Preparation And Properties Studies Of PP/Paraffin Form-Stable Phase Change Materials With Low Leakage Rate

Phase change materials(PCMs)are a class of materials that use the latent heat(such as solid-liquid phase transition)of substances in the phase transition process to realize energy storage and utilization,which is the focus of energy science and material science research in recent years.Paraffin wax is a commonly used organic solid-liquid phase transition materials.It has been widely studied and applied because of its high latent heat,non-toxic and odorless,stable performance,rich variety,low price,and wide range of sources.Paraffin wax has the problem of leakage during the solid-liquid phase transition,so it cannot be used directly and needs to be packaged.At present,the main methods of encapsulating paraffin wax are microcapsule method,porous adsorption method and physical blending method.Physical blending is more popular and suitable for industrialization.However,there are many problems at present.The main problem is that the blending process of phase change materials and polymers is not easy to process,and the prepared form-stable phase change materials have high leakage rate and poor form stability.In view of this,this paper proposes a method of preparing paraffin-based form-stable phase change materials with polypropylene(PP)as a support material by first increasing the viscosity of paraffin and then melt blending.By investigating the influence of the type and amount of viscosifiers on the viscosifying efficiency and thermal performance of paraffin,the type and amount of viscosifiers for viscosifying paraffin were determined.After that,the PP/paraffin form-stable phase change material is prepared by blending the viscosifying paraffin wax with PP.The effect of the viscosifiers on the leakage rate,form stability.,thermal performance,crystallization performance and phase morphology of the PP/paraffin form-stable phase change material is determined.The dosage and optimal formulation of the viscosifiers for preparing PP/paraffin form-stable phase change materials with excellent form stability and low leakage rate were obtained.And on this basis,the preparation of PP/inorganic powder/paraffin form-stable phase change composite materials with excellent form stability and low leakage rate was explored.The specific research conclusions are as follows:(1)Elastomers EPDM,POE,SEBS can significantly increase the viscosity of paraffin wax.SEBS has the best viscosity-increasing effect.Adding 10wt% can increase the viscosity of paraffin wax by 268.9 times.POE and EPDM have basically the same viscosity-increasing effect on paraffin wax.(2)The use of viscosifying paraffin wax can effectively solve the problem of liquid leakage and uneven mixing during the preparation of PP/paraffin form-stable phase change materials by melt blending,and can obtain PP/paraffin form-stable phase change materials with low leakage and good form stability.(3)Elastomers SEBS and POE have a synergistic effect.The use of SEBS and POE to increase the viscosity of paraffin can be used to prepare PP/paraffin form-stable phase change materials with excellent form stability and low leakage rate.When the optimal weight ratio of SEBS and POE is 5/15,and their addition amount is 20wt% of the weight fraction of paraffin,the leakage of the prepared PP/paraffin form-stable phase change material at a constant temperature of 80°C for 48 hours is only 1.41%,and no deformation will occur at a constant temperature of 100°C for 30 minutes.(4)Talc is more suitable than diatomite for the preparation of paraffin-based form-stable phase change composite materials with PP as the support material.The addition of talc can promote the mixing of PP and paraffin,and enhance the coating of paraffin by the support material.When the addition amount is 10wt%,the PP/talc/paraffin form-stable phase change composite material has the lowest leakage rate and the best high-temperature form stability.