Strain-Induced Crystallization of Natural Rubber and Isoprene Rubber Studied by Solid-State NMR Spectroscopy

An elastomer is a polymer material that has the ability to resume its shape afterlarge deformation. Among various types of elastomers, natural rubber (NR) is the most typical one and an indispensable material for many industrial and household applications, such as tires, belts, gaskets, gloves, soles, rubbers, foam mattresses and so on. Because of the limited production of NR, a large amount of synthetic NR is synthesized, isoprene rubber (IR), to fulfill the requirement of industry and human society.The versatility of NR is mainly due to its outstanding tensile properties and the good crack growth resistance, which originates from crystallization under elongation. Many experimental techniques including X-ray diffraction (XRD), Transmission electron microscopy (TEM), birefringence, DSC and nuclear magnetic resonance (NMR) have been applied over the years to investigate the crystallization of NR under external strain.In this study, we designed a new and entire NMR system for characterizing crystallinity of rubber samples and successfully determined crystallinity of NR and IR under various strains. We will further investigate crystallinity of NR nanocomposite with carbon black and blends with other rubbers. Our developed NMR tools will be technique transferred to Bridgestone America for future research.