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Volume 62, Issue 6
Displaying 1-9 of 9 articles from this issue
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Through a Business Development of Polylactic Acid, LACEA®Nobuyuki KAWASHIMA, Mitsunori MATSUO, Masahiro SUGI2005 Volume 62 Issue 6 Pages 233-241
Published: June 25, 2005
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSPolymers derived from plants, such as polylactic acid (PLA), are among the materials that contribute to the curbing of the increase in greenhouse gases and the saving of fossil resources. PLA is finding an increasing number of applications for packaging and containers, agricultural and civil engineering and composting. In recent years, efforts are being made to apply PLA to durable goods such as parts for electrical appliances and automotives. A study is being conducted about how to express the content of the plant-derived ingredients contained in plastics or products in terms of the bio-based content as a measure for assessing a reduction in the environmental burden. A switchover from petroleum-based polymers to bio-based polymers will be accelerated through the resolution of the following issues: 1) improvement of physical properties, 2) definition and spread of the concept of bio-based polymers and 3) collaboration with the government and regulatory authorities for the achievement of the targets set in the Kyoto Protocol.View full abstractDownload PDF (4699K) -
Masaki KOJIMA, Yuko IKEDA2005 Volume 62 Issue 6 Pages 242-250
Published: June 25, 2005
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSAn environmental-friendly chemical recycling process in supercritical carbon dioxide was established for sulfur-cured natural rubber vulcanizates. Diphenyl disulfide was found to be effective as a devulcanizing reagent for this process. The presence of fillers such as carbon black and silica did not prevent the devulcanization reaction. Not only natural rubber but also synthetic rubbers could be subjected to this chemical recycling. The tensile properties of recycled rubber vulcanizates made from virgin rubber and 20-60 phr of recycled rubber were over 90% of those of the original vulcanizates. The devulcanizing reagent was found to be selectively absorbed in the sulfur-cured vulcanizates, which led to the highly efficient devulcanization reaction. This method will be useful for recycling of other conventional sulfur-cured rubber vulcanizates.View full abstractDownload PDF (1917K) -
Takashi SAWAGUCHI, Yoshio MUROGA, Hideaki ISHIKAWA, Toru HOSHI, Toshik ...2005 Volume 62 Issue 6 Pages 251-260
Published: June 25, 2005
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSBlends of syndiotactic polystyrene (sPS) with poly (methyl methacrylate) (PMMA) are usually immiscible and have phase-separated morphology. In this study, nanocomposites of sPS with PMMA were successfully prepared by a newer method using supercritical carbon dioxide fluid (scCO2). Methyl methacrylate monomer was impregnated into the amorphous phases of sPS and was polymerized in situ in scCO2. PMMA may be dispersed in the amorphous phase of sPS at the molecular level. The formed nano-structure is relatively stable at first, but phase separation occurred by heating above melting temperature of the α crystallite of sPS. In the blend prepared in scCO2, the glass transition temperature at 100°C and the crystalline transformation temperature of sPS at 190°C decreased with increasing mass of PMMA. These results were discussed based on a molecular dispersion with the entanglement of sPS amorphous molecules with PMMA molecules.View full abstractDownload PDF (3501K) -
Kazuhiko INOUE, Midori YAMASHIRO, Masatoshi IJI2005 Volume 62 Issue 6 Pages 261-267
Published: June 25, 2005
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSWe describe an intelligent biomass-plastic with a rewritable shape memory. First, we synthesized the network structure by cross-linking a polylactic acid (PLA) derivative with a diisocyanate linker. This structure performed much better as a shape memory than the inherent crystal domain. Then, we introduced the furan and maleimide functional groups, which form a thermo-reversible bonding based on Diels-Alder reaction, into the molecular structure of the PLA derivative. This bond works like a thermo-switch, providing two normally incompatible characteristics, namely shape memory and recyclability (rewritability). Currently, shape-memory plastics with cross-linked structures are not rewritable. When the thermo-switch is on at low temperatures, the bio-plastic ‘memorizes’ its original shape and can completely recover from a deformed shape. When the switch is turned off at high temperatures, the memory is erased and the plastic becomes rewritable.View full abstractDownload PDF (2627K) -
Hideki NAKAYA, Hisayuki KOBAYASHI, Yuji IMAHORI, Mitsuo TSUKAMOTO, Hid ...2005 Volume 62 Issue 6 Pages 268-274
Published: June 25, 2005
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSLow molecular weight components such as oligomer in fluoropolymers could be efficiently extracted with supercritical CO2 by the addition of water. The CO2 density, amount of CO2, and initial water concentration influenced the extraction process. Oligomers were efficiently extracted over the critical density of CO2. Under the best conditions with scCO2, MW/Mn of polymer afterextraction decreased from 1.86 to 1.16. that is to say. a sharp molecular weight distribution polymer was obtained. Successful extraction of oligomers was also achieved when supercritical fluoroform (R23) and supercritical perfluoroethane (R116) were individually substituted for scCO2. However, the amounts of the molecular weight components with scCO2 were larger than the amounts with scR23 and scR116.View full abstractDownload PDF (1398K) -
Takeshi SAKO, Ryotaro SAHASHI, Yoshihiro FUJITA2005 Volume 62 Issue 6 Pages 275-282
Published: June 25, 2005
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSSupercritical carbon dioxide was reacted with 2-methyloxirane in the presence of LiBr catalyst in a continuous tank reactor to produce a cyclic carbonate, i. e., 4-methyl-1, 3-dioxolan-2-one. High conversion (>70%) and high product selectivity (>90%) were achieved when the reaction was carried out for 30 min at 80-90°C and 15-20 MPa. The reaction rate constants of main and side reactions were determined from the experimental data and their dependence on the temperature, pressure, and amount of catalyst was analyzed in detail. The selective separation of cyclic carbonate from the supercritical mixture was also investigated. When the temperature and pressure of the supercritical mixture flowing out of the reactor were lowered from 80-90°C and 15-20 MPa to 35-40°C and 4-6 MPa, 4-methyl-1, 3-dioxolan-2-one with a purity of more than 90% was obtained with a recovery rate higher than 70%.View full abstractDownload PDF (1723K) -
Mitsuru AOYAGI, Masamitsu FUNAOKA2005 Volume 62 Issue 6 Pages 283-290
Published: June 25, 2005
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSRecyclable lignin-based polymeric materials (lignophenol; LP) have been synthesized directly from native lignin using a phase-separation system composed of phenols and concentrated acid. The photochemical behaviors of LP were studied by UV-vis spectroscopy, fluorescence spectroscopy and FT-IR. The results of UV-vis and second derivative UV-vis spectra showed a particular absorbance for each LP in the visible region. Several fluorescence emissions of LP were observed at 400-600 nm using various excitation wavelengths. LP absorbed visible light by hydrogen bonds between conjugations and hydroxyl groups. Photo-electricity conversion devices of nano-porous titanium dioxide sensitized with LP have showed stable visible light conversion under visible light irradiation. Moreover, stable cation radicals on LP were produced repeatedly, as confirmed by cyclic voltammetry. The best performance under a 150-W Xe lamp with a L41 UV cut filter was 0.48 V, 4.3 mA cm-2, ff=0.54 and η=0.8% (2nd derivative-I of Hinoki-ligno-p-cresol). As LPs include a lot of hydroxyl groups and 1, 1-bis (aryl) propanyl structures, both complexes and interactions were produced between LP and TiO2. These interactions acted as injection routes to TiO2 of electron transfers from LP in excited states. Performances of these photo-electricity conversion devices were reflected in grafted phenols in LP. In conclusion, LP-nano porous TiO2 electrodes will be developed for photo-electricity conversion devices produced by forest carbon resources.View full abstractDownload PDF (1736K) -
Mikiko HIROSE, Makoto TAKAHASHI, Kenichi MORI, Kenji OGINO2005 Volume 62 Issue 6 Pages 291-296
Published: June 25, 2005
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSCrosslinked porous polymers were synthesized utilizing supercritical CO2 as a diluent in a stainless steel column, using styrene (St) or methyl methacryrate (MMA) as a monomer and divinylbenzene (DVB) or ethylene dimethacryrate (EDMA) as a crosslinking agent. The polymerizations were carried out at a monomer concentration in the range from 30 to 60vol% relative to the total column volume under a pressure of 10-25MPa for 2-10 hours. The pore characteristics and the homogeneity of fabricated monolithic columns were evaluated from the elution behaviors of toluene and polystyrene standards using tetrahydrofuran as an eluent. In St-DVB systems, the monolithic column showing the high selectivity for the size exclusion separation was obtained by adjusting the polymerization conditions. In MMA-EDMA systems, it was difficult to obtain the monolithic column with the pores for the size exclusion separation, but sufficient homogeneous packing was observed. The addition of CO2-philic 2, 2, 3, 3, 4, 4, 4-heptafluoro butyl methacrylate decreased the size of particles, and increased the theoretical plate number of the column. The pores, which are necessary for the size exclusion separation, were formed by twostep polymerization in which the polymerization temperature varied from 70°C to 100°C.View full abstractDownload PDF (1789K) -
Kosuke TOMITA, Hiroyuki SHIRAHAMA, Tomohiro NAKAJIMA, Ayumi UENO2005 Volume 62 Issue 6 Pages 297-300
Published: June 25, 2005
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSCopolyesters of L-lactide (LA) were synthesized from LA and caprolactone (CL) or 4-t-butylcaprolactone (48CL). Their biodegradability against a thermophile capable of degrading poly (L-lactide) was investigated. The strain grew in a medium containing copolyesters, accompanied by decreases in their residual weight and molecular weight and an increase in their enthalpies of fusion, which showed the progress of their biodegradation. The copolymer including 4BCL was suggested to be superior in biodegradability to that of copolymer including CL, contrary to the former's inertia to such an enzyme as proteinase K.View full abstractDownload PDF (763K)
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