natural rubber

Natural RubberGlobal natural rubber consumption is split among tires (75%), automotivemechanical products (5%), nonautomotive mechanical products (10%), andmiscellaneous applications such as medical and health-related products (10%).Since the 1960s, the quality and consistency of natural rubber has improved, primarilybecause of the implementation of standard specifications defining arange of grades of rubber. Natural rubber is available in three basic types: technicallyspecified rubbers, visually inspected rubbers, and specialty rubbers.The American Society for Testing and Materials (ASTM) describes sixbasic grades of coagulated technically specified natural rubber which isprocessed and compacted into 34-kg blocks [3] (Table I). These six generalgrades of technically specified natural rubber are defined in more detail by therespective producing countries. Standard Malaysian Rubber (SMR), StandardIndonesian Rubber (SIR), and Thai Technical Rubber (TTR) expand therange of rubbers available. For example, two constant-viscosity StandardMalaysian Rubber CV grades are available, SMR CV50 and CV60 [2]. SMR10 and SMR 20 grades are also available as viscosity stabilized (SMR 10CVand SMR 20CV).The Rubber Manufacturers Association has a further set of standards forquality and packing of latex natural rubber grades. Table II defines the eight