Analysis of states of water in cashmere fibers and utilizing water as molecular probe for pore size distribution

Abstract

Fundamental understanding of cashmere–water interaction is a critical part both for the manufacturing of cashmere processing and the development of cashmere-based heat-moisture management textiles. Based on the unfreezable threshold and hygroscopic properties, different types of water in cashmere and the interaction between water and fibers were investigated by using low-temperature differential scanning calorimetry (DSC) and dynamic water vapor sorption (DVS), the pore size distribution in cashmere were also determined according to the Gibbs−Thomson effect of the bound water probe. The amount of free water and non-freezable water was experimentally detected, and the critical moisture regain of these two types of water was 37.2%. The pore size distribution of cashmere showed that most pores were less than 60 nm in diameter. The monolayer moisture content of cashmere accounted for up to 17.26% (corresponding to 50 °C) of the non-freezable water, which were evaluated though the Brunner–Emmet–Teller (BET) theory. The net isometric heat of desorption is calculated from the partially overlapping isotherms at different temperatures, which break through the limitation of the Clausius–Clapeyron equation, and the boundary of monolayer water and multilayer water were identified by the curve of isosteric heat.