The reactive aluminum carboxylates were prepared by the reaction of aluminum chloride with sodium carboxylate having an amino or a hydroxyl group in its molecule. The structures of these prepared aluminum compounds may be shown as the following general formula and their average particle sizes of them are in the range of 0.5-1.5×10μm.
(X-R-C =O-O-)₂Al-OH R=(-CH₂-)_n or _??_, X=-NH₂ or -OH
From the results of the compounding test for NBR, a good dispersity for NBR pure gum stocks was obtained and remarkably improved the tensile properties of vulcanizates, compared with those of a control sample. In particular, the reinforcing effects of aluminum amino-benzoate (ABA-Al) was superior to those of the other aluminum derivatives.
From the results of the analyses of the Mooney-Rivlin plots, it was recognized that C₁ and C₂ term increased with inceasing the amount of p-ABA-Al. It seems that the reinforcing effects may result in the pseudo crosslinking between NBR and the aluminum compounds.

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An unstrained rubber is isotropic in its optical, however, it becomes birefrigent, as can be readily demonstrated by stretching a film of vulcanized rubber between crossed polaroid plates. On release of the stress it reverts to optically isotropic state.
In the testing the tensile strength of rubber useing the dumb-bell shape, measured photoelastic number to stress-strain relationships, we gained formulae (1) and (2).
σ/n/t=f/λ……(1)
ε/n/t=f/E_R……(2)
where σ: stress, ε: strain, λ: elongation ratio λ=1+ε, t: thickness of rubber, f: photoelastic constant,
n: photoelastic number
E_R and ν_R from this study seriess report No. 1.
E_R=2G(1+ν_R) E_R; Rubber-like Young′s modulus
ν_R=1-1/√<λ>/λ-1 ν_R; Rubber-like Poisson′s ratio

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As an approach to the material mechanics for amorphous chain polymers over wide range of temperature including softening or hardening ones, a constitutive equation representing glass-rubber transition with temperature is obtained in terms of combining a model of transition from rubbery to btittle with the constitutive equation proposed in a previous paper. The model of transition is proposed without essential consideration of the complex molecular processes of the glass transition, that is the glass transition phenomenon is treated as a simple equilibrium one. A “two elements model” composed of chains in the rubbery state and in the glassy state is employed and the ratio between the densities of the rubbery chain and the glassy chain at a temperature is assumed to be determined from the ratio between the canonical ensemble sum-over states for the two kinds of the chains and the acceleration factor for cooperative phenomena.
It is shown that the constitutive equation possibly represents rapid change in stress-strain relation according to variation of temperature through a transition zone.

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