Production and test methods of natural rubber (NR) / styrene butadiene rubber (SBR) based bushings

Rubber materials nowadays have a very wide usage area, especially in automotive industry. Most of the rubber are used to make antivibration bushes, engine mounts, shock absorbers and connection points in the automotive industry. Especially, vibration, noise and shock inhibitors are designed with trial and error methods because the material structure is not well known. The main purpose of this study is to produce the natural rubber (NR) / styrene butadiene rubber (SBR) based antivibration bushes and to investigate the effect of NR/SBR ratio on the performance of antivibration bushes. Within the scope of the study, NR/SBR mixture, which was determined at different rates in the first stage, was prepared with 4 reference prescriptions. In this study, detailed information was given about all processes from raw material to production, such as, the production of rubber mixes, applied tests, used devices, surface treatment of metal materials, vulcanization parameters, and tests applied to the products. All rubber recipes were characterized by the rheologic and physico-mechanical tests. Apart from these tests, a dispersion test was carried out to see the filling distribution of rubber recipes. The prepared recipes are vulcanized on different process parameters (different temperature and time), which are determined by the rheological and the physico-mechanical properties. The results obtained by performing static and dynamic tests on anti-vibration bushings after vulcanization have been compared. All of these analyses were revealed the effects of elastomer ratios on durability performance of vibration-absorbing bushings and setting optimal recipe and process parameters. When the rheometric data of all the mixtures in this study were examined, an increase in the hardness values was observed with the increasing NR ratio. When the physico-mechanical test results were examined in NR/SBR mixtures, it was observed that when the NR ratio in the formulation increased and the SBR ratio decreased, the tensile strength increased and the breaking elongation values decreased. According to the dispersion test results, there is an increase in dispersion with the increase of NR rubber. As a result of the studies, it was observed that the mechanical properties of NR rubber are better than SBR rubber. When the vulcanization parameters was considered, it was observed that the formulation with high SBR ratio has a higher degree of vulcanization than the others. With the increasing NR ratio, the spring constants also increased, so hysteresis losses, which is an important indicator for product life performance, also increased. When all the data are evaluated together in formulations with NR/SBR mixture, the best results for product life performance were obtained with formulations NRSBR30 and NRSBR10, and also the most appropriate results were obtained in terms of vulcanization times.