The use of cushioned insoles has been recommended as a method to reduce the impact forces on feet associated with running. This study is used to determine the influence of insole structure and thickness on the permeability and conductivity properties of air and temperature. The insoles are constructed with warp-knitted polyester spacer fabrics with 3D construction and have good cushioning, permeability, and conductivity properties. The middle layer is made up of polyester monofilament yarn which decides the thickness of fabric, and the two outer surfaces of the fabric were made from polyester multifilament yarns which is a closed and open structure. The comfort properties of spacer fabric have been studied by measuring air permeability, water vapor permeability, and thermal properties with respect to fabric porosity. One-way analysis of variance is used to analyze the significant of fabric thickness and surface structures. The experimental result shows that the vertical gap of the two outer surface layers and the horizontal pore size of the face surface decide the permeability and conductivity properties of spacer fabrics. The fabric with higher porosity show high permeability of air and water vapor. Depending on the fabric thickness and structure, the 4-mm thickness of spacer fabric with locknit structure resulted in low air and water vapor permeability. It is found that the 3.1-mm thickness spacer fabric with hexagonal net structure proves to have good air and water vapor permeability and comparatively lower thermal conductivity.

Linear density of filament, fabric structure, and number of loops per unit area are the major factors which influence the porosity of warp knitted spacer fabrics. The characteristics of air and water permeability of textile fabrics are chiefly influenced by the porosity of the fabric. An attempt has been made to analyze the water vapor permeability of warp knitted polyester spacer fabric. Spacer fabric face and back surface layers are constructed by polyester multifilament and the middle layer is connected to the two surface layers by polyester monofilament. The behavior of porosity and water vapor permeability were analyzed with respect to the linear density of polyester. The experimental result indicates that the water vapor permeability is highly influenced by porosity of a fabric. The statistical analysis proves the degree of correlation between polyester linear density of spacer fabric layers and their responses. The face and middle layers of fabric are highly significant with the porosity and water vapor permeability. Box-Behnken model was adopted for optimization and a better R 2 value of 96.5% is achieved in porosity and the water vapor permeability is 92%.