Investigations on Kapok/Polypropylene Needle Punched Nonwoven for Thermal Resistance Applications

This paper describes a study of a nonwoven sample constructed of kapok/polypropylene used as a thermal insulation layer in cold weather. The needle punching technique was used to create three nonwoven fabrics with varying kapok/polypropylene blend ratios of 70/30, 60/40, and 50/50 and characterized for thermal insulation application. Considering higher thermal insulation of 70/30 blend ratio, further experimental designs were created by changing punch density, depth of penetration, and web areal density in the 70/30 blend ratio. The structural features of kapok fiber and the cohesiveness of nonwoven fabric are demonstrated using SEM analysis. The effect of web areal density and machine parameters on thermal insulation of nonwoven was investigated. Nonwoven fabric characteristics such as thickness, air permeability, porosity, and bulk density were also investigated. Thermal resistance increases with increase in depth of penetration and 12.5 mm showed higher thermal resistance and decreased with higher punch density. The higher number of layering of the optimized sample number 2 showed a higher thermal resistance value of 0.5272°C m2/W.