Application of composite polymeric textiles for the enhancement of thermal comfort

The evolution of technology, nowadays, is based on the development of new materials with unconventional combination of properties. Polymers are classified as electrical and thermal insulating materials. However, thermally and electrically conductive composite polymers could be used in order to enhance thermal comfort properties. To enhance the conductive properties of polymers, several approaches have been reported in literature. The ones tested in this thesis consist in the incorporation of graphene nano platelets (GNP) as conductive filler and metal coating of fibers. Graphene was chosen due to the extremely high thermal and electrical conductivity, coupled with low density, nano-metric scale, and outstanding mechanical properties. Conversely, nickel coating was chosen for his high conductivity and low oxidation properties. During the present thesis work, particular attention was devoted to the design and optimization of a device that simulates the thermal behavior of an athlete's forearm under effort. Using this apparatus, thermal conductivity and thermal dissipation of polyurethane-GNP membranes were experimentally compared with pristine PU membranes. A second set-up was built in order to test the electro-heating of Ni-coated textiles. These fabrics were tested with distinct imposed currents in different insulation conditions. Conductive properties of all the studied materials were investigated; moreover, they were also characterized by means of chemical-physical characterization (SEM, XRD, TEM) and thermal imaging The aim of this work is to test polymeric composite textiles to enhance thermal comfort of the user both under aerobic efforts and in extremely cold environments. Results showed that the addition of 5% wt. of GNP in the PU membrane, leaded to an improvement of dissipated heat of about 14%, whereas a GNP addition of 10% enhanced the heat dissipation of about 36%. Ni-coated textiles showed remarkable electro-heating results: when thermally insulated, with the imposition of 2 A of current, a ∆T of about 17 °C above room temperature is reported. Without insulation, with 5 A of current, the reached ∆T is 36 °C. Future work could consist in the design and production of prototypes, which allow to integrate these composite polymeric materials into garments.