¹H pulse NMR analysis of silane-treated layers on glass fiber surfaces

Abstract

The surface treatment of a glass fiber using mercapto-functional silane coupling agent having a di-or trialkoxy group has been studied. The surface of silane-treated fiber is observed by scanning electron microscopy. The treated layer looks hard like glass for the trialkoxy silane-treated, whereas it looks soft for the dialkoxy silane-treated. Molecular mobility of the treated layer is analyzed by 1 H pulse nuclear magnetic resonance spectroscopy. The amount of silane loading increases with increased silane concentration in the treatment solution. The relaxation time for the surface layer is longer for the dialkoxy structure than for the trialkoxy structure. The silane chain is flexible in the dialkoxy structure, but is rigid for the trialkoxy structure, independent of the loading amount of silane. The relaxation behavior for the mixture of the di-and trialkoxy structures is between those of the pure dialkoxy and trialkoxy structures and depends on the mixing ratio. The network density of silane chains on the glass fiber can be controlled by varying the mixing ratio of the di-and trialkoxy compounds. IntroductionThe effect of interfacial adhesion between inorganic fillers surface-treated with silane coupling agent and matrix polymer on the mechanical properties of the composites has been investigated [1-11]. A previous study described the surface treatment of spherical silica particles with mercapto-functional silane using di-and trialkoxy structures [8]. With multilayer coverage, hairy (linear chain) and network structures are expected to form on the surface by polycondensation reaction using di-and trialkoxy silanes, respectively. The molecular mobility of silane chain with such structures was investigated by pulse 1 H nuclear magnetic resonance spectroscopy (pulse NMR) [12][13][14]. The spin-spin (T 2 ) relaxation time obtained by measuring the free induction decay (FID) was longer for the dialkoxy structure than for the trialkoxy structure. The silane chain was flexible for the dialkoxy structure, whereas it was rigid for the trialkoxy structure.The treated silica particles were mixed with polyisoprene rubber (PIR) matrix and vulcanized, and the effects of loading amount and number of alkoxy groups in silane on the stress-strain curve of the filled PIR were investigated [6]. The stress at the same strain

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