Thermoplastic elastomer (TPE) produced by dynamic vulcanization which is one of the reactive processing is generally called thermoplastic vulcanization (TPV).
It is considered that, in the mixing process of TPV, the crosslink reaction and the EPDM dispersion in PP proceeds simultaneously. Therefore, the phase structure of TPV is complex and it is very difficult to analyze the kneading states. Since the slight difference of kneading states is known to lead to the large differences in the physical properties such as the extrusion processability and the surface appearance of the products, the conventional and exact testing methods to estimate TPV kneading state is required at TPV mixing plant.
It was found that an apparent activation energy (E_a) calculated from the temperature dependence of dynamic viscosity modulus is an effective index for measuring the degree of crosslink. Also the degree of EPDM dispersion was quantified by dynamic elasticity modulus change ratio (G_r) between G* at the strain of 20% and 1%. These indices can be calculated simply and easily from dynamic viscoelastic results and can be applied to estimate the kneading state of the TPV compound.

X-ray Photon Correlation Spectroscopy (XPCS) is a technique studying materials dynamics with scattering of coherent X-rays. We describe the basics of XPCS and applications of XPCS for rubbery materials.

Mechanochromism is color change phenomenon in response to mechanical stress. The importance of mechanochromic polymers has increased due to the application to stress detection and damage prediction of the polymeric materials. In the present review, some characteristic approaches to mechanochromic polymers are introduced. In particular, mechanochromic elastomers utilizing polymer reactions based on dynamic covalent chemistry are described in detail. Diarylbibenzofuranone (DABBF), which can undergo homolytic cleavage of the central C-C bond by mechanical force to form relatively stable blue-colored radicals, was used as a mechanochromophore because the cleaved radicals could be evaluated quantitatively using electron paramagnetic resonance measurements. Well-defined linear and star polymers with a mechanochromophore functionality at the center of each polymer structure were designed to prepare mechanoresponsive materials with high sensitivity and demonstrate the relationship between polymer architecture and mechanoresponsiveness in the bulk state. Two types of mechanochromic elastomers were prepared; one is segmented polyurethanes and the other is polymer/silica nanocomposite elastomers. The segmented polyurethanes were synthesized by polyaddition, whereas the polymer/silica nanocomposite elastomers were prepared by sol-gel method. The mechanochromic properties of both elastomers are described.

Carbon nanotube (CNT) was found in 1991 by Dr. Iijima, and it has attracted wide attention because of its high mechanical properties along with high electrical and thermal conductivities. However, practical application of carbon nanotube has not been achieved yet. In this article, I repot promising applications of CNT and rubber composite such as high thermal conductive flexible sheet (TIM), stretchable electric wire for devices, high wear resistant material and high thermal durable materials for shielding field. Furthermore, I also report the importance of CNT dispersion for getting high performance the CNT and rubber composite. Just after the synthesis, CNTs form bundled structure. To derive the structural advantage of CNT for filler, de-bundling is important.

Styrenic thermoplastic elastomer (TPS) is styrene-butadiene block copolymers, widely recognized with excellent elastomeric characteristics, compatibility with polystyrene and other polymers. TPS is produced in combination with living anionic polymerization, chemical modification and hydrogenation. In this review, industrial production methods, properties and functions are reported.

Natural rubber (NR) is polyisoprene with 100% of cis-1,4 structure on main chain. NR is a natural resource derived from a tropical tree called Hevea brasiliensis (para rubber tree) that produces latex. NR is an industrial raw material, and global NR production and consumption are about 12 million ton per year (2014) which are about 40% in total rubber usage. Since NR shows superior physical properties such as break strength or durability comparing with synthetic rubber, NR demand is expected to rise in the future. In this review, we describe the present state, trend of new research and development of NR.

The mechanisms of rolling friction and the sliding friction under lubrication are explained. These phenomena of rolling friction were experienced in the friction of tires and ball bearings. The boundary lubrication, mixed lubrication, hydrodynamic lubrication and elastohydrodynamic lubrication were also discussed in this paper.