NIPPON GOMU KYOKAISHI

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SBR vulcanization with MBTS•S formulation was found to be inhibited by addition of 5-10phr powdered copper. A similar inhibiting behaviour was observed in SBR vulcanization with CBS•S or TMTD formulation. Such an inhibiting activity was also detected with copper compounds. The activity increased in order of copper dibutyldithiocarbamate_??_CuO<Cu₂O, CuS<Cu(Aco)₂<CuCl₂<cupric stearate_??_Cu. An inhibiting activity of usual powdered metals for vulcanization increased in order of Pb<Fe, Ni, Cr, Co, Mn< Sb, Al<Zn_??_Cu, Hg. The inhibiting activity of copper for SBR vulcanization was found to diminish with addition of nitrogen-containing organic thiol compounds such as zinc-dibutyl-dithiocarbamate, 2-mercaptobenzothiazole (MBT), 6-dibutylamino-1, 3, 5-triazine-2, 4-dithiol or trithiocyanuric acid (TTCA). TTCA which is trithiol was most effective. Thiol groups of TTCA react readily with copper to form a deactivated chelating compound as well as with SBR in presence of MBTS in the vulcanizing compound. Such a coupling effect between copper and SBR was hardly observed with monothiol compounds such as MBT. Thus, a composite of vulcanized SBR and powdered copper with an excellent mechanical property was obtained through the following composition: SBR 100, powdered copper 100, HAF 50, ZnO 5, S 0.5, TTCA 6, MBTS 6.6, antioxidant D 2phr.

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The object of this report is to introduce an automatic measurement technique for tensile tests by using a television camera to measure marking-to-marking distance for dumbbell-shapped specimens at a position away from the specimen.
Especially, this system is effective for visco-elastic materials, represented by rubbers which extend up to five to ten times until fracture.
The most significant feature of this system is the transformation of the positions of the markers on a specimen into digital data by utilizing area scanning of a TV camera. This system distinguishes bright markings from the dark surface of a specimen, and use the digital gate technique which enables selecting the data relating to the specimen without being affected by obstructions which come in sight of the TV camera.
This technique not only enables automatic tensile tests or creep tests in an oven and permits appilcation to stress relief tests and low stretch stress tests but also improves the accuracy and reproducibility of measurements with labor saving effect.

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