Regarding the bonding mechanism between metal and rubber, the detail has not yet been demonstrated. We have studied the changes of adhesive force in the proceeding of vulcanization reaction. And the results were as follows:- in the case of slow vulcanization rates, the adhesive force was proportional to compounded sulfer. But in the case of rapid vulcanization rates, a large amount of compounded sulfer was consumed for the vulcanization reaction, therefore the adhesive force was comparatively low. Also the increase rates of adhesive force per unit sulfer which corresponds to the increase rates of rubber strength was proportional to its rubber strength.
On the other hand, regarding the coating, a large difference of the adhesive force between copper and bronze coating was not recognized, and the adhesive force of brass coating by diffusion was considerably low.

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Oligomers (cyclic trimers and dimeric esters) of sulfur-containing aldehyde (SA) as thermal stabilizer were added to polypropylene and polyethylene oxide, and the thermal stabilizing effect of the oligomers was investigated by TGA and DTA. This effect was evaluated by measurement of the extent of shift on TGA and DTA thermogram. These samples had a similar effect to commercial dilauryl-thiodipropionate (DLTP), and a synergistic effect due to the addition of phenolic antioxidant was observed. The regular relationship between the chemical structure of SA oligomers and these thermal stabilizing effect could not be classified from this method. It was found that thermal analysis was one of the best estimative methods of thermal degradation. Furthermore, a homogeneous reaction of t-BuOOH with SA-oligomers in chloro benzene solution was carried out. In this case, the ability of SA-oligomers as peroxide decomposer was generally in the following order, SA-dimeric esters>SA-cyclic trimers_??_DLTP.

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Sulfur-containing aldehyde (SA) oligomers were added to vulcanized rubbers (isoprene rubber and pro pylene oxide rubber), and their thermal stabilizing effects were investigated by stress relaxation, thermal analysis, etc. Although the effect of SA oligomers was smaller than that of commercial phenolic and amine antioxidants, these oligomers had a similar effect to commercial dilaurylthiodipropionate as antioxidant of hydroperoxide decomposer type, and a synergistic effect due to the addition of phenolic antioxidant was observed. And thermal analysis was effective as one of the methods for estimation of thermal oxidative degradation.

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Naturally occuring non hem iron protein (NHIP) is characterized by containing a few iron atoms and the same number of labile sulfur atoms. In the course of our investigation on NHIP model compounds, we noticed that mechanisms of vulcanization and acceleration of rubbers with sulfur are probably similar to the behavior of labile sulfur in NHIP. We synthesized bis (perthiobenzoato) zinc I as a chelate containing labile sulfur and bis (dithiobenzoato) zinc II as the precursor to I. When these compouns were used as vulcanizing agent and accelerator of EPDM, we found that I is both an excellent vulcanizing agent and an excellent accelerator, and II is a superior accelerator.

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Relationships between stress-strain curves and the linear viscoelastic properties and also the dependence of viscosity on a shear rate were investigated using synthetic cis-1, 4-polyisoprene and natural rubber of which Mooney viscosities were from 28 to 70. In the comparison of the zero shear viscosities of both samples in the same Mooney viscosity region, natural rubber showed a higher value than synthetic cis-1, 4-polyisoprene, Stress-strain curves at -10°C to 70°C and under the strain rate, ε, between 1/9 and 1/900 sec^-1 were expressed bp the following equations for both samples;
S(t, ε)=(T/T₀)f(t)g(ε) and f(t)=(1/t)_??_^t₀E(t_i)dt_i
where S(t, ε) is stress, E(t) stress relaxation modulus, T absolute temperature, T₀ reference temperature and t=ε/ε. g(ε) of synthetic cis-1, 4-polyisoprene well coincided with that of natural rubber. It follows from this that synthetic cis-1, 4-polyisoprene has a lower weight-average molecular weight than natural rubber in the same Moonep viscositp region so that synthetic cis-1, 4-polyisoprene is apt to cold flow and shows a lower green strength than natural rubber.

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