AbstractMolecular motion in cured epoxy resin filled with mica flakes was investigated by dynamic mechanical and broad‐line nuclear magnetic resonance measurements. Temperature dependences of dynamic modulus and tanδ were determined at 10 Hz for samples containing various amounts of filler. A primary dispersion temperature,T∞, corresponding to the glass transition, shifts to higher temperature with increasing filler volume fractionVf. The magnitudes of the slope parametersHr(representing storage modulusE′ data belowTg) decreased with increasingVf, butHg(representingE′ data belowTg) remained nearly constant over the whole loading range studied here. NMR line shapes were observed over the temperature range from room temperature to about 200°C for unfilled and filled samples. Each sample showed a distorted line shape in the transition region where major narrowing occurs. The distorted line shape was decomposed into both broad and narrow components by Gaussian analysis. The temperature range where both components can be obtained becomes broader with increasing filler content. The possibility is set forth that the filler immobilizes the chain segments and causes a different distribution of local mobility around the junct
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