High performance thin nonwovens for thermal insulation

Abstract

Thermal insulation material is a crucial component in multi-layer cold weather clothing because majority of the heat exchange from human body to atmosphere is controlled by insulation layer which are mostly fibrous materials or nonwovens. Nonwovens are potential candidate for insulation applications because of their unique fibre orientations with interconnected voids and porous in nature which restrict heat loss from body. In most cases, high dense lofty or fluffy nonwovens are required to achieve maximum insulative performance. But these nonwovens have numerous drawbacks due to thicker in nature such as poor structure stability, compression recovery and washing resistance, less durable, expensive, and uncomfortable. So, development of high-performance thin thermal insulation materials is essential to increase comfort, structural stability, and compression recovery, and to decrease the cost, and complexity. Hence, in this work, an effort had been made to create thin and light weight nonwovens with high thermal insulation performance. Nonwovens with thickness of about 8 mm and areal density of 100 gsm were developed using different types of advanced functional fibres (Aerogel fibres, PODRUN, dope dyed black fibres, FIR fibres, silica fibres, IR absorber, micro-fibres, graphene incorporated polypropylene fibres) with different blend ratio (10%, 20% & 40%) along with polyester microfibres and bonding fibres. This study investigated the thermal insulation properties based on different types of functional fibres and their blend ratio in nonwoven paddings. The nonwovens physical properties (thickness and density), mechanical properties (stiffness) and functional properties (air permeability) were also studied and analyzed on the influence on thermal performance. The thermal insulation (Clo) properties of every set of nonwovens with different functional fibres were determined and reported. This study had also made comparative study of developed nonwovens with different functional fibres against other commercially available similar insulation materials. The results suggested that all thin nonwoven developed using functional fibres possessed extremely efficient thermal insulating properties with Clo ranging from 1.53 to 2.06 for 100gsm and 8 mm thickness. The results also revealed that the types of functional fibres and blend ratio have significant influence on thermal insulation performance of resultant thin nonwovens. The developed high-performance thin nonwovens with 100 gsm and less than 8 mm thickness have significantly higher thermal insulation values than commercial most successful thin nonwovens such as ThinsulateTM (Type C & U) and HEAT-MXTM. The present study is significant in providing a novel thin nonwoven with high thermal insulation as a middle for the various applications such as cold wear outdoor clothes, work gloves, sleeping bags, boots, and shoes etc.