Preparation and characterization of Kevlar nanofiber based composite phase change material with photo/electro-thermal conversion properties

To develop phase change material suitable for multi-energy complementary applications, nanofibrous Kevlar aerogel containing paraffin and then deposited with polypyrrole (PPY-KNF/PF) were fabricated. The structure, morphology and photo/electro-thermal conversion ability of PPY-KNF/PF, especially the effect of confinement on the latent heat storage capacity of composites without PPY (KNF/PF) were investigated. The results showed that PF was induced to the interface of nanofibers, then intercalated into the nanosheets during self-assembly of KNF and formed three-dimensional porous structure. The maximum latent heat of KNF/PF with PF fraction of 78.7 % is 117.2 J center dot g(-1) without leakage. Due to the confinement effect, the actual enthalpies of KNF/PF are all lower than the theoretical latent heats, and the difference between the actual and theoretical values enlarges with the increase of PF percentage. The deposition of PPY has no effect on the structure and morphology of KNF/PF and the PPY-KNF/PF80 displays good shape stability and high latent heat storage ability (101.9 J center dot g(-1)). Moreover, the composite was endowed with multi-properties of electrothermal and active photothermal conversion, which makes it more suitable for use in the case of insufficient solar energy. This work demonstrated an effective strategy to fabricate composite PCMs with electro/photo-thermal conversion devoting to energy conversion, storage and complementary utilization.