Thermal Behavior of Silica Xerogel and Graphene Incorporated Composite Nonwovens

In this study, single, 2- and 3-layered composite polyethylene terephthalate (PET) nonwovens containing SiO₂ xerogel and/or graphene were fabricated. In the first step, the xerogel-containing composites were prepared by either in situ SiO₂ xerogel embedding in the nonwoven or electrospinning SiO₂ xerogel-containing recycled PET (rPET) nanofibers on the nonwoven. Following, a graphene-containing electrospun rPET nanofibrous layer was constructed on both SiO₂ xerogel incorporated composite nonwovens and neat nonwoven. The resultant layered composites were morphologically, spectrally, and thermally characterized using SEM, EDX, FTIR, and TGA. The thermal behavior of the composite structures was particularly investigated via analyzing their thermal comfort properties and infrared thermal images. It was observed that the best improvement in the insulating property of the nonwoven was reached when only SiO₂ xerogel was in situ embedded in the nonwoven, possessing a thermal conductivity coefficient of 32.65 mW/m^.K, lower than 43.45 mW/m^.K of bare nonwoven. Contrarily, the thermal conductivity coefficient of the composites improved the most when the nonwoven was covered only with graphene-loaded nanofibers, reaching 48.82 mW/m^.K, while composites containing both SiO₂ xerogel and graphene layers showed thermophysical properties in between with thermal conductivity coefficients of 37.05–41.20 mW/m^.K. The resultant composite nonwovens are encouraging materials for use in thermal management applications.