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Volume 65, Issue 2
Displaying 1-14 of 14 articles from this issue
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Review Articles
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Masamitsu SHIRAI2008 Volume 65 Issue 2 Pages 113-123
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSPhotocrosslinkable or UV curable reins are significant materials thanks to the applications for coatings, adhesives, photoresists, and printing plates. The crosslinked polymers are insoluble in solvents and are infusible. It is very difficult or impossible to remove the crosslinked materials from substrates. Recently, however, much attention has been paid to recovery or recycling of crosslinked polymers due to environmental regulations. From this point of view, photocrosslinkable polymers with reworkable properties have been studied. Reworkable photopolymers are also realized as highly functionalized photopolymers. In this article the recent research work on photocrosslinkable polymers with reworkable properties is reviewed, together with reworkable thermosets.
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Original Papers
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Minoru KOBAYASHI, Shiho OHUCHI, Hisaya SATO2008 Volume 65 Issue 2 Pages 124-131
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSChemical compositions and those distributions of styrene (St)-methyl acrylate (MA) and St-ethyl acrylate (EA) copolymers synthesized by emulsion copolymerization under different polymerization conditions were examined by 1H NMR and HPLC, respectively, results were compared with those of bulk copolymers. MA or EA fraction at early stage decreased with the increase of emulsifier concentration ([SDS], sodium dodecyl sulfate) and converged to the value calculated using the distribution factor (fd) when SDS concentration is extrapolated to zero. In St-MA copolymer, furthermore, MA fraction decreased with the increase of polymerization rates (Rp) and converged to the value from fd when Rp is zero. These results indicate that the MA or EA monomer fraction in micelle decreased compared to the expected value from fd due to the interaction of hydrophilic monomer with emulsifier and/or the diffusion-controlled process. From HPLC studies, it was found that no homopolymer or copolymer with different composition was produced.
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Kohei SHIRAISHI, Tetsuyuki SHIGESADA, Kazuhiko YAMAMOTO, Kazuo SUGIYAM ...2008 Volume 65 Issue 2 Pages 132-139
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSIn order to develop a more precise evaluation method for the application as a cell scaffold, the surface of thermoresponsible poly(N-isopropylacrylamide) (PNiPAAm) grafted PET (g-PET) was characterized by a bacterial random peptide library method (FliTrxTM: Invitrogen). The g-PET was prepared by an Ar plasma-post polymerization method. From the analysis of selective 12 amino acids sequences, we could observe that the surface of g-PET was hydrophilic at 25°C and hydrophobic surface at 37°C, respectively. In addition, the Kyte & Doolittle parameter of g-PET was -67.6 on hydrophilic surface at 25°C and -28.4 for the hydrophobic surface at 37°C. On the other hand, the Kyte & Doolittle parameter of the untreated PET was 34.3 at 25°C and 42.2 at 37°C, respectively. The Selection of amino acids sequences changed drastically on the g-PET by raising the panning temperature from 25°C to 37°C.
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Takanobu KATSUMATA, Hiroaki KOUZAI2008 Volume 65 Issue 2 Pages 140-144
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSNew polyurethanes were obtained from novel diols with a biphenyl group and various diisocyanates BPS6. The corresponding polyurethanes, whose inherent viscosities range from 0.36 to 0.42 dL/g, were obtained in moderate to high yields (62~82%). Structural characterization was carried out by elemental analysis, FT IR spectroscopy and nuclear magnetic resonance (1H NMR) spectroscopy. Optical and thermal methods reveal that this polyurethane exhibits enantiotropic mesomorphic behavior. Differential scanning calorimetry (DSC) shows a crystalline melting transition that is highly dependent on the molecular weight. The polyurethane prepared from triethyleneglycol diisocyanate and BPS6 has a wide rubbery plateau region at -10~120°C and good vibration absorbency.
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Kenichi OYAIZU, Hidenori MURATA, Daisuke YOSHII, Takehiro ISHIKAWA, Ma ...2008 Volume 65 Issue 2 Pages 145-149
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSThe oxidative polymerization of 2,6-dimethylphenol is a convenient engineering method to synthesize poly(2,6-dimethyl-1,4-phenylene ether) (PPE) as a high-performance engineering plastic in industrial fields. Recently, we reported the novel synthesis of PPE diblock copolymers based on the analysis of the polymerization mechanism. We report the preparation of PPE diblock copolymers bearing carboxylic or sulfonic acid as acid substituents. The resulting acid substituented PPE block copolymers, poly(2,6-dimethyl-1,4-phenylene ether- block-2-carboxy-6-methyl-1,4-phenylene ether) 3 and poly[2,6-dimethyl-1,4-phenylene ether-block-2-phenyl-6-(4-sulfophenyl)-1,4-phenyl- ene ether] 5, were applied as polymer electrolyte membranes for fuel cells. 3 and 5 were soluble in polar organic solvents such as N,N-dimethylformamide, dimethylsulfoxide, and THF and gave tough membranes by casting. Sulfonated polymer 5 membrane showed high ion exchange capacity and high oxidative stability. The results suggested that the acid substituents attached onto the pendant phenyl groups were more stable than those on main chains.
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Nobuyuki TANIGAWA, Kohei SHIRAISHI, Kazuo SUGIYAMA2008 Volume 65 Issue 2 Pages 150-156
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSBlock copolymers, poly(LysMA-b-DMS)-1~3 with different molecular weight, were prepared by the conversion of poly[N-α-methacrylamide-N-ε-t-butoxycarbonyl-L-lysin-t-butyl ester (BLMA)-b-dimethylsiloxane (DMS)] which were obtained from the radical polymerrization of BLMA initiated with an azo-initiator having poly-dimethylsiloxane chains (azo-PDMS) in the presence of 2-mercaptoethanol as a chain-transfer agent. From scanning probe microscope (SPM) measurements, poly(LysMA-b-DMS) showed microphase-separated structures. The self-organization of poly(LysMA-b-DMS) was analyzed by fluorescence and 1H NMR measurements. The critical micelle concentrations (CMC) were=500~2000 mg L-1. The micelle had diameters from 221 to 274 nm. The blood compatibility of poly(LysMA-b-DMS) was evaluated from the maximum velocity of hydrolysis (Vmax) for the enzymatic reaction of thrombin and a synthetic substrate S-2238 in the presence of poly(LysMA-b-DMS). Vmax was 1.82×10-2~1.95×10-2 mM min-1. The maximum rate of conversion of plasminogen to plasmin by tissue plasminogen activator (t-PA) in the presence of poly(LysMA-b-DMS) using S-2251 was faster than the case of absence of poly(LysMA-b-DMS).
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Masahiro TANIDA, Yasuhiro KAWAGUCHI, Hiroshi KAKE, Tsutomu OISHI2008 Volume 65 Issue 2 Pages 157-163
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSThe important point to mold a heat swelling microcapsule is to disperse uniformly without destroying a micro-balloon in the molded article. Accordingly the optimization of the steam pressure of the foaming reagent, the diffusion to the shell polymer, the heat-resistance of the shell polymer and character of gas barrier for is required. According to the technique of the multivariate analysis, the statistical model was designed and constructed for the foaming start temperature (Ts) and the maximum foaming temperature (Tmax), using the raw material value of the microcapsule which has core/shell structure, grain diameter distribution and for the stirring conditions. The faction to influence the Ts and Tmax could be specified by use of the statistical model. The core/shell constitution lowering the diffusion coefficient was applied to statistic models. It was necessary to use the increase of core weight, the cross-linking agent with low functional group in the presence of sodium hydroxide, simultaneously, and a narrow size distribution of the polymer in order to form the polymer at high temperature. In addition to, rotation number under polymerization conditions was found to influence the forming character.
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Kohshiroh MIZUNO, Takehiko YAMASHITA, Yusuke WATANABE, Tomonaga UENO, ...2008 Volume 65 Issue 2 Pages 164-170
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSThe mutual relation between flame positions during vertical combustion test and thermal degradation of polyethylene (PE), polypropyl- ene (PP) and polybutene (PB) as polyolefin, and polystyrene (PS) were studied. The flame developed downward for PE and upward for PS. The flames of PP and PB remained in the middle. Notable scission products in the regions of lower molecular weight were observed for the PE thermal degradation but the major products had a higher molecular weight for all samples. On the other hand, the PS monomer accounted for 73 mol% of degradation products and 54% calculated from combustion heat. The position of the flames clearly depended on the combustion heat weighted average boiling point (CHWABP). The upper average position was proportional to CHWABP and the lower average positions of PE and PS were clearly different. The fire safety of polymeric materials is closely related to the position of the flames, and the investigation of the thermal degradation profiles of polymers will contribute to the fire safety design of industrial goods and houses.
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Kohshiroh MIZUNO, Takehiko YAMASHITA, Yusuke WATANABE, Tomonaga UENO, ...2008 Volume 65 Issue 2 Pages 171-177
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSThe effect of the molecular weight of polymeric materials on combustion was examined by using paraffin and polyethylene (PE) as examples. From the result of the vertical firing experiments of such saturated hydrocarbons with greatly differing molecular weight we found that there is a region of molecular weights that do not support combustion because volatile gas components are hardly generated. This region ranges from 240 g/mol of the paraffin to about a 35000 g/mol, we found that PE of a Mw of about 35000 can exist as a liquid within a relatively wide temperature range from the melting point of 130°C to 400°C, which is the temperature where decomposition begins: it burns while melting. The viscosity of PE has a low temperature dependence and a high molecular weight dependence, so when the Mw exceeds 50000 the surface temperature, reaches 530°C, and PE thermally degradates violently and burns as it melts. These results suggest that there is a possibility that by controlling the molecular weight, the combustibility can also be controlled.
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Tamotsu HASHIMOTO, Kurayoshi MISAWA, Michio URUSHISAKI2008 Volume 65 Issue 2 Pages 178-184
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSHydroxy-terminated telechelic polyacetals (PHBVE) were synthesized by polyaddition of 4-hydroxybutyl vinyl ether (HBVE; CH2=CH-O-CH2CH2CH2CH2-OH) in the presence of 1,4-butanediol (BD) with an acid catalyst in tetrahydrofuran (THF) at 0°C. Polyurethane elastomers with polyacetal soft segments (PHBVE-PU) were synthesized by the reaction of PHBVE with an excess amount of 4,4′-diphenylmethane diisocyanate and the subsequent chain-extension reaction with BD. PHBVE-PUs exhibited low glass transition temperature, high thermal stability, and good elastomeric properties. The effects of the Mn of polyacetal prepolymer on the thermal and mechanical properties of PHBVE-PUs were investigated. PHBVE-PU underwent smooth degradation with the treatment of aqueous HCl in THF at room temperature to give BD and urethane hard-segment residues as degradation products.
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Notes
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Junichi KAMEDA, Yasuhiro SHIBATA, Hiroaki KOUZAI2008 Volume 65 Issue 2 Pages 185-187
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSWe have investigated the oxidation decomposition of vulcanized rubber using hydrogen peroxide (H2O2)/carboxylic acids such as formic acid (HCOOH), acetic acid, acetic acid anhydride and propanoic acid. The optimum conditions were H2O2 5.0 mL, HCOOH 10 mL, 60°C, and 6 hours against a 0.5 g sample. Suitable results were obtained for residue portions of 0.15 g and product portions of 0.25 g. The product portion was found to be soluble in DMF or DMSO.
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Kazuhide KURATANI, Satoshi HASEGAWA, Takanobu KATSUMATA, Hiroaki KOUZA ...2008 Volume 65 Issue 2 Pages 188-191
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSLiquid crystalline poly(phosphate ester)s were synthesized by polycondensation of bis(2-hydroxyethyl)terephthalate and 4-[6-(ω-biphenyl-4-yloxy)-hexyl]-phenyloxy-phosphorodichloridate. The polymers were obtained with high yield, i.e., 49-57%. The molecular weights of the polymers were Mn=14300, Mw=16500, Mw/Mn=1.15. The liquid crystallinity of these polymers was studied by differential scanning calorimety, polarizing optical photomicrography, and X-ray diffractometry. It was found that most of the polymers had enantiotropic liquid crystallinity having a smectic phase.
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Hiroki ARAI, Hiroshi AWANO, Tatsuhiro TAKAHASHI, Koichiro YONETAKE, Os ...2008 Volume 65 Issue 2 Pages 192-195
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSTo improve interfacial adhesion between multi-walled carbon nanotubes (MWCNT) and polymers, the quantitative analysis of MWCNT and its chemical modifications becomes important. MWCNTs are mainly categorized into two structures. One is a tubular type, and many layers of graphite sheets are rolled; this type is commercially available as VGCF®. The other is a cup-stacked type, and six-membered rings arranged like cups are stacked up, this type is commercially available as Carbere®. In this study, the quantitative surface analysis for the two MWCNTs, which are already graphitized (no residual of metal catalyst), by neutralization titration was carried out. COOH groups are introduced by using the Friedel-Crafts reaction on the defect parts of the two MWCNTs. The introduced amounts of carboxyl groups were determined by neutralization titration. The results suggested that about 17 carboxyl groups per 100 carbons on VGCF® surface, and about 22 carboxyl groups on Carbere® were introduced, respectively.
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Kenjiro ONIMURA, Masayuki KAWASHIMA, Kazuhiro YAMABUKI, Yukio ISOBE, T ...2008 Volume 65 Issue 2 Pages 196-198
Published: 2008
Released on J-STAGE: February 22, 2008
JOURNAL FREE ACCESSα,ω-Dimesyl-terminated poly(ethylene glycol) (PEG-Ms2) and α,ω-ditosyl-terminated PEG (PEG-Ts2) were prepared from PEG (PEG1000; Mn=1000 and PEG4000; Mn=4000) and methanesulfonyl chloride or p-toluenesulfonyl chloride. α,ω-Ditosyl-terminated PEG4000 pseudorotaxane (PEG4000-TS2-pseudorotaxa-α-cyclodextrin (α-CD) was prepared from PEG4000-TS2 and α-CD in H2O. (S)-(-)-1,1′-Bi(2-naphthol) ((S)-BINOL) was added to the pseudorotaxanes in the presence of sodium hydride to give PEG-rotaxa-α-CDs end-capping (S)-BINOL (PEG-BINOL2-rotaxa-α-CD). The purified PEG4000-BINOL2-rotaxa-α-CD was isolated in 38% yield. For a PEG4000-TS2, the average number of α-CD's per chain is 29, which corresponds to 64% coverage. After end-capping reaction, the average number of α-CD's per chain is 14, which corresponds to 31% coverage. The threading level in the polyrotaxane is limited by the coverage of the polypseudorotaxane and by the competition between the end blocking reaction and dethreading. In DMF a rapid dethreading occurs.
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