No abstract

Elastomeric compound development is a multi-objective optimization task, and it contains vulcanization packages that crosslink the matrix. The deciding factors for vulcanization systems are the nature of elastomer, service temperature, processing methods and vulcanizate properties. Accelerated sulfur and organic peroxide are examples of vulcanization systems; each has its advantages and shortcomings. The peroxide-based system shows a high level of temperature stability while its flexibility is inferior to sulfur vulcanization. This study is finetuning a hybrid vulcanization system containing a combination of ultra-fast accelerated sulfur and a peroxide system; it also optimizes the vulcanization package ratios concerning various rheological and vulcanizate properties with the help of the Taguchi method. Ethylene propylene diene rubber (EPDM) is chosen as the basic matrix due to its excellent viability and commercial application with both the vulcanization systems. The formulations are optimized to combine the advantages of both the vulcanization systems. The results indicate that the vulcanization is sulfur-driven, but peroxide influences by selecting the crosslink sites and type. The hybrid system uses more components, but proper optimization helps to reduce the quantity of vulcanization packages with an improvement in physio-mechanical properties; it also helps to reduce the discharge of carcinogenic accelerator by-products, such as nitrosamine.

Increasingly stringent in demand for a fuel-saving tyre with low rolling resistance, the application of silica filler is governing the tyre industry day by day. Unlike carbon black filled rubber compound, silica compound is rather complicated as it demands, a reactive mixing where, mixing parameters of internal mixer play a vital role in the degree of silanization reaction. In this paper, a design of experiments (DOE) is carried out to screen the factors that significantly affect the silanization reaction during mixing. Taguchi method with L 18 orthogonal array is employed to determine the significance of mixing parameters on the degree of silanization reaction. To quantify the significance of each mixing parameter on silanization, such as mixing temperature, mixing time, fill factor, feed door condition, ram pressure, and temperature control unit of Banbury mixer are explored. Key properties like Tan δ at 60 C, reinforcement index, and Payne effect (ΔG') are considered responses for the DOE. It was observed that the silanization temperature and time were the most influencing factor in silanization using the contribution plot. In contrast, ram pressure and feed door condition have the least significance on the degree of silanization.

Silica is the rubber industry’s most essential and cost-effective reinforcing filler after carbon black. The silica reinforcement mechanism with a non-polar elastomer is complicated by the presence of polar functional groups on the silica surface. This polar nature of silica causes filler-to-filler interaction by forming hydrogen bonds. Therefore, sizeable non-dispersed silica clusters remain in a non-polar rubber matrix. To avoid these strong filler-filler interactions and improve rubber/silica compatibility, the silica surface needs to be modified. This can be done using a coupling agent which has functional groups capable of linking both the rubber and silica. It has been discovered that when silica/silane coupling agents are present, the critical properties like rolling resistance and wet grip in the magic triangle of tire tread balance out better than carbon black formulations, bringing the system closer to the green tire goal. In this review article, the efforts made by both the rubber formulation development and chemistry to fully exploit the potential of silica/silane reinforcement for automotive tires are retrospected. Highlights on how compounding ingredients, process technology, functionalized elastomer, novel silanes, and the variant of silicas can enhance the magic triangle and silica-silane reaction mechanism are provided. In addition, the kinetics of silanization and measurements for the degree of silanization is also highlighted. Future research directions in this area are also touched upon. Hopefully, this review can stimulate future silica/silane scientific and technology developments for both academic and industrial-oriented requirements.

Recently, in the tire industry, carbon black has been replaced by silica as a reinforcing filler for the development of "green tires". The "green" claim comes from the fact that silica-reinforced materials help further reduce rolling resistance, save vehicle fuel and reduce CO 2 emissions to the environment.Silica-silane technology dramatically contributes to the field tire industries by saving fuel. However, unlike carbon black mixing, silica mixing is complicated as it involves several reactions inside an internal mixer. In this paper, we have evaluated the effects of mixing parameters and optimized the silica-filled elastomer compound using the design of experiments (Taguchi and Response surface method). Silanization temperature and time are found to be crucial parameters for silanization. Compounds mixed using optimized mixing parameters show superior performance properties compared to the control. Filler dispersion in the optimized batch was better and characterized using a scanning electron microscope (SEM). Tan δ @60 C as an indication of rolling resistance is improved by 23% indicating the better fuel economy of this system.