times Cited Count：13 Percentile：37.82(Polymer Science)

Changes in residual lignin of kenaf bast fiber with acidic chlorite using various parameters were conducted to produce partial delignified fiber for radiation graft copolymerization. The effect of delignification temperature, operating time as well as chlorite doses on the residual lignin of the fibers has been reported. Results obtained indicated that the optimal delignification was achieved at 80 $^{circ}$ C for 6h with 0.5% chlorite. The reduction in density, size and tensile strength were attributed to the increase of removal of lignin from the fiber. Radiation induced emulsion graft copolymerization of 4-chloromethyl styrene (CMS) on partial delignified kenaf with residual lignin 2% resulted in higher degree of grafting of about 143% as compared to the undelignified fiber, which showed the absence of grafting degree.

Journal Articles

Surface modification of vulcanized rubber by radiation grafting, 2; Improvement in performance of wiper rubber

Mizote, Norihito*; Katakai, Akio; Tamada, Masao

Journal of Applied Polymer Science, 123(4), p.2172 - 2176, 2012/02

https://doi.org/10.1002/app.34736

Times Cited Count：5 Percentile：16.89(Polymer Science)

Surface of natural rubber was modified by radiation-induced grafting of 2-hydroxyethyl methacrylate (HEMA) to improve the properties of surface hardness, dry friction, wiping performance, and wear duration. The composition ration of HEMA to rubber was controlled from 0.29 to 0.93 by changing HEMA concentration and dose in graft polymerization. When this composition ration was higher than 0.7, the surface hardness was higher than 64 and the coefficient of dry friction lower than 0.65. Those values became better than those of commercially available chlorinated-rubber in terms of wear and friction against glass. The resulting wear resistance was 10 times higher than chlorinated rubber. However, the surface hardness in wet state was 62.5 since grafted-HEMA gave the hydrophilicity to the rubber. As a result, the grafted-HEMA rubber realized 95% and higher wiping performance of water on glass.

Journal Articles

Surface modification of vulcanized rubber by radiation grafting, 1; Improvement in friction behavior

Mizote, Norihito*; Katakai, Akio; Tamada, Masao; Matsuoka, Hiroshige*

Journal of Applied Polymer Science, 117(5), p.2825 - 2830, 2010/09

Hydrophilic monomer, 2-hydroxyethyl methacrylate (HEMA), and hydrophobic monomer, 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane (MPTS), were grafted on vulcanized rubber surface by simultaneous electron beam irradiation. We studied the characteristics of graft polymerization, the relationship between the contact angle of water on the modified surface and friction behavior at the moment of semi-dry. Grafted rubbers were investigated with composition ratio and contact angle. As a result of graft polymerization of HEMA and MPTS, the composition ratio increased as the monomer concentration and the irradiation dose increased. By the graft polymerization of HEMA, the contact angle decreased to approximately 70 $^{circ}$ . By the graft polymerization of MPTS, the contact angle increased approximately to 108 $^{circ}$ . Friction behavior at the moment of semi-dry was evaluated by which is difference with the coefficient of dry friction and maximum friction. The increase in the contact angle owing to hydrophobic properties by graft polymerization of MPTS led to the decrease of . The decrease in the contact angle owing to hydrophilic properties by graft polymerization of HEMA resulted in the increase of .

Journal Articles

Polymer electrolyte membranes having sulfoalkyl grafts into ETFE film prepared by radiation-induced copolymerization of methyl acrylate and methyl methacrylate

Hanh, T. T.*; Takahashi, Shuichi; Chen, J.; Sawada, Shinichi; Maekawa, Yasunari

Journal of Applied Polymer Science, 114(1), p.231 - 237, 2009/06

https://doi.org/10.1002/app.30458

Times Cited Count：6 Percentile：21.63(Polymer Science)

Polymer electrolyte membranes (PEMs) containing alkylsulfonic acid grafts can be prepared by radiation-induced graft copolymerization of methyl acrylate (MA) and methyl methacrylate (MMA) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film followed by sulfonation of the MA units in the copolymer grafts using an equimolar complex of chlorosulfonic acid and 1,4-dioxane (ClSO $_{3}$ H-Complex). The grafted films with 33-79 % MA units are treated with ClSO $_{3}$ H-Complex to obtain PEMs with IEC of 0.36-0.81 mmol/g and proton conductivity of 0.04-0.065 S/cm. The PEMs with higher MMA content showed higher durability in water (80 $^{circ}$ C) and under oxidative conditions (3% H $_{2}$ O $_{2}$ ) at 60 $^{circ}$ C. This is because the PMMA grafts in the PEMs have no proton at an -carbonyl carbon, which is considered to be a trigger of the degradation of grafting polymers.

Journal Articles

Improvement of poly(vinyl alcohol) properties by the addition of magnesium nitrate

Kubo, Junichi*; Rahman, N.*; Takahashi, Nobuaki; Kawai, Takahiko*; Matsuba, Go*; Nishida, Koji*; Kanaya, Toshiji*; Yamamoto, Masahide*

Journal of Applied Polymer Science, 112(3), p.1647 - 1652, 2009/05

https://doi.org/10.1002/app.29561

Times Cited Count：25 Percentile：62.54(Polymer Science)

Aiming at improvement of mechanical and dielectric properties of poly(vinyl alcohol) (PVA) we prepared composites of PVA and magnesium nitrate. It was found that the composites were very soft and rubber-like, and the glass transition temperature decreased with increasing the salt concentration. Wide-angle X-ray diffraction and small-angle X-ray scattering revealed that the crystallites of PVA were destroyed by the additive and it was a cause of the softening.

Journal Articles

Radiation-induced crosslinking and mechanical properties of blends of poly(lactic acid) and poly(butylene terephthalate--adipate)

Sarath Kumara, P. H.*; Nagasawa, Naotsugu; Yagi, Toshiaki; Tamada, Masao

Journal of Applied Polymer Science, 109(5), p.3321 - 3328, 2008/09

https://doi.org/10.1002/app.28402

Times Cited Count：21 Percentile：54.36(Polymer Science)

Blends of poly(L-lactic acid) (PLLA) and poly(butylene terephthalate--adipate) (PBTA) were prepared at ratios of 50:50, 60:40, and 80:20 by melt blending in a Laboplastomill. Improved mechanical properties were observed in PLLA when it was blended with PBTA, a biodegradable flexible polymer. Irradiation of these blends with an electron beam (EB) in the presence of triallyl isocyanurate (TAIC), a polyfunctional monomer, did not cause any significant improvement in the mechanical properties, although the gel fraction increased with the TAIC level and dose level. Irradiation of the blends without TAIC led to a reduction in the elongation at break but did not show asignificant effect on the tensile strength. The elongation at break of PBTA was unaffected by EB radiation in the absence of TAIC.

Journal Articles

Emulsion grafting of vinyl acetate onto preirradiated poly(3-hydroxybutyrate) film

Wada, Yuki*; Tamada, Masao; Seko, Noriaki; Mitomo, Hiroshi*

Journal of Applied Polymer Science, 107(4), p.2289 - 2294, 2008/02

https://doi.org/10.1002/app.27219

Times Cited Count：14 Percentile：42.12(Polymer Science)

Vinyl acetate (VAc) was grafted onto poly(3-hydroxybutyrate) (PHB) film by preirradiation method. Grafting reactions were carried out in a VAc/water/surfactant emulsion, VAc/water, and VAc/methanol systems. For emulsion grafting, Nonion L-4 was ascertained to be the optimum surfactant with regard to the stability of a single emulsion layer. The emulsion with a 10:1 (w/w) ratio of VAc and surfactant yielded the highest degree of grafting (Xg) 23%. The grafting efficiency in the emulsion and the water and methanol solvent were evaluated. The results indicated that the grafting efficiency of the emulsion is 100 times that of VAc/methanol when the same 2 wt% VAc was used in the grafting reaction.

Journal Articles

Oriented crystallization of crosslinked -1,4-polybutadiene rubber

Saijo, Kenji*; Zhu, Y.*; Hashimoto, Takeji; Wasiak, A.*; Brzostowski, N.*

Journal of Applied Polymer Science, 105(1), p.137 - 157, 2007/07

https://doi.org/10.1002/app.26019

Times Cited Count：15 Percentile：44.09(Polymer Science)

Crosslink -1,4-polybutadiene (PB) rubber is known to undergo crystallization during mechanical deformation. This article presents small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and stress-relaxation studies of the structural development in crosslinked PB samples crystallized under various orientation regimes. The studies are concerned with isothermal crystallization at various temperatures (10 to -50 $^{circ}$ C) and at constant elongation ratios (1-4,5) and hence with the effects of weak -to-intermediate and high orientations on oriented crystalliation versus the behavior of unoriented specimens. Although the crystallization in the weak-to-intermediate orientations is interpreted on the basis of nucleation growth, the crystallization under high orientations is best interpreted on the basis of spinodal crstallization. To the best of our knowledge, this work reports for the first time spinodal-like crystallization on oriented crosslinked polymer melts.

Journal Articles

Comparative study on the preparation and properties of radiation-grafted polymer electrolyte membranes based on fluoropolymer films

Chen, J.; Septiani, U.*; Asano, Masaharu; Maekawa, Yasunari; Kubota, Hitoshi*; Yoshida, Masaru

Journal of Applied Polymer Science, 103(3), p.1966 - 1972, 2007/03

https://doi.org/10.1002/app.24950

Times Cited Count：20 Percentile：53.03(Polymer Science)

In this study, ETFE and PVDF films, together with the crosslinked PTFE (cPTFE) films have been compared on the basis of their preparation and properties of radiation-grafted polymer electrolyte membranes (PEM). The proton conductivity and chemical stability of the three types of membranes with the similar ion exchange capacity near 1.0 mmolg $^{-1}$ were investigated and discussed in detail. Although the ETFE-based PEM was relatively more stable, its proton conductivity was lower than those of the PVDF- and cPTFE-based membranes. On the other hand, the cPTFE-based membrane showed the significantly higher proton conductivity, but its chemical stability was shorter than that of the ETFE-based membrane. The difference in the preparation and properties of the PEMs was due to the difference in the crystallinity and intrinsic properties of the base films.

Journal Articles

Control of biodegradability of poly(3-hydroxybutyric acid) film with grafting acrylic acid and thermal remolding

Wada, Yuki; Mitomo, Hiroshi*; Kasuya, Kenichi*; Nagasawa, Naotsugu; Seko, Noriaki; Katakai, Akio; Tamada, Masao

Journal of Applied Polymer Science, 101(6), p.3856 - 3861, 2006/09

https://doi.org/10.1002/app.24189

Times Cited Count：21 Percentile：53.63(Polymer Science)

Radiation-induced graft polymerization of acrylic acid (AAc) on the surface of poly(3-hydroxybutyric acid) (PHB) film was carried out by applying pre-irradiation techniques. The PHB films grafted with AAc (PHB-g-AAc) possessed a degree of grafting higher than 5% have completely lost the enzymatic degradability. The enzymatic degradability of the grafted film was recovered by remolding. And the highest enzymatic degradation rate was observed to grafted films with AAc 10% of degree. Difference of enzymatic degradability of PHB-g-AAc film was caused by decrement of amount of enzyme contact and decrement of crystallinity of PHB by remolding.

Journal Articles

Preparation and properties of sulfonated ETFE--polyvinyltoluene membranes for application in fuel cells

Chen, J.; Asano, Masaharu; Yoshida, Masaru; Maekawa, Yasunari

Journal of Applied Polymer Science, 101(4), p.2661 - 2667, 2006/08

https://doi.org/10.1002/app.23909

Times Cited Count：27 Percentile：61.61(Polymer Science)

A new polymer electrolyte membrane prepared by radiation grafting of vinyltoluene into poly(ethylene-co-tetrafluoroethylene) (ETFE) film and subsequent sulfonation was developed for the application in fuel cells. The effect of grafting condition on the degree of grafting was investigated in detail. Results indicated that the degree of grafting can be controlled over a wide range. The grafted films were sulfonated in a chlorosulfonic acid solution to obtain the polymer electrolyte membranes, which were characterized with respect of their use in fuel cells. It is concluded that the substituted methyl group on the vinyltoluene can improve the chemical stability of the resulting membranes, and the crosslinked ETFE--poly(vinyltoluene-co-divinylbenzene) membranes can be proposed for the future development of alternative low cost and high performance membranes for fuel cells.

Journal Articles

Effect of crosslinkers on the preparation and properties of ETFE-based radiation-grafted polymer electrolyte membranes

Chen, J.; Asano, Masaharu; Yamaki, Tetsuya; Yoshida, Masaru

Journal of Applied Polymer Science, 100(6), p.4565 - 4574, 2006/06

https://doi.org/10.1002/app.22567

Times Cited Count：44 Percentile：75.8(Polymer Science)

This study concerns a comparative study of three crosslinkers, divinylbenzene (DVB), 1,2-bis(p,p-vinylphenyl)ethane (BVPE) and triallyl cyanurate (TAC) crosslinked poly(ethylene-co-tetrafluoroethylene) (ETFE)-based radiation-grafted membranes, which were prepared by radiation grafting of p-methylstyrene (MeSt) onto ETFE films and subsequent sulfonation. The effect of the different types and contents of the crosslinkers on the grafting and sulfonation, and the properties such as water uptake, proton conductivity and thermal/chemical stability of the resulting polymer electrolyte membranes was investigated in detail. Introducing crosslink structure into the radiation-grafted membranes leads to a decrease in proton conductivity due to the decrease in water uptake. The thermal stability of the crosslinked radiation-grafted membranes is also somewhat lower than that of the noncrosslinked one. However, the crosslinked radiation-grafted membranes show significantly higher chemical stability characterized in the 3% H $_{2}$ O $_{2}$ at 50 $^{circ}$ C. Among the three crosslinkers, the DVB shows a most pronounced efficiency on the crosslinking of the radiation-grafted membranes, while the TAC has no significant influence; the BVPE is a mild and effective crosslinker, showing the moderate influence between the DVB and TAC crosslinkers.

Journal Articles