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Volume 43, Issue 8
Displaying 1-10 of 10 articles from this issue
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Yukio OKADA, Yasuhiko OONO1986 Volume 43 Issue 8 Pages 459-463
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThiocarboxylic acids (S-acid: SA), such as thioacetic acid (TAc) and thiobenzoic acid (TBz), initated the thermal polymerization of methyl methacrylate (MMA). Those results were highly in contrast with the functions of most of the compounds having SH-groups as terminators of propagation. The overall activation energies for polymerization were caluculated to be 11.9 kcal/mol (for TAc system) and 9.8 kcal/mol (for TBz system), respectively. From the kinetic data, the following rate equation was obtained.
Rp=k [MMA] [SA]
The composition curve of the copolymerization of MMA and styrene initiated by SA indicated that the polymerization proceeded via a radical mechanism. The chain transfer constants to SA's were approximately 0.26 (for TAc) and 0.26 (for TBz) at 60°C, respectively.View full abstractDownload PDF (779K) -
Kenichiro SUETSUGU, Tadashi SAKAIRI1986 Volume 43 Issue 8 Pages 465-469
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSA method which can predict the processing conditions needed to get a required flexural modulus has been examined using the modified Halpin-Tsai equation reported in the previous paper. The relation of the modified Halpin-Tsai equation to processing factors such as the mixing speed (v) and the mixing time (t) is derived. The relations between the average aspect ratio (x) and the mixing speed (v), or the mixing time (t) for a glass short-fiber-reinforced polycarbonate have been investigated. These are discussed along with the experimental results for other composite materials. When (t) is fixed (t=t1), the logarithm of x is directly proportional to the logarithm of v in the range of mixing speed from 20rpm to 100rpm. The slope of lines is almost constant around the time t1. Secondly, when (v) was fixed (v=vk), the logarithm of x becomes directly proportional to that of t within a few minutes. The change of v near vk makes little difference to the slopes. An approximate equation x (t, v) as a function of mixing time t and speed v has been derived. Comparing the above equation x (t, v) with x in the modified Halpin-Tsai equation, the processing conditions of v and t needed in order to produce composite materials having desirable flexural moduli can be predicted without repeating experiments on a injection molding.View full abstractDownload PDF (844K) -
Hideki FUJIWARA, Kunio GOTO1986 Volume 43 Issue 8 Pages 471-479
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSDispersion forms of poly (vinyl chloride) -polystyrene blends were studied. Samples were prepared by using open two rolls in air at 170°C. In these systems, given polymers were found to be incompatible with each other. Vinyl chloride-b-styrene copolymers were shown to be effective in coordinating these homopolymers: the dispersion form as well as thermostability of the blends were improved.View full abstractDownload PDF (2490K) -
Takashi IGARASHI, Shingo KONDO, Mitsuhiro MASUYAMA, Seiichiro TAMAYOSH ...1986 Volume 43 Issue 8 Pages 481-488
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThere are two different stages in the peeling of specimens bonded with rubbery adhesive layer. First, peeling starts with production of an initial crack, then the peeling continues with the crack propagation if external force is exerted. Each process obeys different mechanical laws. This study found that there is a transient stage connecting the two stages during it the initial crack propagates spontaneously. The spontaneously propagating crack was observed by high-speed camera. Converting elastic energy of elongated adhesive layer into surface energy, the crack extends. The effect of energy dissipation occurring around the crack tip was discussed using a mechanical model, and the results were compared with the experimental data. Distance of crack propagation was shortened according to an exponential function of the energy dissipation.View full abstractDownload PDF (1570K) -
Tsuguo KOBAYASHI, Hideki ASANO1986 Volume 43 Issue 8 Pages 489-497
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESS(1) The variation of creep compliance with time was greatly affected by loading stress and temperature. Above a critical stress the creep compliance changed from linear to non-linear on the semilogarithmic scale within a loading period of 100h. (2) The creep compliance of polypropylene filled with talc or glass fibers decreased, and the maximum critical stress for linear creep deformation increased with their content. (3) The glass fibers were most effective in raising the critical stress, the glass fibers mixed with talcs were the next and talcs were the least effective. (4) The maximum critical stress for linear creep deformation of polypropylene filled talc (10-30 wt%) increased by about 10-60%, and that filled with glass fiber (10-30 wt%) increased by about 30-100% in comparison with that of non-filled polypropylene.View full abstractDownload PDF (966K) -
Katsuhiko NAKAMAE, Takashi NISHINO, Yukio SHIMIZU, Katsuhiko HATA, Tsu ...1986 Volume 43 Issue 8 Pages 499-506
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe temperature dependence of the elastic modulus El of crystalline regions of poly (p-phenylene terephthalamide) (PPTA) in the direction parallel to the chain axis has been investigated by X-ray diffraction. At room temperature, the value of El for the (002), (004), and (006) planes of PPTA was 156 GPa. However, the value of El began to decrease near 150°C, and it became 119 GPa at 348°C. The thermal expansion coefficient a of the crystallites in the direction parallel to the chain axis changed discontinuously at about 150°C (<150°C; α=-1.4×10-6K-1, > 150°C; α= -4.0×10-6K-1). Also, the thermal expansion coefficient of the crystallites in the direction perpendicular to the chain axis changed discontinuously at about 150°C. These phenomena and the results of dynamic mechanical measurements show that the mobility of chain molecules in the crystalline regions, i. e., incoherent thermal vibration of crystal lattice, increases beyond 150°C, and that this causes the decrement of El, at high temperature. The physical properties, especially the large deformation region, of the specimen were directly controlled by the decrease of El, at high temperature.View full abstractDownload PDF (1759K) -
Ken-ichi NAKAZATO, Kiichi SUZUKI1986 Volume 43 Issue 8 Pages 507-513
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSSolutions of acrylamide (AAm), N, N′-methylenebisacrylamide (MBAA) and N-dimethylaminopropylmethacrylamide (DMAPMA) in a water-ethanol mixture were suspended in liquid petroleum hydrocarbon and were copolymerized to give spherical hydrophilic gel particles. The cumulative distribution curves of pore diameter of the gels were obtained by eluting water soluble materials, such as ethylene glycol oligomers and poly (ethylene oxide), through a column packed with the gels. With increasing amount of crosslinking agent, MBAA, in the monomer feed from 10.0 to 20.0 mol%, the exclusion limits of the gels decreased from 1.0×105 to 1.1 ×103. At a fixed amount (13.3 mol%) of MBAA in the monomer feed, the exclusion limits decreased from 5.5×104 to 4.7×103 with increase in the molar ratio of DMAPMA to AAm from 0.010 to 0.249.View full abstractDownload PDF (1097K) -
Hiroshi NARUKAWA, Shuji KAWAI, Haruo NAKAYASU1986 Volume 43 Issue 8 Pages 515-519
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSViscosities of unsaturated polyesters whose molecular weights varied over the range for commercial resins were measured with capillary- and pipette-type viscometers at different temperatures. The slope of the logarithmic plot of viscosity vs. molecular weight was smaller than 3.4 but larger than 1.0. The empirical relationship shows that the molecular weights of the samples are smaller than the critical molecular weight; hence chain entanglement can not occur during flow. Viscosities of the unsaturated polyesters containing phthalic acid were higher than those of the polyesters containing only maleic acid. Other factors affecting viscosity are discussed according some empirical relations.View full abstractDownload PDF (761K) -
Myung Whan HWANG, Shigeru YAMAMOTO1986 Volume 43 Issue 8 Pages 521-528
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSDeterioration induced by partial discharge was investigated for low-density polyethylene samples. Under an electrical field, a cold-drawn PE film was stretched perpendicularly to the direction of the original drawing. The starting voltage of the discharge shows a minimum at the draw ratio of 1.2 to 1.8. Around the same draw ratio, the elastic modulus and mechanical loss factor (tan δ) of the sample exhibit a minimum and a maximum, respectively. According to the X-ray analysis, the size of microcrystals decreases with increasing draw ratios. Reorientation of the molecular chains was observed above a draw ratio of 1.5 by the IR method.View full abstractDownload PDF (1357K) -
Kiichi HASEGAWA, Akinori FUKUDA, Saburo TONOGAI1986 Volume 43 Issue 8 Pages 529-533
Published: August 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe relation between the structure and the viscoelastic properties of epoxy resins prepared from three-nuclei novolacs was studied. Five epoxy compounds were synthesized by the reaction of threenuclei novolacs with epichlorohydrin, and were cured with diaminodiphenylmethane as a hardener. From the measurement of temperature dispersion in the viscoelastic properties of the fully cured resin, glass transition temperatures (Tg), average molecular weights between crosslinking points (Mc), and front factors (φ) were obtained. Two conclusions were obtained; (1) epoxy resins prepared from three-nuclei novolacs gave cured resins with higher Tg, larger E′ in a rubber region, smaller Mc, and larger φ than those from two-nuclei novolacs; (2) the three-nuclei type resin with a higher degree of bend in the main chain had a larger Mc and a smaller φ, as same as the two-nuclei type resin.View full abstractDownload PDF (820K)
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