Preparation And Properties Of Rigid Polyurethane Foam With Double Phase Transformation

Under the situation of an increasingly prominent energy problem,energy conservation and consumption reduction have become the theme of the building materials.It is of great significance to prepare the composite material with excellent temperature adjust and temperature control ability by using the phase change material(PCM)with heat storage function to modify the rigid polyurethane foam.Phase change materials usually need to be cross-linked or microencapsulated to solve the leakage,fatigue problems of phase change materials,and their interface incompatibility with surrounding materials,to improve the service life of composites.To solve the problems of the low utilization rate of phase change materials,and the high thermal conductivity in composite materials,which reduce the thermal insulation performance of rigid polyurethane foam,the solid-solid phase change polyurethane materials and silica-coated octadecane microcapsule phase change materials were prepared respectively in this paper,which was used for the composite filling modification of rigid polyurethane foam,and prepare a rigid polyurethane foam composite material with both heat preservation and temperature control ability.The main contents are as follows:1.Solid-solid phase change polyurethane(PUPCM)was prepared a two-step solvent method.Poly(ethylene glycol-4000)(PEG-4000)was bond to 4'4-diphenylmethane diisocyanate(MDI)to obtain PUPCM,and the effects of organic montmorillonite(OMMT)on the phase transition properties and crystallinity of the PUPCM system were studied.The results show that solid-solid phase change polyurethane can be successfully prepared when the molar ratio of-OH to-NCO is 1 and the molar ratio of PEG to MDI is 0.75,and OMMT can be used as a heterogeneous nucleating agent to improve the crystallization ability of the system.When the addition amount of OMMT is 0.5wt%,the melting enthalpy and crystallization enthalpy of PUPCM are 106.8J/g and 106.5J/g,respectively,and the relative crystallinity of the system enhanced from 67.0%to 75.4%.2.Silica-coated octadecane microencapsulated phase change materials(MEPCMs)were prepared by the chemical precipitation method.The effects of emulsifier type,complex emulsifier ratio,and complex emulsifier content on enthalpy value and morphology of the microcapsules were studied.The results show that the microcapsule particles prepared by the mixture of non-ionic emulsifier OP-10 and cationic emulsifier CTAB with 1:1.5 and12.5wt%of the composite emulsifier have uniform particle size and the highest latent heat value.The melting enthalpy and crystallization enthalpy are 115.2J/g and 114.5J/g,respectively,and the encapsulation efficiency is 52.03%.3.The rigid polyurethane foam(RPUF)with double phase change was prepared by filling modification.The RPUF composites were prepared by adding PUPCM with OMMT addition of 0.5wt%to the rigid polyurethane foam matrix.The results show that the more the PUPCM content,the lower the compressive strength of RPUF composites and the lower the heating/cooling rate of composites,namely the stronger the thermal insulation effect of composites.The comprehensive performance of the composite material is the best when the amount of PUPCM added is 10wt%,so MEPCMs are added on this basis to modify the RPUF composite material.The results show that the composite has a constant temperature platform at about 23~oC(the phase transition temperature of octadecane),which means that the composite can adjust and control the temperature at this temperature.