NIPPON GOMU KYOKAISHI

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Ibaraki university developed the novel neutron microscope on the instrument iMATERIA at MLF of J-PARC, which was originally a powder diffractometer, recently reinforced by detecting small-angle scattering. The method of dynamic nuclear polarization (DNP) for protons was combined with small angle neutron scattering (SANS)(DNP-SANS). In a long course of history of DNP, our activity is the world's first challenge to incorporate DNP-SANS for routine industry uses. This “neutron microscope" provides us multiple reciprocal space images by changing scattering lengths of proton, in turn by varying “contrast" of individual scattering components. Conventionally, for the contrast variation, chemical treatments are required to substitute protons with deuterons. The DNP approach is suitable for industry application (for example to observe tire rubbers), because we do not need highly-specialized deuterium substitution. In this article, we describe theoretical background of DNP including scattering functions and the experimental of 7T super-conductive magnet, NMR to evaluate proton spin polarization, and microwave to change polarization. The sample preparation to dope radicals into sample specimens are necessary. We review the studies on homopolymers of polystyrene and polyethylene, poly (styrene-b-isoprene) diblock copolymer, and vulcanized SBR rubber.

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It has long been known that mold pollution occurs in all rubber materials and their unvulcanized rubber compounds during mold vulcanization molding. As the mold vulcanization process is repeated, the pollutants adhere to the mold surface, accumulate, solidify, and increase the amount of pollution, which in turn causes mold pollution, delinquent of mold release, molded product shape defects, and difficulty in cleaning and automating the mold for reuse. The factors that cause these problems include rubber materials, rubber compounding agents, and the manufacturing of rubber products. Since the rubber materials, vulcanization systems, and rubber compounding agents used in rubber products are all different, the behavior and pollutants during mold vulcanization molding are different, making it difficult to develop various methods to prevent or reduce mold pollution. As a method that does not affect the properties and functions of the molded product, the selection of metal materials for the mold, surface treatment of the mold, and the blending of mold pollution inhibitors are being considered.

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