Preparation And Characterization Of Cellulose Ether Solid-solid Phase Change Membrane

With the increasing concern on the shortage of petroleum resources, energy crisis and environment pollution, the eco-friendly Phase Change Materials draw widely attention. Polyethylene glycol(PEG),as the most commonly used phase change material, has the advantages of simple molecular structure, easy crystallization, high heat of phase transition and low heat-hysteresis influence. But PEG is solid-liquid phase change material which limits its application in phase change materials. PEG can be changed into solid-solid phase change material through modification. Using cellulose ethers which are abundant, low-cost, biodegradable and biocompatible as the base material, through hydrogen-bonding between the PEG molecular and the cellulose ether, Cellulose Ether solid-solid phase change membrane was prepared through physical blending method in this article/(research), and the different blending ratio of the films were characterized and analyzed. And by adding cellulose nanofibers(CNFs), the phase change membrane were modified and optimized.First, the PEG-CMC solid-solid phase change membrane was prepared by using ionic cellulose ether, carboxymethyl cellulose(CMC) as base material. It's found that the binding effect of the hydrogen-bonding between the CMC and the PEG was not ideal. In the phase change membrane, the highest PEG content was 30%. With the increase of the PEG content, the thermal stability of the phase change membranes was not significantly affected, the transmittance decreased, the heat of phase transition increased, the breaking strength reduced and the elongation at break increased.On this basis, PEG-HPMC solid-solid phase change membrane was prepared by using Non-ionic cellulose ether, hydroxypropyl methyl cellulose(HPMC) as base material. The research found that the binding effect of the hydrogen-bonding between the CMC and the PEG was improved. In this phase change membrane, the highest PEG content was 40%. With the increase of the amount of PEG, the thermal stability and heat of phase transition of the phase change membrane increased, the breaking strength reduced, and the elongation at break firstly rose and then declined. The transmittance was significantly affected, and the transmittance in the visible wavelength range of the phase change membrane declined to 0% when the amount of PEG content was at 20% and above.In order to improve the overall performance of the solid-solid phase change membrane, the PEG-HPMC-CNFs solid-solid phase change membrane was prepared by using the CNFs as modification filler. It's found that the addition of the CNFs had little effect on the thermal stability and heat of phase transition of the phase change membrane, but it effectively improved the transmittance of the phase change membrane. When the CNFs were added to 2%~4%, the transmittance in the visible wavelength range of the phase change membrane was 80%, while the breaking strength and elongation at break increased significantly when the CNFs content was at 3%.