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Pulsed NMR study on the silica‐filled rubber systems

1985; Wiley; Volume: 30; Issue: 8 Linguagem: Inglês

10.1002/app.1985.070300829

1097-4628

Masayoshi Ito, Takehusa Nakamura, Koji Tanaka,

NMR spectroscopy and applications

Abstract Proton spin–spin relaxation time has been measured by the pulsed NMR technique for the bound rubbers extracted from both silica‐filled polyisoprene and polybutadiene composites. Two relaxation times T 2 t (short) and T 2 l (long) are observed for all samples. They are ascribed, respectively, to the relaxation of the tightly and loosely bound rubber components. When the silica filled polybutadiene composite is heat treated at 120°C, loosely bound rubber is preferentially formed, which leads to the increase in the total bound rubber fraction in the composite. During the heat treatment of silica‐filled polyisoprene composite, a part of the loosely bound rubber phase is transformed into tightly one, and simultaneously the chain mobilities of both phases become more constrained state. These changes are accompanied by the degradation of polyisoprene molecules probably due to the strong chemical interaction of silanol group and rubber molecules. At a prolonged heat treatment, the fraction of total bound rubber in the composite decreases as a result of the degradation of the loosely bound rubber molecules.