Preparation And Characterization Of Phase Change Material Used In Fruit Packaging

Low temperature preservation of fruit is very irmportant in the process of fruit storage and transportation, and it has an important impact on the taste and the value of fruit. As a result, the preparation of a kind of phase change materials which is used in the storage and transportation of fruit is of great signification. This paper is to choose a kind of suitable phase change material for the fruit's low temperature storage and transportation according to the requirements of the phase change materials selection, and to improve the properties of the selected material, in order to get a kind of phase change material with more excellent performance. In this paper, the main research includes:First of all, properties of five materials are analyzed and compared, namely calcium chloride hexahydrate (CaCl2·6H2O),sodium sulfate decahydrate (Na2SO4·10H2O),caprylic acid (C8H16O2), Sodium polyacrylate hydrogel (PAAS) and polyethylene glycol (PEG). Their advantages and disadvantages are also discussed. According to the requirements of phase change materials, PAAS was chosen as the phase change material which would be used in fruit low temperature storage and transportation. Sodium polyacrylate hydrogel/ cellulose nanocrystal composite phase change material is prepared by physical mixing in order to improve PAAS's disadvantages of low strength and nonadjustable phase change temperature.Secondly, the preparation of the cellulose nanocrystal by acid hydrolysis is researched, and also the effects of experimental materials ratio, experiment time and experiment temperature.The result shows the optimal condition as follows: ratio of microcrystalline cellulose and concentrated sulfuric acid of 1g:11ml, reacting temperature of 45?. reacting time of 90min.Thirdly, the study on water absorbing and phase change mechanism of Sodium PAAS shows Phase change latent heat increased with the increase of water quantity, while phase change temperature is constant.Fourthly, research the effect of different ratio of sodium polyacrylate hydrogel and cellulose nanocrystal on the properties of the composite phase change material by using DSC,including the impact of cellulose nanocrystal on the phase change temperature, phase change latent heat, hydrogel strength and water retaining property of the composite phase change material, in order to get a kind of composite phase change material with excellent performance.The effect of water quantity on the properties of composite phase change material is also analyzed.In this paper, the research on the application of phase change material in fruit which is stored and transported in low temperature is of great reference value, can also provide effective basis and guidance for the use of phase change materials in fruit.