The aim of this work was to evaluate peroxide systems with and without coagents as cross-linking agents for rubber compounds in tires, which are usually prepared with sulfur. Natural rubber (NR) and styrene-butadiene rubber (SBR) formulations were prepared in open and closed mixers using an NR/SBR compound cured with sulfur as a reference. The physical properties (hardness, tensile strength, tearing, and abrasion) and dynamic mechanical behavior of the NR/SBR compounds cured with different cross-linking agents were evaluated. The NR/SBR compounds cured with only peroxide had poorer properties than did the vulcanized compound. On the other hand, the coagents were quite effective, and the NR/SBR compounds with BIS F40 þ Retilink T40 (compound 10) or BIS F40 þ T70A (compound 11) had properties similar to those of the reference compound. Compound 10 and the reference compound yielded similar tan d values from dynamic mechanical analysis at 60 and 0 C, which are related to the rolling resistance and wet traction, respectively. The results demonstrate the possibility of using a peroxide/coagent NR/SBR compound instead of a sulfur-cured compound for tire tread applications without the loss of desirable properties and with lower costs and processing times.

ABSTRACT

An anomalous velocity cloud near l= 349 ~ b= + 3 ~ was investigated by Cuguon (1968). The authors made a new set of observations in order to obtain a more complete picture of the feature, including the region originally out of Cugnou's limit of observation. A comparison with optical and radio observations was made and several possibilities of interpretation as to the nature of the object were analyzed.

No abstract