Optimization of Warmth Retention in Nonwoven Materials Made from Coarse and Semi-Coarse Sheep Wool

This study aims to examine the influence of parameters such as the number of layers, needle-punching frequency, and fiber content percentage on the warmth retention properties of nonwoven materials. Nonwovens were produced using a needle-punching method from coarse and semi-coarse wool fibers of the Kazakh sheep breed. The Response Surface Methodology (RSM) was used to determine the combination of sample parameters that achieved the highest warmth retention. A full factorial design was utilized to describe the relationship between the factors and the resultant thermal properties, based on which a mathematical model was developed. Additionally, the breaking strength and air permeability of the samples were measured. The experimental results indicated that the sample thickness, which increases with the number of layers, had the most significant influence. Another important factor was the frequency of needle punching, which determined the degree of entanglement of the fibers. The variation in the proportion of coarse and semi-coarse wool fibers exhibited a negligible effect. Thus, it was determined that the combination of four layers, a needle-punching frequency of 600 spm, and 60% coarse wool exhibited the highest warmth retention. This sample also demonstrated favorable mechanical strength and air permeability characteristics.