The Thermal Insulation Properties of Spacer Fabrics with a Mechanically Integrated Wool Fiber Surface

In relation to the engineering of compression resistant thermal insulation materials, an unconventional application of hydroentangling technology is introduced in which, lightweight, wool webs are mechanically attached to one side of preformed knitted spacer fabrics to partially occlude the underlying apertures. In contrast to conventional homogeneous fabrics, the resulting hydroentangled wool fiber web-spacer fabric constructs have markedly reduced thermal conductivity while there is little change in the overall fabric density; this is attributed to increased air entrapment within the cross-section of the spacer fabric due to the occlusion of the large apertures in the surface. Basic underlying theoretical principles are reviewed in relation to heat transfer in fibrous materials.