Properties Of Styrene-butadiene Rubber Vulcanizates Research Articles

Effects of the Synergy of Hardness and Resilience on the Akron Abrasion Properties of SBR Vulcanizates

The hardness (H) and resilience (R) of rubber vulcanizates were combined together in this paper, named as hardness–resilience product (H4R), and its relationship with the Akron abrasion loss was investigated using various styrene-butadiene rubber (SBR) vulcanizates possessing specific hardness and resilience characteristics as samples. For the unfilled SBR vulcanizates with different chain microstructure, possessing high elastic resilience and low hardness, the results showed that their Akron abrasion loss had a good linear relationship with the log(H4100R). This linear relationship also occurred when these SBRs were filled with 50 phr carbon black. For two particular types of SBR, after being filled with different fractions of carbon black and aged for different times, all their Akron abrasion losses (including unaged, aged for 24 h, and aged for 48 h) also had a good linear relationship with the log(H4100R). However, this linear relationship weakened for one of the SBRs after being aged for 48 h. In the high H4R region (the carbon black fractions being 60 and 70 phr), the data obviously deviated from the fitting curve due to the high hardness of the aged vulcanizates. However, after being filled with 50 phr of various kinds of carbon blacks, the relationships between abrasion loss and log(H4100R) were also approximately linear, with the correlation coefficient of the fitting curves being 0.99966 and 0.99878, respectively, for the two types of SBR.

Effect of Phenol-CNSL-Formaldehyde Copolymer on Thermal Ageing of SBR

Cashew nut shell liquid (CNSL) is a cheap and renewable agro by-product that consists mainly of substituted phenols. A CNSL-based resin was used in this study to modify the properties of styrene-butadiene rubber (SBR). The resin was a copolymer obtained by condensing a mixture of phenol and CNSL with hexamethylenetetramine. The effect of the resin on the ageing properties of SBR vulcanizates was studied by following the changes in tensile strength, elongation at break, modulus and tear strength. CNSL directly and CNSL-based resins with different P:F ratios were incorporated into SBR and the physical properties determined. Comparison of the properties of the aged material containing CNSL resin with those of specimens not containing the resin shows improved ageing characteristics with respect to tensile strength, modulus and tear strength.

Effect of Some Polymeric Phenolic Antioxidants on the Properties of SBR Vulcanizates

ABSTRACT Polymeric antioxidants can be useful in the protection of styrene-butadiene rubber (SBR) against thermal oxidative aging as an alternative to the low molecular weight ones, which migrate out of the rubber articles. Three polymeric compounds were prepared and incorporated into SBR mixes to be evaluated as antioxidants in comparison with the commercial antioxidant, N-isopropyl-N′-phenyl-p-phenylenediamine (IPPD). The rheometric characteristics of the produced SBR mixes were measured and the cure time was determined. The mechanical, swelling, extraction, and compression properties were studied. The results obtained revealed that poly(4-mercaptophenyl)acrylamide has superior effect in the protection of SBR articles against thermal oxidative ageing.

Effect of fillers and additives on the properties of SBR vulcanizates

Methacrylic acid (MAA) and methyl methacrylate (MMA) were used as additives for peroxide-cured styrene–butadiene rubber (SBR) filled with three inorganic fillers with different particle sizes and surface activity, for example, MgO, Mg(OH)2, and BaSO4. The experimental results show that the introduction of MAA can improve the mechanical properties of SBR vulcanizates filled with MgO, Mg(OH)2, or BaSO4. A small amount of MAA leads to significant increases in the modulus, tensile strength, and tear strength. MMA has little effect on the mechanical properties of the SBR vulcanizates. The SEM micrographs show that MAA can improve the interfacial bonding between SBR and the three kinds of fillers. The SBR–filler interaction was studied by Kraus plots. The relationship between the SBR–filler interaction and the mechanical properties was explored. m, a characteristic constant of a filler–SBR matrix, represents the interfacial bonding between fillers and SBR and the accumulated structure of the fillers. At a given ϕ, a high value of m means a strong interaction between SBR and the filler and, therefore, strong mechanical properties. The Payne effect of the SBR vulcanizates was observed, and the vulcanizates have low storage moduli at high strains and high storage moduli at low strains, and the moduli are nonlinear and increase the nonlinearity as the filler content increases. The loss moduli and loss factor reach their maximums at moderate and high strain amplitudes, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 775–782, 2003

Effect of Different Inorganic Fillers on the Physical Properties of Styrene-Butadiene Rubber Vulcanizates

The effect of different inorganic fillers such as lead silicate (amor phous or crystalline), burnt mazote boiler deposits (BMBD), aluminium oxide and ilmenite (FeTiO3) on the physical properties of different filled styrene- butadiene rubbers (SBR) has been investigated. The rate of vulcanization was increased according to the following order: lead silicate (amorphous or crystal line) > BMBD > aluminium oxide > ilmenite. Lead silicate of different types and BMBD were found to increase the tensile strength and resistance to abrasion. Dielectric constants (∈) for some of the com posites were determined. The lower (∈) values were obtained in the presence of aluminium oxide, burnt mazote and ilmenite while those obtained in the pres ence of different types of lead silicate were found to be higher.

The Properties of Filled Copolymer Vulcanizates

In our previous paper1) of this series the properties of styrene-butadiene rubber vulcanizates in tensile fracture was discussed. In this paper the properties of three copolymer vulcanizates in tensile fracture are studied, namely isoprene-butadiene, styrene-isoprene and methyl methacrylate-isoprene, and the following conclusions have been obtained.(1) The fracture in the vulcanizates of these copolymers compounded with carbon black is mainly due to scission in the molecular chains of polymer, and there is almost no scission in the bonds between the rubber molecules and the surface of the carbon black.(2) The temperature which affords the maximum value of ultimate elongation depends entirely on the transition temperature Tg, though the rubbers used may vary in average molecular weights per piece, in the network chain densities and in the combined sulfur structure.(3) The ultimate elongation at reduced temperature is little affected by the composition of two copolymers that do not differ markedly in Tg of homopolymer, as in the isoprene-butadiene system, while the elongation is thought to be decreasing with the increasing variance between the two component copolymers in Tg of homopolymer. For instance the elongation of styrene-isoprene copolymer decreases with increased content of styrene.