Preparation And Characterization Of A Novel Polyurethane Solid-Solid Phase Change Materials

Polyurethane phase change materials(abbreviated as PUPCM) is an important research subject of phase change materials research. Polyurethane phase change materials (PUPCMs) have many excellent properties, for example, no liquid or gas generation, small volume change, no receptacle needed to seal them, easily being processed into expected shape, even being used as a system materials directly. Thus, it can obviously simplify fabrication procedures and cut down costs.This paper is composed of two parts. In the first part, a series of polyurethane solid-solid phase change materials were synthesized using polyethylene glycol (PEG) as soft segment and 4, 4’-diphenylmethane diisocyanate (MDI) as hard segment. The composition, structure and phase change properties were characterized and the best reaction process conditions were determined. The experimental results showed that:under the same conditions, the phase transition enthalpy of phase change materials is in proportion to the molecular weight of PEG. In the same condition, the optimum reaction conditions as follow:the reaction time is 6h, reaction temperature is 70℃, R ([NCO]/[OH]) has a value of 1.01. The PCM appeared typical solid-solid phase transition property and the phase change enthalpy and phase transition temperature reached to 168.44 J/g and 53.96℃, respectively. Finally, the mixer of PCMs and polyurethane adhesive was used to make film. The phase change properties and water resistance were analyzed. Preparation of PCM with higher the molecular weight of PEG, the greater the phase transition enthalpy. The film appeared typical solid-solid phase transition property and good water resistance.In the second part, starting from the molecular chain structure design, the polyurethane phase change materials above were improved. The molecular chain is blocked by MPEG Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermo gravimetric analyzer (TGA) and polarization optical microscopy (POM) were used to analyze the properties of materials. The experimental results showed that the phase transition enthalpy of phase change materials is in proportion to the molecular weight of PEG under the same conditions. The optimum reaction conditions as follow:the reaction time is 8h, reaction temperature is 70℃. The results indicated that the PCM appeared typical solid-solid phase transition property. The phase change enthalpy and phase transition temperature reached to 120.45 J/g and 37.32℃, respectively. Finally, the polyurethane film are prepared by blending PCM and polyurethane adhesive. The thermal characteristics and water resistance were investigated. When the PCMs was synthesized by PEG4000, The film appeared typical solid-solid phase transition property and highest phase transition enthalpy. And good water resistance. Compared with the film made in the first part, the film of part 2 has higher phase change transition enthalpy and poor water resistance.