Showing papers on "Styrene-butadiene published in 1975"

Starch Xanthide Reinforced Styrene-Butadiene Rubber: Compounding To Reduce Water Sensitivity:

Abstract: ONV~NTI©NAL RUBBERS SLOWLY absorb water during prolonged water immersion by a complex process involving both reversible and irreversible mechanisms without reaching a swelling equilibrium [1, 2} . Usually water absorption is of little consequence, but it can be deleterious for rubber articles with thin cross-sections or acute profiles, especially if they are made from inherently watersensitive elastomers or if they contain water-sensitive components [1, 2) . The rate and extent of water absorption by starch xanthide reinforced articles depend on their size and shape and on frequency and duration of water immersion [3, 4] . For starch xanthide reinforced rubbers, the effect of 90 days’ water immersion is completely reversible by drying, even for specimens with large surface-tovolume ratios [4]. Our previous studies showed that the rate of water absorption could be greatly reduced by increasing the extent of crosslinkage of the starch xanthide, by improving adhesion between starch and rubber phases and by adding carbon black or other fillers [3, 4]. Both resorcinol-formaldehyde (RF) and an aminosilane coupling agent were effective in reducing swelling rates when incorporated in small proportions. However, each interfered with normal vulcanization; RF decreased and the aminosilane increased cure rates [4]. Accordingly, compounding was studied in more detail to find combinations of RF, aminosilane, and fillers that would reduce

Pressure-sensitive adhesive tape substrate

Abstract: A pressure-sensitive adhesive tape substrate consisting of polyolefinic film (such as polypropylene, polyethylene or more especially an ethylene propylene copolymer) contains a thermoplastic elastomer, usually in an amount below 30 parts by weight per hundred parts of polyolefine and, for example, polyisobutylene or styrene butadiene block copolymer, in order to impart increased splitting resistance in a transverse direction.

Styrene-butadiene copolymer latices containing carboxyl groups

Abstract: Low-foam carboxylated styrene-butadiene-latices obtained by the emulsion polymerization of monomer mixtures of: 73.5 to 18.5 parts by weight of butadiene; 20 to 80 parts by weight of styrene; 0 to 10 parts by weight of acrylonitrile; 0 to 5 parts by weight of ethylenically unsaturated carboxylic acid amides or methylol derivatives thereof; and 1.5 to 10 parts by weight of ethylenically unsaturated carboxylic acids; Wherein the ethylenically unsaturated carboxylic acids consist of a mixture of: 1.0 to 4 parts by weight of acrylic acid and 0.5 to 6 parts by weight of methacrylic acid And wherein less than 0.5 parts by weight of anionic emulsifiers are used for polymerisation. The latices can be used inter alia as an impregnating material for soft non-wovens, cardboards and fiber fleece carpets.

High solids styrene-butadiene emulsions

Abstract: An improved process for preparing high solids predominantly styrene-butadiene copolymer aqueous emulsions is disclosed which process comprises pre-emulsifying a portion of the monomers to be used in forming the copolymer and adding the resulting pre-emulsion to a mixture of the remainder of the monomers, all maintained at an aqueous solids content between about 50 and 75 weight percent, utilizing as initiators about 0.1 to about 2.0 percent, by weight, based upon the total monomer weight, of a lypophillic initiator and about 0.01 to about 0.2 percent, by weight on the same basis, of a hydrophillic initiator.

Thin-layer chromatographic identification of chain architectures of styrene - butadiene copolymers.

Abstract: The feasibilities of thin-layer chromatography as a tool to identify the chain architecture of given copolymer samples have been investigated. To this end, styrene—butadiene (SB) block copolymers with known chain architecture were prepared and used as reference samples. Preliminary TLC experiments on these samples indicated that the random, tapered, diblock and triblock SB-samples could be chromatographically distinguished from one another under suitable development conditions. By applying the procedures thus established, the chain architecture of various commercial SB-products could be identified without appreciable interference from the molecular weight and composition.

Carbon-13 nuclear magnetic resonance spectroscopy of polymers. Part V. Monomer sequence in styrene–butadiene copolymers

Abstract: The complete characterisation of styrene-butadiene copolymer in terms of the 16 diads is achieved from the intensities of the 17 high-field peaks. Percentage compositions in terms of the four monomer units [styrene and 1,2-(v), cis-(c), and trans-(t) 1,4-linked butadiene] derived in this manner correlate well figures obtained from low-field peaks.Average block lenghts for each unit as well as block lenghts for mixed units are derived: cis- and trans-1,4-linked butadiene units show a marked preference to block together and block or unit styrene and 1,2-linked butadiene units occur preferentially between trans-1,4-linked butadiene units. Styrene possesses the greatest tendency to block.The relative content of butadiene units (t,c,v) was not systematically affected by the percentage of styrene. The distribution of the butadiene diads tt, tc, ct, and cc was virtually constant below 35 mole % styrene. The proportions of diads containing vinyl (v) and/or styrene units showed much greater variation.

Carbon-13 nuclear magnetic resonance spectroscopy of polymers. Part IV. Peak assignment for styrene–butadiene copolymers

Abstract: Twenty-six peaks in the 13C n.m.r. spectra of 12 samples of styrene–butadiene copylymer are assigned to individual carbon atoms, in various diad environments.

Method of treating synthetic polymer latex of styrene-butadiene or polyisoprene to make solid polymer derived therefrom re-dispersible to a latex

Abstract: A method of treating synthetic polyisoprene and styrene butadiene latices comprising adding to the latex particular redispersing agents so that the solid rubber obtained when the water is removed from the latex is redispersible. Various redispersing agents are described including urea with supplementary agents. Reconstituted latices obtained from such redispersible solid rubbers have comparable properties with freshly prepared latices.

Simplified method for reclaiming styrene butadiene rubber compound

Abstract: SBR系加硫ゴム粉末を用い, 加硫ゴム粒子表面を中心とした解重合反応を加熱式かき混ぜ装置や加熱式ロール機を用いて検討し, 併せて再生ゴムの物性も調べた.加硫ゴムの粒子径は, 解重合反応に大きな影響を与え, 粒子が小さいものほど解重合しやすい. また解重合条件を適当に選択すれば, 粉末ゴムの粒子が4メッシュぐらいまでは再生可能である. 再生剤として, ペプタイザーのみを用いた場合と再生油を併用した場合では, 後者のほうが解重合効果は大である. 再生ゴム加硫物の引張強さと解重合度の間には相関関係が認められ, ゴム炭化水素に対するクロロホルム溶解量が, 17～20%で引張強さの最大のものが得られ, かつその値は解重合する前の値の60～70%のものである. しかし動的性質は相当劣っている.

Carbon-13 Nuclear Magnetic Resonance Spectroscopy of Polymers. Part IV. Peak Assignment for Styrene-Butadiene Copolymers

Abstract: Twenty-six peaks in the 13C n.m.r. spectra of 12 samples of styrene–butadiene copylymer are assigned to individual carbon atoms, in various diad environments.

A relationship between network chain concentration and time dependence of rupture for SBR vulcanizates. [Styrene-Butadiene Rubber

Abstract: The failure properties of crosslinked elastomers are influenced by variables such as the test rate, test temperature, chemical nature of the elastomers, degree of crosslinking, etc. For an elastomer with a fixed degree of crosslinkingthe time dependence of both the stress- and strain-at-break, when determined as a function of the test rate and test speed, can be correlated using a time–temperature shift such as the WLF aT shift factor. When a similar study is carried out with a sample having a different degree of crosslinking, the time dependence of both the stress- and strain-at-break is shifted along the time scale. It is demonstrated here that the time dependence of failure obtained as a function of the degree of crosslinking can be superposed on a master curve by the use of a time shift factor whose value depends directly on the degree of crosslinking.