40—THE ENTHALPY AND SPECIFIC HEAT OF NYLON 6.6 YARN

Abstract

Experience indicates that the energy required to heat nylon 6.6 yarn containing a small percentage of moisture is much greater than might be expected from calculation from available specific-heat data. Previous specific-heat measurements have been made only on dry nylon, but an exact knowledge of the heat absorbed by yarn at normal regains is of obvious value in designing heating equipment for textile machinery. The work described in this paper sets out to measure, to an accuracy of 4%, the total heat absorbed by nylon 6.6 at normal regain when it is heated from room temperature to temperatures in the range 6O–220°C. The method of measurement employs a sensitive yarn-flow calorimeter, which is described. In heating a yarn to 220°C, about six times as much heat IS absorbed by yarn conditioned to normal regain at 65 ± 4% r.h and 20 ± 2°C as by dry yarn. Heating rate has no effect on heat absorption in the range 100–1000 degC sec⁻¹.