Enzymatic oxidative polymerization of 2,6-dimethylphenol has been
carried out in an
aqueous organic solvent at room temperature under air. Laccase
derived from Pycnoporus coccineous
and horseradish and soybean peroxidases were active for the
polymerization, yielding polymeric materials
with molecular weights of several thousands. The product polymer
was in all cases soluble in common
organic solvents. The polymerization behavior was dependent on the
enzyme type. The effects of the
solvent composition have been systematically investigated with respect
to the polymer yield and molecular
weight. The mixing ratio between the organic solvent and buffer
affected the polymer yield, and the
highest yield was achieved in 60% buffer. Various water-miscible
organic solvents such as acetone,
methanol, and 1,4-dioxane were available as components of the mixed
solvent. In using laccase catalyst,
the acidic buffer afforded the polymer in high yields. NMR and
matrix-assisted laser desorption/ionization
time of flight mass spectroscopic analyses showed that the present
polymer was exclusively composed of
2,6-dimethyl-1,4-oxyphenylene units.
Cardanol, a major component obtained by thermal treatment of cashew nut shell liquid, is a phenol derivative mainly having a C15 unsaturated hydrocarbon chain with 1–3 double bonds at the m‐position. We polymerized cardanol using an Fe‐salen complex as the catalyst to give a soluble polyphenol containing the unsaturated alkyl group in the side chain. The polymer was subjected to hardening by a cobalt naphthenate catalyst or thermal treatment, yielding crosslinked film with high gloss surface.
: Enzymatic oxidative polymerization of 4-hydroxybenzoic acid derivatives using oxidoreductases has been carried out in an aqueous organic solvent at room temperature under air. The monomers used in this study were 4-hydroxybenzoic acid, 3,5-dimethoxy-4-hydroxybenzoic acid (syringic acid) and 3,5-dimethyl-4-hydroxybenzoic acid. The latter two monomers were subjected to oxidative polymerization using horseradish peroxidase (HRP), which involved elimination of carbon dioxide and hydrogen from the monomer to produce poly(1,4-oxyphenylene). Oxidoreductases, soybean and Coprinus cinerius peroxidases, Pycnoporus coccineus and Myceliophthore laccases, were active for the polymerization and the enzyme type and its origin greatly a †ected the polymerization behaviour. The e †ects of solvent composition have been systematically investigated with respect to polymer yield and molecular weight. In the case of HRP-catalysed polymerization of syringic acid, the highest molecular weight (1É5 ] 104) was achieved in acetone/phosphate bu †er (pH 7) (40 : 60 vol%). NMR, IR and matrix-assisted laser desorption/ionizationÈtime of Ñight mass spectroscopic analyses of the polymer showed that the present polymer consisted made exclusively of 1,4-oxyphenylene unit and that the terminal structure was a carboxylic acid group at one end and a phenolic hydroxyl group at the other.of Chemical Industry ( 1998 Society Polym. Int. 47, 295È301 (1998)
A new concept for the design and laccase-catalyzed preparation of "artificial urushi" from new urushiol analogues is described. The curing proceeded under mild reaction conditions to produce the very hard cross-linked film (artificial urushi) with a high gloss surface. A new cross-linkable polyphenol was synthesized by oxidative polymerization of cardanol, a phenol derivative from cashew-nut-shell liquid, by enzyme-related catalysts. The polyphenol was readily cured to produce the film (also artificial urushi) showing excellent dynamic viscoelasticity.
For friction stir welding (FSW) of advanced high strength steel (AHSS) sheets with tensile strength grades between 590 and 1180 N mm 22 , the appropriate welding condition range and the influence of welding conditions on microstructures and mechanical properties of the welds were investigated. The appropriate welding conditions to avoid defects such as the incomplete consolidation at the bottom of the weld were obtained for the steel sheets up to 1180 N mm 22 grade. The higher tool rotation speed evidently resulted in the larger volume fraction of martensite and higher hardness in the stir zone (SZ), attributed to an increase in the peak temperature of its thermal cycle. The tensile strength of the weld joint was as high as that of the base metal for the steels up to 980 N mm 22 grade, but slightly lower than that of the base metal for the steel of 1180 N mm 22 grade due to the heat affected zone (HAZ) softening.
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