NIPPON GOMU KYOKAISHI

[title in Japanese]

[in Japanese]

2004 Volume 77 Issue 8 Pages 265
Published: 2004
Released on J-STAGE: May 28, 2007

DOIhttps://doi.org/10.2324/gomu.77.265

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Effect of Supercritical CO₂ on Polymer Properties

Masahiro OHSHIMA

2004 Volume 77 Issue 8 Pages 266-271
Published: 2004
Released on J-STAGE: May 28, 2007

DOIhttps://doi.org/10.2324/gomu.77.266

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When CO₂ is dissolved into a polymer, several polymer properties are drastically changed. In this article, solubility and diffusivity of CO₂ in several molten state thermoplastics as well as some rubbers are discussed. In addition to illustrating the solubility and diffusivity data of CO₂ into polymers, the data of CO₂ induced depression of glass transition temperature as well as viscosity are introduced.

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Separation and Extraction of Functional Materials by Using Supercritical Fluids

Application to Natural Materials and Polymers

Motonobu GOTO

2004 Volume 77 Issue 8 Pages 272-277
Published: 2004
Released on J-STAGE: May 28, 2007

DOIhttps://doi.org/10.2324/gomu.77.272

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The extraction and separation of natural materials and polymers are reviewed. Functional components from plant materials are focused as natural supplements or functional food additives. Supercritical carbon dioxide has been used in extraction processes of bioactive components such as antioxidants and vitamins. Higher pressure and higher temperature process could improve the efficiency of the extraction due to the significantly enhanced solubility. Subcritical water is also promising solvent for the extraction of natural materials.
Supercritical fluids can be used for the fractionation of various polymers based on the pressure or temperature dependence of the solubility. Monomers and oligomers are extracted from polymers with supercritical fluids to purify the polymers.

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Separation of Individual Oligomer Homologs by Supercritical Fluid Chromatography and Applications of the Oligomers to Polymer Science

Koichi UTE

2004 Volume 77 Issue 8 Pages 278-281
Published: 2004
Released on J-STAGE: May 28, 2007

DOIhttps://doi.org/10.2324/gomu.77.278

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Recent progress in supercritical fluid chromatography (SFC) of oligomers and application of the individual oligomer homologs to polymer science are described. First, the feasibility of using a monolithic silica-rod column for the SFC separation of Silicone-OV17, Triton-X100, and isotactic poly(methyl methacrylate) (PMMA) was examined. The monolithic silica-rod column showed higher separation efficiency in the SFC separation of oligomer homologs than conventional columns packed with silica particles (5μm).
Second, SFC was applied to the analysis of polyprenols extracted from bark, oot, leaf, and seed coat of a rubber-producing plant, Eucommia ulmoides oliver. The analysis clearly showed that the polyprenols from bark consists entirely of poly-cis homologs while those from root and seed coat consist of poly-cis and poly-trans homologs. Both SFC and matrix-assisted laser-desorption ionization mass spectrometry analyses of long-chain polyprenols from the leaves showed good resolution of poly-trans homologs up to 100mer. Third, applications of uniform isotactic and syndiotactic PMMAs obtained by SFC fractionation to the study of molecular weight dependence of diffusion coefficients and to the study of their stereocomplex formation are briefly mentioned.

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Dyeing Technique Using Supercritical Carbon Dioxide

Kiyoshi MATSUYAMA, Kenji MISHIMA

2004 Volume 77 Issue 8 Pages 282-286
Published: 2004
Released on J-STAGE: May 28, 2007

DOIhttps://doi.org/10.2324/gomu.77.282

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The use of water and organic solvents in dyeing processes causes environmental problems. The textile industry is putting significant efforts into its social obligation to reduce the large amount of waste discharged into the environment during their dyeing process. Due to this environmental task, dyeing in supercritical carbon dioxide (SC-CO₂) has been receiving much attention as an environmentally benign procedure. The synthetic fibers, such as polyester, polypropylene(PP), polyethylene terephthalate(PET) etc., were successfully dyed by SC-CO₂ based technology. Recently several investigators have attempted to dye cellulose fibers in SC-CO₂, because of its large share on the market. They reported that the modified cottons were successfully dyed, but a very high degree of modification of fabric was required. Their results suggest that further experiments are required.
In this work, the dyeing of cellulose fibers with reactive disperse dyes was attempted using SC-CO₂ as a solvent. For pretreatment, cellulose fibers were treated with ethylene glycol derivatives. The dyeing was compared with the dyeing using other disperse dyes under the same conditions. The color yield of the fibers was assessed by K/S measurements before and after washing to investigate the quality of the dyeing in this medium. Good color intensity and wash fastness were obtained.

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Polymerizations in Supercritical Carbon Dioxide

Mitsutoshi JIKEI

2004 Volume 77 Issue 8 Pages 287-292
Published: 2004
Released on J-STAGE: May 28, 2007

DOIhttps://doi.org/10.2324/gomu.77.287

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Supercritical carbon dioxide deserves much attention as a sustainable solvent, potentially alternative to volatile organic solvents. It has been reported that numerous polymerizations can be carried out in supercritical carbon dioxide, despite of the limited solublity of polymeric materials. The article reviews the polymerizations in supercritical carbon dioxide which are classified into three categories: 1) chain-growth polymerizations; 2) step-growth polymerizations; 3) copolymerizations with carbon dioxide in supercritical carbon dioxide. It turned out that many radical polymerizations can be carried out in supercritical carbon dioxide with or without surfactants. Melt-polycondensations are also applicable in supercritical carbon dioxide. Carbon dioxide plays a role not only as a solvent but also as a reactive monomer in some polymerization reactions.

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Development of Supercritical Water Processes into Chemical Recycling of Synthetic Polymers or Conversion of Biomass into Chemical Raw Materials

Kiyohiko Tajima, Toshiyuki Nonaka, Kunio Arai

2004 Volume 77 Issue 8 Pages 293-298
Published: 2004
Released on J-STAGE: May 28, 2007

DOIhttps://doi.org/10.2324/gomu.77.293

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The chemical industry based on petrochemistry has faced resource problems and environmental problems. And also the disposal of synthetic polymers that have been produced, used and scrapped in large scales for many years has become an important problem to clean up the earth environment. Recently the chemical recycling of synthetic polymers and the utilization of biomass as chemical raw materials have been studied in order to solve these problems. On the other hands the utilization of sub- and supercritical water is attracting increased attention as a medium for organic chemistry. This review is organized around the chemical recycling of synthetic polymers or the conversion of biomass to chemical raw materials using sub- and supercritical water as a reaction medium.

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[title in Japanese]

[in Japanese]

2004 Volume 77 Issue 8 Pages 299-300
Published: 2004
Released on J-STAGE: May 28, 2007

DOIhttps://doi.org/10.2324/gomu.77.299

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