Natural Rubber and Bio-based Thermoplastic Elastomer
This chapter focuses on the introduction of natural rubber (NR) source, polymerization, modification, application, recycling, and future development. Isomerase enzyme is considered to function as the polymerization initiator, and metal ions (Mg, Mn, etc.) function as activators. One important category of NR chemical modification is halogenation, which is the introduction of halogen elements to the double bonds of isoprene units. It is found that a longer reaction time would result in a higher hydrogenation degree. It is reported that with a hydrogenation of 48%, the modified NR possessed better thermal stability and ozone resistance during vulcanization. The advantage of NR epoxidation is that it can improve NR properties, including air permeability, oil and solvent resistance, hardness, and damping. It is found that indirect degradation and elemental analysis show higher error level and consequent lower accuracy; these two techniques are mainly applied for indicative purposes only.