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Volume 44, Issue 4
Displaying 1-12 of 12 articles from this issue
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[in Japanese]1971 Volume 44 Issue 4 Pages 321-325
Published: 1971
Released on J-STAGE: April 16, 2008
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[in Japanese], [in Japanese]1971 Volume 44 Issue 4 Pages 326-335
Published: 1971
Released on J-STAGE: April 16, 2008
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[in Japanese]1971 Volume 44 Issue 4 Pages 336-340
Published: 1971
Released on J-STAGE: April 16, 2008
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(PART XII) SOFTENING PHENOMENON AFTER REMILLING OF STYRENE-BUTADIENE COPOLYMER RUBBER-GENERAL PURPOSE POLYSTYRENE RESIN BLENDSKUNIO SATAKE, KANTO SHINKI, TSUTOMU TERAOKA, SADAO IBE1971 Volume 44 Issue 4 Pages 341-348
Published: 1971
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSThe softening phenomenon after remilling of uncured blends of various styrene-butadiene copolymer rubbers on today′s market (styrene content: 23.5-48wt%, styrene block:0-18%) and general purpose polystyrene resin was mainly studied and the curves of blend ratio dependence of hardness and compression modulus (in logarithm) were examined, paying attention to the dispersion state of polymers.
And it was found that styrene-butadiene copolymer rubber-general purpose polystyrene resin blend forms a microheterogeneous blend system and the hardness and compression modulus change in “S” shaped curves against blend ratio. But random-type styrene-butadiene copolymer rubber and block-type styrene-butadiene copolymer rubber differ from each other in softening effect by remilling (the roll surface temperature: 70-90°C). The effect is more remarkable in case of random-type and the softening effect after remilling was not observed in case of some block-type rubbers. An influence of styrene content is small.
Further considerations on these differences in softening effect among different kinds of styrene-butadiene copolymer rubbers have shown us that the dispersion state of polymers is controlled by a strong mutual interaction between block parts of copolymers and general purpose polystyrene resin, which results in the above phenomenon.View full abstractDownload PDF (733K) -
(PART XIII) CHANGES OF MIXING STATES OF STYRENE-BUTADIENE COPOLYMER RUBBER AND GENERAL PURPOSE POLYSTYRENE RESIN BLENDS, PREPARED BY MILL BLEND WITH HEAT TREATMENTKUNIO SATAKE, KANTO SHINKI, TSUTOMU TERAOKA, SADAO IBE1971 Volume 44 Issue 4 Pages 349-355
Published: 1971
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSThe heat treatments on uncured blends of various styrene-butadiene copolymer rubber of today′s market (styrene content: 23.5-48wt%, styrene block: 0-18%) and general purpose polystyrene resin, prepared by mill blend, wera studied in the transition region of mixing states where the content of general purpose polystyrne resin in the blends wera 20-60wt%.
And the hardening and softening phenomena with heat treatment were found to slightly differ among different kinds of SBRs and they can be classified into a random SBR blend system and a block SBR blend system. A strong interaction between polystyrene block parts and general purpose polystyrene resin was considered to be responsible for this phenomena.View full abstractDownload PDF (621K) -
Seiji Sagawa1971 Volume 44 Issue 4 Pages 356-362
Published: 1971
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSRelation between activities (i.e., delayed action, rate of vulcanization, etc.) and chemical structures of sulfenamide-type delayed action vulcanization accelerators for rubber were quantum chemically studied.
Four parameters, which affect greatly on activities of the accelerators, were derived. They were electrophilic reactivity indices on sulfur atoms, radical reactivity indices on nitrogen atoms, π-bond orders between sulfur and nitrogen atoms, and π-electron densities on nitrogen atoms of sulfenamide linkages.
From those results, some new vulcanization accelerators of improved delayed action could be discovered.
Reaction mechanisms of the accelerators were also discussed briefly.View full abstractDownload PDF (408K) -
Hisayosi Sekiguchi, Masaaki Kakiuchi, Koichi Kameoka, Shuichi Okamoto1971 Volume 44 Issue 4 Pages 363-369
Published: 1971
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSAs mentioned in previous papers, the shear modulus of rubber differs evidently by its measuring method. The authers invented a shear modulus tester (SS-type Shear Modulus Tester) according to the theory of elasticity and rheology. Using this tester, the relation between the shear modulus Gss and the JIS spring harness was investigated. As the results of this investigation, the above-mentioned relation was clarified, and then the possibility to produce a simple and handy shear modulus tester by improving a penetrator, springs, gears, and a dial of the JIS spring hardness thester was found. This tester was produced trially and, as compared with SS-type Shear Modulus Tester, it was proved that it had allowable accuracy in practical usage.View full abstractDownload PDF (513K) -
STUDIES ON NATURAL RUBBER (PART IX)Yasuaki Kozai, Shinichi Yamasaki1971 Volume 44 Issue 4 Pages 370-374
Published: 1971
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSGraft copolymerization of acrylamide onto hydrochlorinated rubber was carried out in toluene using radical initiators.
Benzoyl peroxide, azobisisobutyronitrile and lauroyl peroxide were effective as initiators. The curves of the degree of grafting and the percent monomer grafted against the initiator concentration had maxima. The graft efficiency decreased with increasing initiator concentration, but the effect was not remarkable. The higher the concentrations of hydrochlorinated rubber and acrylamide, the better results were obtained. The optimum polymerization temperature and time were 80°C and 2 hours, respectively. As for the swelling of graft copolymer, as the degree of grafting increased, it increased in water but decreased in benzene, toluene and carbon tetrachloride. No soluble part was observed in benzene if the degree of grafting exceede 60%, and in water irrespective of the degree of grafting.View full abstractDownload PDF (340K) -
GRAFT COPOLYMERIZATION OF ACRYLIC ACID AND METHACRYLIC ACID ONTO NATURAL RUBBERYasuaki Kozai, Yoshiyuki Ikeda, Shinichi Yamasaki1971 Volume 44 Issue 4 Pages 375-381
Published: 1971
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSGraft copolymerization of acrylic acid and methacrylic acid onto natural rubber was investigated in toluene using radical initiators. As initiators benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) were effective for acrylic acid and BPO was more effective than AIBN for methacrylic acid. Generally, acrylic acid seemed to be more easily grafted than methacrylic acid.
Graft copolymerization of acrylic acid: The degree of grafting increased or reached a constant with increasing initiator concentration, monomer concentration and polymerization time. However, it was inversely proportional to the volume of polymerization solvent. The grafting efficiency was 90-95% independent of any variables except in the range of the high monomer concentration. The curves of the total conversion and the percent monomer grafting against the monomer concentration had maxima, but the other variables had the same effects as they had on the degree of grafting. The most adequate polymerization temperature was 80°C.
Graft copolymerization of methacrylic acid: The degree of grafting showed the same tendency as in the case of acrylic acid. The grafting efficiency increased with increasing BPO concentration and became approximately 60% irrespective of the polymerization time, if the monomer concentration was not extremely low or it was not at the very initial stage. However, it was inversely proportional to the volume of polymerization solvent and the polymerization temperature. As for the total conversion and the percent monomer grafted the total conversion was proportional to the polymerization temperature and the curve of the percent monomer grafted against the monomer concentration had a maximum. Other variables had almost the same effects as they had on the graft efficiency.
The appearance of graft copolymers obtained were similar both for acrylic acid and methacryic acid. They became less elastic, tough and lumpy, as the degree of grafting increased. With increasing degree of grafting the degree of swelling and the amount of soluble part became smaller in benzene, but greater in water and ethanol. This tendency was more remarkable in methacrylic acid-grafted copolymers than acrylic acid-grafted copolymer.View full abstractDownload PDF (514K) -
[in Japanese]1971 Volume 44 Issue 4 Pages 382-383
Published: 1971
Released on J-STAGE: April 16, 2008
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1971 Volume 44 Issue 4 Pages 383a
Published: 1971
Released on J-STAGE: April 16, 2008
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1971 Volume 44 Issue 4 Pages 383b
Published: 1971
Released on J-STAGE: April 16, 2008
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