In this study, we discussed the canges of physical values (mobility of rubber molecular chain, weak physical bonds by interaction between structures, modulus and its thremodynamic properties and heterogeneous structures) in carbon black filled NR vulcanizates that is caused through three-dimensionally step-stressed fatigue (by combination of arbitrary stress σ_i, arbitrary times _??_t_ij, arbitrary temperature T_i) and constant stressed fatigue (basic stress σ₀, basic temperature T₀=a_i•T_i).
As a result, we inferred that linear additivity can be applicable against these physical
values and fatigue time in step-stressed fatigue can change into fatigue time in cnostant
stressed fatigue t(σ₀) by following equation:
t(σ₀)=∑i[∑jexp{(1-a_i)U₀-α(σ²₀-a_i•σ²_i)/kT₀}•_??_t_ij]
where k is Boltzmann's constant, α is transformation parameter, U₀ is activation energy, i is
level of stress and j is the number which passed stress level i.

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The vulcanization curves of SBR with various vulcanizing agents were obtained with an oscillating die vulcanometer. The relations between torque and time were analyzed by the three theoretical equations derived from our concept of vulcanization.
Experimental results could be explained well by our concept for the vulcanization of SBR with various accelerators-sulfur and mostly with zinc oxide-tetramethylthiuram disulfide or peroxide curing systems. Accordingly, it was suggested that the vulcanization of rubbers involved the following three stages; (A) the increased of the molecular weight by a coupling reaction of rubber molecules, (B) the formation of a network structure, and (C) the retarded vulcanization in a gel. Moreover, the kinetics of vulcanization was carried out from these analytical results.

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It is well known that rubber compound is reinforced by carbon black, and that the reinforcement is regarded as a result of the interaction between rubber and carbon black. In order to estimate the degree of interaction, we developed a new method, that is, after swelling a compound in solvent, the mixture of the compound and solvent is stirred at a certain rate, and the amount of rubber which can not be extracted from the compound by the solvent is measured.
The curve obtained by plotting the unextractable rubber against the various rates of stirring seems to be divided into three regions: (I) the region in which the amount of unextractable rubber decreases with increase of stirring rate, (II) the region in which the amount of unextractable rubber scarcely depends on the rate of stirring, and (III) the region in which the amount of unextractable rubber decreases again with increase of stirring rate. According to one of the experimental results, the amount of unextractable rubber in region II linearly increases with the apparent density of the compound. This fact suggests that the unextractable rubber in region II is strongly related to the amount of rubber absorbed to the surface of carbon black. Then, there is a critical stirring rate at the boundary between the regions II and III, where the polymer chains of rubber seems to be separated from the surface of carbon black because of the shear caused by the stirring. So the critical stirring rate seems to represent the strength of the interaction between rubber and carbon black.

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Pyrolysis-gas-chromatography equipped with a Curie-point type pyrolyzer and a fused silica capillary column is useful to identify composition of rubbers and other polymers. Efficient analytical conditions were investigated. Characteristic high-resolution pyrograms was obtained on a fused silica capillary column (25m×0.25mm i.d.) bonded with Silicone OV-1701. These results showed that it was possible to distinguish commercial rubbers and other polymers such as plastics, fibers, tackifiers and other high molecular weight materials one from the other.

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When fluorinated rubber (FR) vulcanizates came into contact with metal plates under a pressure, very high fixing strength arose between both. The fixing strength at an initial period is the result that hydrogen bonds arose in the interface between fluorine atoms on the vulcanizates and the metal surfaces. In subsequent fixing, a chemical reaction occurs in the interface to give a first order bond between both. As a result, the fixing strength increased with increasing the contact time. The interfacial reaction occurs mainly between active double bonds and/or active functional groups on the vulcanizates and a OH group on the metal surface: The active double bonds are produced on a backbone of polymers during vulcanization for FR with vinylidene fluoride unit. the active functional groups result from curing agents during vulcanization. In order to prevent the fixing between FR vulcanizates and metals, the surface of FR vulcanizates was modified by using the blooming method and a surface treatment technique. The immersing treatment of FR vulcanizates into the acetone solution of a reactive silicon and hydrogen hexachloroplatinate was especially very effective for preventing the fixing. This is for that the reactive silicon react with the active double bond and the active side chains on FR vulcanizates and the formed siloxane film has low surface tension for its polar components and prevents perfectly the above interfacial reactions.

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