Studies on Microbial Degradation of Natural Rubber Using Dilute Solution Viscosity Measurement and Weight Loss Techniques

Reduction of molecular weight of rubber polymers for easy absorption of compounding ingredients is critical in every rubber compounding operation. Yet, rubber mastication which is the current practice of achieving this is expensive, requiring high energy and equipment cost. To address this problem, microbial degradation of natural rubber (NR) and waste rubber tire (WRT) by Nocardia sp. strain 385A was studied using dilute solution viscosity measurement and weight loss methods. Solutions of NR and WRT in toluene were inoculated with the microbes (Nocardia sp. strain 385A) and kept in incubator. Incubation period varied between 0 to 10 weeks. The results obtained show that NR and WRT were mineralized and degraded by the microbes. Intrinsic viscosity values of both NR and WRT decreased with increasing period of incubation, indicating that degradation increases with increase in the incubation period. For the incubation periods investigated, WRT produced higher intrinsic viscosity values than NR due to the inhibitory effect of additives present in WRT to microbial degradation. Equivalent reduction in molecular weight obtained by rubber mastication technique was achieved by microbial degradation after 10 weeks incubation period. Rubber degrading bacteria can be useful for the disposal of discarded rubber products.