Fabrication of a nanofibrous sheet using electrospinning technique incorporating mixture of fatty acids (stearic and lauric acid (LASA)) and polyvinyl alcohol was reported. PVA acted like a guiding polymer for electrospinning forming the fibrous matrix and fatty acids role was that of a phase change material. It was demonstrated that these sheets can act like flexible thermoregulating enclosures. A significant drop in eutectic temperature in the fatty acid binary mixtures was observed when in nanofibrous mats as compared to their bulk mixtures. However, the nanofibrous sheets incorporating the eutectic composition showed poor mechanical strength. In this work, we incorporate PDMS (polydimethylsiloxane) as additional component in the spinning solution which imparts improved mechanical strength to these sheets. Here we have studied pure stearic acid in PVA-PDMS nanofibrous sheets and thermal, mechanical, and morphological characacterizations of these composite sheets have been performed using DMA, tensile tests, differential scanning calorimetry, surface profilometry, and SEM. It was observed that mechanical strength improves by incorporating PDMS but only up to an optimal concentration. This result has been attributed to the ability of the stearic acid molecules to mediate binding between the PVA and PDMS long chain molecules via van-der-Waals bonding. Modeling of the mixtures suggested that the drop in eutectic temperature in the fatty acids binary mixtures may be attributed to a constrained environment of hydrophilic nature (due to PVA) experienced by the fatty acid mixtures which alters the molecular interactions between the two components. Incorporating PDMS will also serve to test this conjecture as it will reduce the hydrophilicity in the fibrous environment. To this end, measurements on hydrophilicity and oleophilicity of the surfaces of the sheets using contact angle measurements will also be presented. The phase behavior of the binary mixtures of the fatty acids (LASA) have been studied in the PVA-PDMS nanofibrous matrix.

PDMS incorporated PVA-PCM electrospun nanocomposite fibrous mats with improved mechanical behavior for membrane and heat storage applications

256th National Meeting (2018)

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