Design of rebound resilience measurement instrument and its use for elastomer testing

Rebound resilience measurement instrument is used to determine the elasticity of elastomer materials and the instrument is imported since it is not produced within our country. Before starting to the design of the instrument, the standards written for this purpose are determined and investigated so that the requirements of the instrument can be listed. The detailed design of the instrument is made and the finished products are determined according to the information gained. The parts of the instrument are manufactured using appropriate manufacturing techniques and the parts are assembled so that the instrument can operate. In order to verify the operation of the instrument, friction and reduced length of pendulum are calculated which are explained in standard test procedure. In addition, rebound resilience value of specimens are measured which are taken from Ferkan A.Ş. and Standard Profil A.Ş. The measured values are compared to the values measured by the given companies. Since the results do not meet the requirements, the design of the instrument is revised so that it meets the requirements. After the revisions, the verification tests are performed again and the instrument is verified. Four different natural rubber-based doughs are prepared which are different than the specimens used for verification tests. FEF 550 carbon black ratio is increased between NR 50 and NR 60 recipes. For NR-MT 50 and NR-MT 60 recipes, the ratio of FEF 550 is same with NR 50 and NR 60 recipes, respectively and same amount of MT 990 is added. The rebound resilience values of the prepared specimens are measured using the instrument. The rebound resilience values for recipes NR 50, NR-MT 50, NR 60 and NR-MT 60 are found as 71%, 74%, 52% and 70%, respectively. Addition of MT 990 to NR, which has 50 shore A stiffness, does not effect neither its stiffness nor rebound resilience. It is observed that addition MT 990 to NR recipe, which includes FEF 550 and HAF 330, increases the rebound resilience of the material from 53% to 70%. It is concluded that the rebound resilience varies according to the type of carbon black used for the recipe of the specimen and stiffness of the elastomer, however, different ratio of carbon black and stiffness values are necessary in order to find a relationship between the variables.