Preparation And Properties Of Composite Phase Change Materials Of Fatty Alcohol

Organic solid-liquid phase change materials have been widely studied due to the high energy-storage density without undercooling and phase separation in terms of thermal energy storage.At present,related studies mainly concentrates on solving flowing problem of PCMs after phase transition,improving thermal conductivity of organic phase change system,and endowing with specific energy conversion functions.Based on high enthalpy value and adjusted phase change temperature of long chain fatty alcohols,composite phase change system with thermochromic property was obtained by introducing thermosensitive dyes.Coaxial electrospinning,as a encapsulation technology to thermochromic phase change system or fatty alcohol respectively,was introduced to prepare novel core-shell PCMs with thermochromic and color performance,endowing the materials with shape-stability.Three composite PCMs with reversible thermochromic property: TC-DD,TC-TD and TC-HD were prepared by combining n-dodecanol,n-tetradecanol and n-hexadecanol with thermosensitive black ODB-2 and bisphenol A,respectively.The materials showed good thermochromic property and high enthalpy(more over 170 J/g).Furthermore,TC-HDs with different proportions were prepared by using n-hexadecanol as raw material and controlling the ratio of ODB-2 and bisphenol A.The materials showed excellent performance of reversible discoloration driven by visible light,which are black before the phase change with ability of visible light absorption and photo-thermal conversion,and become colorless after phase change nonetheless.By this time,the light absorption ability is weakened,and photo-thermal conversion is blocked,so temperature control is achieved.Reversible thermochromic material TC(TF-G)-DD was prepared using n-dodecanol(with high solubility),bisphenol A and fluorane thermosensitive dye-thermosensitive green TF-G as raw materials.Furthermore PAN-TC-DDs were prepared via coaxial electrospinning technology with polyacrylonitrile(PAN)as a shell,TC(TF-G)-DD as a core.Phase change energy-storing fiber of core-shell structure formed with TC(TF-G)-DD encapsulated in PAN which endows PAN-TC-DDs with excellent stability in shape.And TC(TF-G)-DD endows the material with thermochromic performance.Therefore,PAN-TC-DDs exhibited excellent thermochromic function and thermal capacity,when encapsulation rate reaches 85.5%,the melting enthalpy is around 110 J/g.Blue energy-storage fiber mat PET-DD was prepared in situ by coaxial electrospinning with polyethylene terephthalate(PET)as shell and n-dodecanol as core.Encapsulation rate of n-dodecanol increases with sampling rate of core spinning solution,and so does phase change enthalpy.When the content of n-dodecanol is 61.3wt %,its melting enthalpy can reach 87 J/g.PET-DD exhibited good thermal and mechanical properties.Compared with pure PET fiber,the tensile strength of PET-DD decreases owing to encapsulation of n-dodecanol,its still reaches more than 3 MPa.Moreover,phase change fiber showed outstanding shape stability and thermal cycling stability.