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In order to develop an eco-friendly method for silk reactive dyeing that uses a lower accelerant dosage to achieve a higher dye fixation, hexyl dimethyl octyl ammonium chloride was synthesised as an accelerant for the dyeing of silk with reactive dyes. The accelerating effect, corresponding adsorption kinetics, and interaction mechanisms among hexyl dimethyl octyl ammonium chloride, reactive dyes, and silk were investigated. At hexyl dimethyl octyl ammonium chloride concentrations of 10.8–14.4 mm, the dye fixations for three reactive dyes were much higher than those achieved with sodium sulfate, even though the required dosages of hexyl dimethyl octyl ammonium chloride were 30–40 times lower than those of sodium sulfate. The wash fastness, rub fastness, light fastness, K/S, and colour difference values after dyeing with hexyl dimethyl octyl ammonium chloride were similar to those obtained using sodium sulfate, and silk can be dyed uniformly. The adsorption kinetics followed a second-order kinetic model. The activation energies of surface adsorption for the three reactive dyes were lower than those of sodium sulfate. The high fixation of reactive dyestuffs and the low required dosage of hexyl dimethyl octyl ammonium chloride demonstrate that the use of this new accelerant provides a novel, highly efficient method for silk dyeing. A possible acceleration mechanism of hexyl dimethyl octyl ammonium chloride for reactive dyes adsorbed on the surface of silk was proposed, based on a series of activation parameters of the adsorption process.

Herein, polyimide/graphene sheets (PI/GS) nanocomposite films with different GS distribution structures have been successfully obtained by controlling the imidization degrees, and the effect of the lamellar structure on the properties of PI film has been investigated. The results show that GS are gradually parallel to the surface of PI nanocomposite film with the increase of the imidization temperature, and 150 °C is the critical temperature, where the imidization rate is the fastest and the lamellar structure begins to form. Furthermore, with the drying temperature increasing, the corresponding thermal, electrical and mechanical properties of PI/GS nanocomposite films are significantly improved compared with that of pure PI films, which are ascribed to both the higher imidization degree and the lamellar GS structure. It is noteworthy that the formation process of the lamellar structure at different imidization stages can be directly observed by scanning electron microscope. Based on these results, a model has been proposed to explain the relationship between the lamellar structure and properties of PI composite film under different imidization stages, and the confinement of the thickness may be the most important factor for the formation of lamellar GS structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43575.