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Impact of excess silane on viscoelastic properties of epoxy

Impact of excess silane on viscoelastic properties of epoxy.

Libin Kaleeluvilayil Babu

Mechanical & Aerospace Engineering

This study investigates the influence of excess organofunctional silane on the elastic and viscoelastic properties of epoxy resin system under hygrothermal conditions. Such silanes are used in fiber surface treatments. It is hypothesized that the presence of excess silane within the matrix can degrade its properties. Samples are prepared by adding (3 glycidyloxypropyl) trimethoxysilane (GPTMS) in wt. percentages from 0 to 8 to DGEBF epoxy which is cured using an amine based hardener and subsequently subjected to water degradation at 21 degree C and 50 degree C. Gravimetric measurements for 48 hours are conducted to mon- itor the moisture absorption of the samples. Nanoindentation is used to characterize the variations in mechanical properties under impact of silane loading and change in environments. Elastic modulus and creep resistance data indicate that the addition of silane degrades the mechanical properties of epoxy resin. Glass transition temperature (Tg) is lowered by addition of silane and influence of hygrothermal degradation temperature. Fourier transform infrared spectroscopy (FTIR) of the non-degraded and hygrothermally degraded samples showed no substantial chemical change indicating that silane is well consumed in epoxy resin. It is found that presence of silane along with moisture in the environment affects the response of the epoxy resin system.