NIPPON GOMU KYOKAISHI

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Anti-degradant efficiency of benzylamino derivatives as non-staining anti-ozonant and aminomethylphenol derivatives as anti-ozonant and anti-oxidant was estimated by the priventive rate of viscocity decrease of polyisoprene-chloroform solution and ozone cracking resistance effect on SBR compounds.
The results were obtained that substituted benzylamino derivatives that contained the N atom on substituent had remarkable anti-ozonant efficiency, and its efficiency was elevated by increasing the N atom on substituent.
Besides, anti-ozonant efficiency of aminomethylphenol derivatives gave the following results (1)-(3).
(1) p-Aminomethylphenol was more effective than o-aminomethylphenol.
(2) The efficiency was elevated as increasing the number of aminomethyl group.
(3) The order of the efficiency of aminomethyl group was -NMe<-NEt<-NC₃H₆OMe<-NC₃H₆ NMe, and it was found that the N atom on substituent was effective to reaction with ozone.
Anti-oxidant efficiency of aminomethylphenol was effective only p-aminomethylphenol. As o-aminomethylphenol formed the intramoleculer hydrogen bond of six membered ring, it seemed that the OH group and N atom were deactivated.
In order to clarify the reaction mechanism of N-substituted alkyl group with ozone, N, N-dimethylbenzylamine was used as model compound, and the reaction products were isolated and identified. It was found that the main products of ozonisation were N-methyl-N-benzylformamide and benzaldehyde.

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Mill blends of various styrene-butadiene random copolymer rubbers on today′s market (styrene content: 23.5-46wt%) and styrene-butadiene-styrene block copolymer (styrene content: ca. 25wt%) were studied. Hardness and compression modulus of uncured blends were measured and the shapes of curves of blend ratio dependence of physical properties and the state of dispersion polymers were paid attention to.
And it was found that this blend system is clearly a microheterogeneous blend system but that the zone sizes of dispersed polymers are small and the curves of hardness and compression modulus (in logarithm) against blend ratio are almost linear. And it was also found that the softening phenomenon after remilling (the roll surface temperature: 60°C) is hardly observed.
And further consideration leads us to presume a strong mutual interaction between polymers to be responsible for this phenomenon.

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Uncured blends of ethylene-propylene rubber and styrene-butadiene-styrene block copolymer (styrene content: ca. 25%), prepared by mill blend, were studied by measuring hardness and compression modulus, putting emphasis on the change of physical properties against blend ratio and the state of dispersion polymers.
And the hardness and compression modulus were found to change in “S” skaped curves against blend ratio. In the transition region of mixing states, the softening phenomenon by remilling (the roll surface tempemture: ca. 60°C) was observed and it was found that a rigid continuous phase of styrene-butadiene-styrene block copolymer is formed.
This seems to indicate that there is not a strong interaction between ethylene-propylene rubber and blocks which constitute styrene-butadiene-styrene block copolymer and block copolymer behaves like homopolymer and a microheterogeneous blend system is formed.
This consideration was further confirmed by a microscopic observation of the blend where a micro-heterogeneous mixing state was observed.

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