Optimize Technical Properties with Master Batch Blends in RSS/Scrap Rubber Tire Retread Compounds

Nowadays, polymers as a group of materials have occupied in major areas of human lives. Natural rubber (NR) is a substitute for synthetic rubbers in majority of applications, and higher prices of petroleum-based products have resulted in higher cost involvements in NR rubber compounds. This has resulted in partial replacement of higher grade Ribbed Smoked Sheet (RSS) NR with lower grade scrap rubber in most of the rubber products, especially retreading tire compounds. In preparation of rubber mixes, usual practice is to mix both types of rubber together and added with carbon black, oil and other ingredients subsequently, according to an order. Aim of this study was to get optimum technical properties of a selected retreading tire compound of (80%) RSS and (20%) scrap rubber with the use of master batch preparations; i.e. the amount of carbon black was added separately into two types of blended rubber and mixed separately. The master batch mix design with 80% carbon black incorporated into RSS and 20% carbon black incorporated into scrap rubber showed a better balance of technical properties than the properties obtained with other master batch mix designs and also the normal mix design.