Melt grafting of maleic anhydride onto SBR with a peroxide initiator has been studied by use of an internal mixer (Brabcnder plasticorder). The percentage of crosslinking (gel content) was measured by titration and the results was compared with FTIR spectrographs. It was revealed that both grafting and crosslinking reaction proceed simultaneously at all formulaticlls and depend on the amount of maleic anhydride and peroxide.High grafting with low gel content was achieved at low concentrations of maleic anhydride (1phr) and benzoyl peroxide (0.06phr).Processing parameters in eluding temperature and material feeding method and fill factor were studied.

This study treats one important aspect of starch-filled rubber compounds which is their rheological behavior. Starch-based SBR1712 masterbatches resulting from various formulations were prepared using a mini two roll mill and an internal mixer (Plastograph Brabender).The content in starch was varied from 0 to 50 phr. The effect of starch content on the rheological behavior was evaluated through the flow characteristics in the temperature range (130-160 °C) which matches that used in the vulcanization process. Four experimental techniques were considered to assess the mixing and the flow behavior of the materials: 1) Brabender mixer, 2) melt flow index, 3) capillary rheometer and finally 4) dynamic rheological properties through strain sweep experiments using a plate-plate rheometer. It came out that the four techniques used in the assessment of the rheological behavior of such materials are appropriate, complementary and successful. The melt flow index, and viscosity measurements indicate a resistant flow for the rubber and its starch composites. Even high temperatures do not seem to reduce the viscosity considerably.Nevertheless, small amounts of starch incorporated in the gum will ease the flow to some extent.The materials showed a pseudoplastic behavior, and storage made a slight change in their melt flow index. Morphological studies showed that the particles of starch were not destructed during the mixing and their interaction with the rubbery matrix is very poor.

The purpose of this work was to investigate the effect of application of copper(I) oxide (Cu2O) as an unconventional crosslinking agent of chloroprene (CR) and styrene-butadiene (SBR) rubber compositions. The use of Cu2O arises from the need to limit the application of ZnO as a CR crosslinking agent. The obtained results indicate that CR/SBR blends crosslinked with Cu2O are characterized by good mechanical properties and a high degree of crosslinking The results show that the proportion of both processing rubbers, as well as the amount of copper(I) oxide, influence the crosslinking of CR/SBR blends and the properties of the vulcanizates. Performing FTIR analysis has allowed the development of a crosslinking mechanism. Crosslinking presumably takes place according to the mechanism of Friedel–, Crafts alkylation reaction. Silica, chalk, china clay and nanofiller (montmorillonite modified with quaternary ammonium salt containing hydroxyl groups) were applied as fillers. Among the fillers, silica had the greatest impact on improving the properties. It is arisen from silica activity, unlike other used fillers. The AFM analysis allowed us to determine the miscibility of the rubbers and dispersion of fillers. Thermal analysis was performed to determine the changes occurring as a result of material heating. The low intensity of the peaks corresponding to the crosslinking of the CR/SBR blends may indicate a small amount of bonds formed during heating, or possibility is the formation of connections between chains with a low binding energy. The use of chalk, china clay or silica increases the thermal stability of the vulcanizates. Obtained vulcanizates were characterized by increased incombustibility. The study of combustion time in the air showed that the prepared vulcanizates did not support the burning.

Thermoplastic elastomers (TPEs) bring a combination of good plasticity of plastics and mechanical properties of elastomers that are important to component designers. These materials are especially used in the automotive industry to make a variety of parts, including strong shields. The injection process is one of the most common methods of making these polymers, which allows mass and industrial production. In this study, the injection process of elastomeric thermoplastic shield made of polypropylene / styrenebutadiene rubber + natural rubber (PP + SBR / NR) was simulated using Autodesk Moldflow software and the appropriate injection port location, optimal process conditions and possible injection defects Were discussed. Injection mold filling time, injection pressure, melt and mold temperature, cooling time, warpage and shrinkage are among the parameters that have been analyzed in this study. Also, possible positions of air trapping and weld lines were identified as the most common possible injection defects.

Nanocomposite vulcunizates based on styrene-butadiene rubber (SBR), organoclay and a conventional sulfur curing system were prepared by melt blending process in an internal mixer. In order to study the effects of the type of interfacial compatibilizer on the properties of SBR and clay nanoparticles, three types of compatibilizers, maleic anhydride grafted ethylene-propylene diene rubber (EPDM-g-MAH), acrylonitrile-butadiene rubber (NBR) and epoxidized natural rubber (ENR50) have been used. The nanocomposites have been compared together from view point of their curing behavior, rheological and mechanical properties. The developed microstructure and dynamics of the macromolecular chains in proximity of the clay nanolayers have been characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and melt rheo-mechanical spectroscopy (RMS). Curing behavior of the prepared nanocomposites has been evaluated using a rubber curing rheometer. EPDM-g-MAH and ENR50 showed to enhance the interactions between SBR chains into clay tactoids much stronger than NBR as a compatibilizer. These were consistent with the dynamic mechanical thermal analysis (DMTA) data as well as macroscale mechanical properties tested on the samples.

The tear strengths of some conventional accelerated-sulphur vulcanizates of styrene-butadiene rubber (SBR) with a sulphur to accelerator ratio of -1 .8, containing no filler,10, 30, or 50 parts per hundred rubber by weight (pphr) precipitated amorphous white silica filler type VN3 were measured. The tear tests were performed at different rates ranging from 0 .017 to 8.33 mm/s, at an angle of 180 and at an ambient temperature (–23°c) The tear strengths of the vulcanizates improved progressively and quite substantially with silica; a trend which continued strongly when the amount of silica in the formulation was increased to 50 pphr, but remained mostly unaffected by changes in the rate of tear. For instance, the tearing energy rose by almost two orders of magnitude, from -1 .5 to -100 kJ/m 2 at a tear rate of 0 .017 mmls, when 50 pphr silica was loaded into the rubber. Likewise, the hardness of the vulcanizates, which was measured at 24 .5 °C and a 15 s instant, was enhanced significantly from -35 to -65 Shore A, when silica was added and then increased progressively to its full amount in the rubbers.

The cure properties of some conventional accelerator/sulphur compounds of styrene-butadiene rubber (SBR) with a sulphur to accelerator ratio of ~1.8, containing no filler, and 10, 30, or 50 pphr rubber by weight precipitated amorphous white silica filler type VN3 were studied at 160°C by an oscillating disc rheometer curemeter. The optimum cure time, t95, of the compounds was lengthened substantially from 20 to 280 min when silica loading was raised to 50 pphr. The rate of cure calculated from the cure rate index, decreased sharply from 8.3 to 0.37 min–1 when the amount of silica in the mixes reached 50 pphr. Interestingly, the scorch time, ts2, of the compounds was not affected by the addition and increases in the amount of silica, and remained at about 8 min, although, there was some evidence that silica had interfered with the reaction mechanism of sulphur cure and reduced the extent of cure in the rubbers. Our results indicated that the compounds were fully cured when sufficient time i.e., up to 300 min for the mix with 50 pphr filler, was allowed for the reaction in the compounds at elevated temperature to complete.