Physical Properties Of Vulcanizates Research Articles

HYBRID SILANE TECHNOLOGY IN SILICA-REINFORCED TREAD COMPOUND

ABSTRACT The use of a silane coupling agent in silica-reinforced tread can effectively improve silica dispersion in the rubber matrix and strengthen the interfacial interaction between the rubber and filler; this is beneficial to the enhancement of tire grip under wet conditions and reduces tire rolling resistance. The monofunctional silane n-octyltriethoxysilane (OTES) can react with the silanol group of the silica surface and hence improve silica dispersion. It can also suppress silica reaggregation during tire processing. Two hybrid silanes, OTES and 3-mercaptopropylethoxy-bis(tridecyl-pentaethoxy-siloxane) (Si747) or OTES and bis(triethoxysilylpropyl)tetrasulfide (TESPT), were filled in silica-reinforced tread compounds. The effect of the two hybrid silanes on the silica was investigated via Fourier transform infrared spectroscopy and thermogravimetric analysis. The processing ability of the silica-filled compounds and the performance of the vulcanizates were also investigated. Our experimental results show that OTES is able to further react with the silica following reaction between the TESPT and silica and that it should be added when the molar amount of TESPT or Si747 is constant, to prevent reduction of the cross-link density. Furthermore, the addition of OTES can extend the scorch time, especially in Si747 and OTES compounds. In addition, OTES can improve silica dispersion and only has a slightly negative effect on the physical properties of vulcanizates.

The Effects on the Cure Characteristics and Physical Properties of Bamboo Activated Carbon Filled Styrene Butadiene Rubber (SBR) Compounds

The role of activated carbon (AC) in rubber compounds was investigated to better understand the reinforcing mechanism. The activated carbon filled styrene butadiene rubber vulcanizates (SBR-AC) using bamboo activated carbon as filler were prepared by using two-roll mill and cured at 160 °C. AC filler loading from 10 to 50 phr (part per hundred rubber) were used in this study. Study into the influences of filler loading on the cure characteristics, swelling behaviour and physical properties (hardness and resilience) of SBR-AC vulcanizates were carried out. It was observed that SBR-AC vulcanizates has better cure characteristics compared to the styrene butadiene rubber gum vulcanizate (SBR-GV) which is a non-filled vulcanizate. The results showed that the scorch time (ts2) decreased with increasing filler loading. The cure time (tc90) slightly decreased up to 20 phr before a rise as the filler loading increased. The minimum torque (ML) of SBR vulcanizate increased and the maximum torque (MH) decreased up to 20 phr but then increased with increasing filler loading. The cure rate index (CRI) of SBR-GV vulcanizate was higher than that of all SBR-AC vulcanizates. Up to 20 phr of filler loading, the CRI increased before a decline occurred as the filler loading increased. As expected, the hardness value of SBR-AC vulcanizates was higher compared to SBR-GV vulcanizate which has lower resilience. The hardness and crosslink density showed an increasing trend meanwhile the resilience was adversely affected by the increase in filler loading. Bamboo activated carbon showed some potential enhancement on the reinforcing and physical properties of the vulcanizates.

配合剤の基礎から最新技術―２ 白色フィラーの特徴

It is well known that carbon black has superior reinforcement effects on physical properties of vulcanizates. Inorganic fillers, such as silica, kaolin clay, and calcium carbonate, exhibit similar effects on physical properties of vulcanizates by surface treatment with silane coupling agents and addition of modified polymers. The properties of inorganic fillers and its surface treatment for development of high-performance and high-functional vulcanizates are reviewed in this paper.

白色フィラー配合ゴムの性質と高性能化 １．白色フィラーの性質とゴム配合効果

Because of lower reinforcement effects on physical properties of vulcanizates than carbon black, inorganic fillers such as silica have been used in a rubber industry supplementary. Recently, necessity of inorganic fillers is recognized for development of high performance and high functional vulcanizates. This paper is referred to properties of inorganic fillers and vulcanizates loaded with them and possibilities of development with loading inorganic fillers.

A comparison of white rice husk ash and silica as fillers in ethylene–propylene–diene terpolymer vulcanizates

AbstractWhite rice husk ash (WRHA) and silica filled ethylene–propylene–diene terpolymer (EPDM) vulcanizates were prepared using a laboratory size two‐roll mill. Curing characteristics and physical properties of vulcanizates were studied with respect to the filler loading and filler type. Filler loading was varied from 0–50 parts per hundred resin (phr) at 10 phr intervals. Curing was carried out using a semi‐efficient vulcanization system in a Monsanto rheometer. Enhancement of the curing rate was observed with increasing WRHA loading, whereas the opposite trend was observed for silica‐filled vulcanizates. It was also indicated by the maximum torque and Mooney viscosity results that WRHA offers processing advantages over silica. Compared to the silica‐filled vulcanizates, the effect of filler loading on the physical properties of WRHA‐filled vulcanizates was not significant. According to these observations, WRHA could be used as a diluent filler for EPDM rubber, while silica can be used as a reinforcing filler.© 2001 Society of Chemical Industry

Diimide reduction of cis-1,4-polyisoprene with p-toluenesulphonylhydrazide

The hydrogenation of cis-1,4-polyisoprene with diimide generated in situ from p-toluenesulphonylhydrazide (TSH), was investigated under various conditions. In aromatic solvents at 100–140°C, the rate of hydrogenation was increased with increase in concentration of polyisoprene and of TSH. Part of the polymer was depolymerized and cyclized during the reaction. Increasing the hydrogenation tended to decrease the rate of sulphur vulcanization, of the compounded rubber and the physical properties of vulcanizates were poor. The reaction of polyisoprene rubber with TSH, was also carried out in a solid state at 140°C for 20–60 min. It was found that by using a large amount of TSH hydrogenation and cyclization of rubber occurred. The quantity of TSH used as a blowing agent, for rubber in the manufacture of sponge rubber, i.e. 5–10 phr, did not cause hydrogenation.

New Dispersible Carbon Blacks

Abstract It has been shown that the process of pelletization of a carbon black carried out to permit easier transportation through bulk handling, leads to irreversible changes in properties. There are strong indications that the pelletization process of carbon black involves free radical reactions, leading to chemical particle bonding. The superior physical properties of vulcanizates reinforced with unpelletized blacks indicate that chemical particle bonding is undesirable, since it reduces interaction between carbon black particle and polymer. In order to overcome chemical bonding of carbon black particles during pelletizing, carbon blacks were prepared the particles of which were covered withat least a monolayer of an oleaginous material compatible with the polymer. It was found that the product obtained could be pelletized to form predominantly physically adhering particles. These carbon black compositions disintegrate spontaneously in solvents for the oleaginous liquids, in view of the dissolution of the pellet binding material. The new carbon black compositions are ideally suited for black solvent masterbatching. In addition, they also show improved physical properties upon dry mixing with polymers in conventional dispersing equipment. Finally, they provide for a simple, rapid and efficient way to incorporate processing oils into polymers in conventional mixing equipment.

Vulcanization of Elastomers. 38. the Reactivity of Synthetic Rubbers. I

Abstract Investigations relating to the development of other than conventional procedures for vulcanizing synthetic rubbers, especially cis-1,4-polybutadiene, are reported. The results were as follows: 1. cis-Polybutadiene and trans-polybutadiene containing 2% and more of 1,2 addition can be crosslinked to a certain extent by means of dibenzothiazolyl- or dibenzimidazolyldisulfide. 2. cis-1,4-Polyisoprene undergoes a much lower degree of crosslinking with the above disulfides. 3. The physical properties of vulcanizates are considerably improved if the molecules of the added disulfides contain groups which react with isocyanates. When diisocyanates are incorporated, supplementary crosslinking sites are formed. 4. The crosslinking of cis- and trans-polybutadiene via DBIS and Desmodur 15, in the absence and presence of black is described in more detail. The usual physical properties are determined and compared with those obtained when sulfur is used as the vulcanizing agent.

Chemistry in Carbon Black Dispersion

Abstract The properties of carbon black and their effect on the physical properties of rubber vulcanizates have been extensively reported. The importance of particle size, reticulate structure, and surface characteristics are generally accepted. The beneficial effects of carbon black are believed to be due in large part to strong adsorption of rubber molecules on the carbon black surface. Many investigators have described the physical nature of this adsorption and have related it to the surface properties of the carbon black. Chemical bonding has also been suggested as being an important factor in the surface interaction between carbon black and rubber. The contribution of chemical bonding to the dispersion of carbon black and its effect on the physical properties of vulcanizates is the subject of the present paper. Gerke, Ganzhorn, Howland, and Smallwood and Bradley found almost twenty years ago that, when rubber-carbon black mixtures were heated at temperatures of 275–400° F, vulcanizates prepared from the mixtures had lower electrical conductivity, lower hysteresis, lower durometer hardness, higher modulus at large deformations, and greater resistance to abrasion than did vulcanizates of the corresponding unheated mixtures. These changes were ascribed to changes in the dispersion of the carbon black. Experimental data will be presented in this paper which suggest that these changes in carbon black dispersion are the result of chemical reactions between carbon black and rubber.