Natural Rubber Blends and Based IPNs: Manufacturing Methods
Blending natural rubber (NR) with other polymers is a popular technique to enhance its mechanical, dynamic and thermal ageing properties, processability and oil resistance. To improve the desired properties of the final product, rubber based blends have to be mixed with various additives, shaped and cured. Rubber blends are difficult materials to process, because in both the raw and the compounded state they have both viscoelastic properties. Therefore, mixing of the additives with the rubber is a very important step in the rubber compounding. The primary functions of mixing are incorporation, dispersion and distribution of the other ingredients in rubbers. The latex-mixing method is an alternative to the conventional dry-mixing method which is to combine dry solid rubber and other compounding ingredients in mixing equipment. To soften the rubber, the long polymer chains must be partially broken by passing the rubber between rollers or rotating blades. The ingredients can be thoroughly mixed with the rubber to achieve uniform dispersion of ingredients. The quality of the compound are as a consequence of the combined effect of the unit processes of mixing, which would be dispersion of the filler, chain scission of the polymer, and bound rubber formation.