Flammability and Thermal Degradation Behaviour of Wool/Polyamide 6.6 Blends

Abstract

Wool (WO) is often blended with polyamide 6.6(PA) at certain ratios in order to obtain fabrics with superior comfort and mechanical features. This type of wool rich upholstery fabrics are commonly preferred in aircraft seats. Flammability is an important characteristic of aircraft materials in terms of safety and regulatory purposes and it is highly dependent on the composition of blends. Since WO/PA blended fabrics cannot meet the flammability requirements, they are used in aircraft after flame retardant finishing. Needs for innovative new flame retardant chemicals for wool and wool blended fabrics are continuing. This study aims to present a comprehensive investigation and understanding of the fire and thermal degradation behaviour of 100% WO and wool rich blends (88.6% WO/11.4% PA and 78.5% WO/21.5% PA). The data obtained in this work can be used to identify the effect of polyamide 6.6 on the flammability of the wool and to develop new flame retardant chemicals for WO/PA blended fabrics. According to the results, the peak of heat release rate of 100% WO increased about 25% when blended with 21.5% PA as measured by the cone calorimeter and decreased about 12% as measured by the micro-scale combustion calorimeter. This is because the decomposition steps of the two materials are different. Regardless of the equipment used for measurements, the total heat release during combustion increased with the increasing PA ratios in blends. The thermal analyses were performed to study various stages occurred during thermo-oxidative decomposition of wool and its blends. The thermal degradation of PA could be observed as a separate stage during decomposition. On the other hand, the kinetics of thermal decomposition, even during the early stages of decomposition was modified for the blended fabrics. The results will contribute to the understanding of the effect of polyamide ratio on the flammability of the wool.