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Volume 45, Issue 6
Displaying 1-12 of 12 articles from this issue
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Hajime SERITA, Manabu SENO, Katsutoshi IWAMOTO, Koichi MURAI1988 Volume 45 Issue 6 Pages 457-462
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSPoly (N-alkyl-2-vinylpyridinium salts) were prepared by the reaction of poly (2-vinylpyridine) with alkyl bromides. The flocculation of kaolin by the polyelectrolytes was investigated by means of i) the measurements of heat of adsorption, and ii) the adsorption of polyelectrolytes onto kalin particles. Results obtained are as follows. 1) The heat of adsorption was exothermic. 2) The amounts of adsorption (the saturated values of adsorption) and the heats of adsorption increased with increasing temperature. 3) The optimum concentrations of polyelectrolytes required to flocculate 0.5g of kaolin were 10-20ppm in a range of pH2-10, the suspensions of kaolin were stable at less than pH2 or more than pH10.4) There was no relationship between the adsorption amounts and the degree of quaternization at a range of 25-53%. 5) These results were well explained by the model of the loop-train-tail type adsorbed conformation.View full abstractDownload PDF (1137K) -
Shunichi NUMATA, Nobuo SHIBATA, Masatugu OGATA, Hiroshi HOZOJI, Hirosh ...1988 Volume 45 Issue 6 Pages 463-471
Published: June 25, 1988
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSEffects of various flexibilizers on viscoelastic properties and on the ductilization mechanism were investigated for anhydride-cured epoxy resins. Rubber particle dispersion type flexibilizers lower the moduli of epoxy resins in the glass state, but cause hardly any drops in the glass transition temperature (Tg). By contrast, compatible flexibilizers lower moduli very little, except those including γ-dispersion or spreading α-dispersion due to the glass transition, while they lower the Tgs significantly. These results indicate that the rubber-modified type flexibilizers are the most appropriate to lower the modulus in the glass state without lowering Tg.View full abstractDownload PDF (1175K) -
Shunichi NUMATA, Nobuo SHIBATA, Masatugu OGATA, Hiroshi HOZOJI, Hirosh ...1988 Volume 45 Issue 6 Pages 473-480
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSEffects of various flexibilizers on mechanical destruction properties of epoxy resins and relationships between viscoelastic properties and destruction properties were investigated. When a γ-dispersion of epoxy resin or α-dispersion due to rubber particles appears the low temperature region, moduli decreased, and elongation increased in the glass state. When plastic deformaion such as necking took place, impact strength increased. The higher the magnitude of α-dispersion due to rubber particles and γ-dispersion of epoxy resin, the higher the impact strength was.View full abstractDownload PDF (1145K) -
Shinya NAKAJIMA, Noboru YAMAZAKI, Kimio KURITA, Eiichi WADA1988 Volume 45 Issue 6 Pages 481-484
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSTo study the effects of whiskers on reinforcement of dental restorative resin, the mechanical breaking strengths and proportional limits were measured by means of compressive, tensile, and bending tests for composites composed of (1) a copolymer of 2, 2-bis [4- (3-methacryloxy-2-hydroxypropoxyl) phenyl] propane and triethylene glycol dimethacrylate and (2) silicon nitride (Si3N4) or potassium titanate (K2O·6TiO2 or K2O·6TiO2·1/2H2O) whiskers or the same whiskers treated with γ-methacryloxy propyl trimethoxysilane (I), γ-amino propyl triethoxysilane (II), or γ-glycidoxy propyltrimethoxysilane (III). In the case of I, the two mechanical values of the composites containing the treated whiskers were greater than those of the composites containing nontreated whiskers at every volume fraction of the whiskers, while in the cases of II and III the observed treating effects were within experimental error of the values for K2O·6TiO2 whiskers. With increasing mean axial ratio of the whiskers, the values of the proportional limits increased for all the composites containing either nontreated whiskers or those treated with I.View full abstractDownload PDF (1077K) -
Kunihiko TAKEDA, Minoru AKIYAMA, Takafumi YAMAMIZU1988 Volume 45 Issue 6 Pages 485-490
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSFrom copolymerization of styrene (M1) with p-formylstyrene (M2), monomer reactivity ratios were determined to be r1=0.16 and r2=1.43. Q and e values of p-formylstyrene were calculated to be 2.36 and 0.41, respectively, from the ratios. Crosslinked polymers were prepared by copolymerization of formylstyrene with divinylbenzene. When each monomer used is a mixture of meta and para isomers, the density of crosslinks varied greatly with progress of polymerization. In contrast, in the copolymerization of p-formylstyrene with m-divinylbenzene, the density of crosslinks was found nearly constant all the time during polymerization. Stepwise calculations of the copolymer composition were performed using the above data, and the most appropriate set of Q and e values of m-divinylbenzene could be chosen among several sets so far reported.View full abstractDownload PDF (1142K) -
Takashi YOKOYAMA, Toru KOYAMA, Noriyuki KINJO, Toshikazu NARAHARA1988 Volume 45 Issue 6 Pages 491-498
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSIsocyanurate-oxazolidone resins were prepared from 2, 4-tolylene diisocyanate (TDI) and 2, 2-bis [p- (2, 3-epoxypropyloxy) phenyl] propane (BPAGE) using N-methylmorpholine as a catalyst. Model polymers containing isocyanurate, oxazolidone, and uretidindione rings were prepared from TDI, diphenylmethane diisocyanate (MDI), triphenyl isocyanurate and BPAGE in order to form calibration curves for infrared spectrum. Composition of hetero rings in the cured product varied with curing temperature, time, and compound ratio. Isocyanate groups changed mainly to isocynanurate rings with ca. 20 mol% of the groups becoming oxazolidone rings. Product contents of uretidindione rings were less than 6mol%. Reaction routes were analyzed from conversion ratios. Variations in the bending strength of the resins made from modified MDI and BPAGE are discussed from product contents of hetero rings.View full abstractDownload PDF (1176K) -
Jiro SAKATA, Minoru YAMAMOTO, Masana HIRAI1988 Volume 45 Issue 6 Pages 499-503
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSHexamethyldisiloxane (M2) and octamethylcyclotetrasiloxane (D4) were used as monomers, and plasma polymerized films were deposited on porous substrates under various polymerization conditions (with changing sample positions, monomer pressure, radio frequency power, and polymerization time). Deposition rates of the plasma polymerized films and gas permeability characteristics for oxygen and nitrogen of the composite membranes were examined, in order to determine effects of polymerization conditions on gas permeability. The polymerization time required to obtain permselective membranes became shorter at the positions nearer to an RF electrode. Deposition rates of M2 increased with increasing the value of RF power/monomer pressure. In the case of D4, such relationships were not observed. When the pressure was high, the RF power determined the deposition rates of D4. When the pressure was low, the deposition rates were independent of the RF power and were determined by monomer supply. Under the condition of supplying excessive energy to monomers, drops in deposition rates and permselectivity were observed. The membranes prepared under the conditions giving high deposition rates showed high permselectivity.View full abstractDownload PDF (874K) -
Kazuta MITSUISHI, Soji KODAMA, Hitoshi KAWASAKI, Makoto TANAKA1988 Volume 45 Issue 6 Pages 505-510
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSPolypropylene (PP) /thermoplastic elastomer (TPE) blend samples filled with calcium carbonate (CaCO3) were prepared. These had been modified with mono-alkyl phosphate esters. They were tested to improve modulus and impact properties of filled composites. The relations between impact properties of composites and levels of TPE content and length of alkyl chain of modifiers have been investigated. Styrene/butadiene block copolymer (SBS) was found to be the best for the improvement of impact strength. How length of alkyl chain depended on impact strength and on void fraction incorporated by drawing at filler/polymer interface of PP/SBS composites was studied. Additions of modified CaCO3 to PP filled with 2.5-5wt% of SBS have produced major improvements not only in impact strength but also in modulus of filled composites over results with PP base resin.View full abstractDownload PDF (952K) -
Kazuhiko ABE, Morie SEKIGUCHI, Teruo OKANO, Kazunori KATAOKA, Yasuhisa ...1988 Volume 45 Issue 6 Pages 511-517
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSIn order to clarify the antithrombogenic mechanism of 2-hydroxyethyl methacrylate-styrene ABA type block copolymer which has microdomain-structured surfaces, shape and cytological changes of rat platelets adhered to the polymer surfaces in vitro were analyzed by scanning and transmission electron microscopy. Poly (2-hydroxyethyl methacrylate) and polystyrene with homogeneous surfaces were used for control polymers. Platelets which adhered to the homogeneous surfaces underwent aggregation and cytological changes such as release of alpha-granules and dense bodies as well as extensions of the open canalicular system. On the other hand, platelets which adhered to the microdomain-structured surfaces were round, and were observed to retain organella such as alpha-granules and mitochondria. The block copolymer with a lamella-shaped microdomain structure has a more significant inhibitory action on platelet activation than the copolymers with the surfaces with sea-island type and reversed sea-island type microdomains or that with the homogeneous surfaces. The antithrombogenicity of HEMA-St block copolymer may be due to the regulated effect of microdomain structure on glycoprotein assemblage of platelet plasma membranes.View full abstractDownload PDF (2642K) -
Seiichi YAMASHIRO1988 Volume 45 Issue 6 Pages 519-525
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe segmented polyurethanes obtained from polyester, 4, 4′-diphenylmethane diisocyanate and 1, 4-butanediol were dissolved in dimethylformamide and precipitated into ten fractions by adding a mixture of n-hexane and diethyl ether. The hard segment distributions were studied by means of solution viscosity, nitrogen content, and IR measurements for these fractions and also by measuring mechanical properties of elastic fibers. The ester and the urethane exchange reactions were studied by melt viscosity. The former reaction was completed in 60 min at 170°C, while the latter reaction took 400 min.View full abstractDownload PDF (1100K) -
Jiro SAKATA, Minoru YAMAMOTO, Masana HIRAI1988 Volume 45 Issue 6 Pages 527-529
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSIn order to examine the effect of monomers on the gas permeability of plasma polymerized films, five kinds of organosilicic compounds (tetramethylsilane and the derivatives substituted by ethoxy groups) were used as the monomer, and plasma polymerized films were deposited on porous substrates. The gas permeability and IR spectra were measured. It was found that each plasma-polymerized films retained the chemical structures of the associated monomers. The ratio of oxygen to nitrogen permeation rates decreased with increasing the numbers of the substituted ethoxy groups. The membrane prepared from the monomer in which two ethoxy groups were substituted showed the highest value of the oxygen permeation rate. It was found that the oxidation state of Si in the monomer is the important factor in determining the gas permeability of the plasma polymerized films.View full abstractDownload PDF (494K) -
Akio KINUGAWA, Yoshitsugu KISE1988 Volume 45 Issue 6 Pages 531-534
Published: June 25, 1988
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSA GPC method was developed to measure molecular weight distributions (MWDs) of liquid crystalline aromatic polyesters (LCPs) which can not be dissolved by ordinary organic solvents. The combination of pentafluorophenol (PFP) and polystyrene gel columns was found to give a reproducible GPC curves of LCPs at 60°C by using a temperature-controlled instrument made at our laboratory. This GPC method revealed heretofor unrecognized features of the MWDs of LCPs: LCP-A, LCP-B, LCP-C (Fiber). GPC-LALLS method was utilized to make absolute molecular weight calibration curves for LCPs.View full abstractDownload PDF (1166K)
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