Preparation Of Solid-Solid Phase Change Material By Homogeneously Grafting Waste Cotton Cellu-lose With Polyethylene Glycol

Nowadays, resources and energy problems have restricted the economic development of various countries in the world more and more seriously, how to use the renewable resources of the nature to solve the problem of energy shortage which has gradually become research hotspot. Cotton cellulose was used as matrix and polyethylene glycol (PEG) as phase change medium, PEG was grafted on the cellulose macromolecular skeleton with polymerizetion methods to prepare solid-solid phase change materials, which not only makes full of the most abundant renewable resources of the natural, but also solves the problem that when phase change, solid PEG become liquid PEG, the deformation of the material is great and the use of the material is restricted, which has profound significance for environmental protection, realizing renewable utilization of resources and solving the problem of resources scarcity and energy shortage.In this study, waste cotton cellulose was used as raw materials, and was pretreated with alkali solution (NaOH solution), then was dissolved in lithium chloride/N、N-dimethylaceta-mide(LiCl/DMAc) system to obtain homogeneous cellulose; Phase material PEG was grafted on cellulose with the chain extender in this cellulose solution to obtain the solid-solid phase materials with side chains, In this paper, the alkali activated treatment process of cellulose and the dissolution process of the pretreated cellulose was investigated; the structure of the grafted products was studied by IR test; the heat preservation property and phase change characteristics of the products were studied by heat preservation test and DSC test; the thermal stability of the products was studied by TGA test; phase transition form of the products was observed by optical microscope.The results show that:After alkali treatment, Crystal structure changes of cellulose changed very obviously, crystallinity and crystal size also changed, and changed very obviously with NaOH concentration, but the Pretreatment temperature and time have little effect on the changes; the pretreated cellulose can dissolve in LiCl/DMAc system when the heating temperature is above130℃, improving the heating temperature, prolonging the heating time and increasing the concentration of LiCl can improve the solubility of the cellulose; the results of IR test show that PEG have been grafted on cellulose macromolecules successfully; by the method of this paper, the grafted solid-solid phase materials with a certain heat preservation property have been prepared, the highest phase transition enthalpy ΔHm and ΔHc of the grafted products are77.27J·g-1and60.66J·g-1, respectively; the results of TGA test indicate that when PEG is grafted on the cellulose, the temperature with maximum weight loss rate of the cellulose is increased by20℃, and its own temperature with maximum weight loss rate is also increased by10℃, which shows that the thermal stability of the grafted phase materials prepared the method of chemical grafting is superior to pure PEG.