Journal of Elastomers & Plastics

A solid product SiO₂D has been obtained as a result of subjecting the tread of ‘green’ tyres to pyrolysis-cum-water vapor. It has been found by IR-FTIR and EDXRF spectroscopy that the product contains 65% of SiO₂, 30% of carbon, 3% of ZnO, and 2% of other components. The mechanical and dynamic properties, and SEM micrographs of the vulcanizates of model sSBR/BR-based blends having a different SiO₂D filler content have been compared to those of vulcanizates filled with conventional SiO₂ and carbon black at a 2 : 1 ratio. Composites comprising ZnO as well as such comprising zinc salts of long-chain fatty acids have been investigated. Differences have been established neither in the mechanical properties (Modulus 300, tensile strength, abrasion, etc.) nor in the dynamic properties (heat build-up, tan δ, etc.) of the vulcanizates filled with SiO₂D and of those filled with conventional SiO₂ and carbon black at a 2 : 1 ratio. The size of SiO₂D particles has been found to be the same as that of conventional SiO₂. Their distribution in the rubber matrix also does not differ.

Recycling waste tires being important for both economical and environmental reasons, ground tire rubber can be blended with other polymers, modifying their properties. In order to characterize and explain these modifications, an experimental study was carried out concerning the improvement in the dynamic damping properties when adding recycled ground tire rubber (GTR) fillers to an elastomeric matrix (ethylene vinyl acetate, EVA).To evaluate the influence of both the GTR and the porosity in a GTR/ EVA composite, three samples have been elaborated by injection:the EVA matrix alone, a GTR/EVA composite, and a GTR/EVA porous composite. Dynamic measurements of the samples were performed using dynamic mechanical thermal analysis. The Young’s modulus and loss factor of these materials are estimated using the frequency—temperature equivalence introduced by Williams—Landel—Ferry expanding the measurement of the dynamic properties over a wider range of frequencies. This method showed that in low-frequency bandwidth, the loss factor has been improved by the addition of GTR to the EVA matrix. The α-relaxation study showed lower activation energy for both the GTR-filled composites leading to the conclusion that the mobility of the polymer chains has been improved by addition of GTR. The impact behavior study carried out using a weight drop test experiment also concluded to better impact energy absorption for the GTR-filled composites at the expense of a larger maximum displacement.

The mechanical properties and gas permeability of natural rubber/bromobutyl rubber blends were investigated when using epoxidized natural rubber (ENR) as a compatibilizer. The blend composites used in this study were composites of commercial precipitated silica. Several types of layered silicates were investigated here as secondary fillers due to their high-aspect ratio platelet structures, which could help delaying the gas permeation rate. These fillers include talcum, montmorillonite clay, and kaolinite clay. We found that, ENR could promote faster cure and could improve the mechanical properties, compression set, and abrasion resistance of the composites with significant improvement in its gas barrier property. Among different types of fillers, talcum could provide superior gas barrier property to other types of fillers, even though the strength and modulus of talcum composite were still inferior to those of other composites. However, the addition of ENR to talcum composite did not further improve its gas barrier property further, though it could improve the other properties.

Adhesion properties of epoxidized natural rubber (ENR 50)-based adhesive were studied in the presence of magnesium oxide. Coumarone-indene resin and toluene were used as the tackifier and solvent, respectively. A SHEEN hand coater was used to coat the adhesive on a polyethylene terephthalate substrate at 30, 60, 90, and 120 μm coating thickness. Viscosity was measured by a HAAKE Rotary Viscometer whereas loop tack, peel and shear strength was determined by a Llyod Adhesion Tester operating at 30 cm/ min. Results indicate that viscosity of adhesive increases steadily with magnesium oxide content. Loop tack and peel strength show maximum values at 30 parts per hundred parts of rubber of magnesium oxide where maximum wettability occurs. The 60-μm coated sample consistently exhibits the highest tack and peel strength. Shear strength, however, decreases with increasing magnesium oxide loading for all coating thickness investigated in this study.

The thermodynamic properties of styrene-b-butene/ethylene-b-styrene, styrene-isoprene-styrene, and naphthenic oil, were investigated by means of inverse gas chromatography using 13 different kinds of solvents as the probes. Some thermodynamic parameters such as specific retention volume, weight fraction activity coefficient, Flory—Huggins interaction parameter, partial molar heats of mixing and solubility parameter, etc. were obtained to judge the interactions and the solubility between the polymer and solvents and the solubility of the polymers in these solvents. The results indicated that n-pentane, n-hexane, chloroform, tetrahydrofuran, and diethyl ether were good solvents for these polymers at experimental temperatures. The solubility parameter of styrene-b-butene/ethylene-b-styrene, styrene-isoprene-styrene, and naphthenic oil were calculated to be 16.99, 16.84, 14.39 (J/cm³)^1/2 at 298.15 K by inverse gas chromatography, respectively, which were consistent with that obtained by intrinsic viscosity method, small group contribution method, or solubility parameter-surface tension method.