Studies On The Preparation And Properties Of Polyether Type Phase Change Materials

Suspension polyether type form-stable phase change materials (PCMs) were synthesized in this thesis. This kind of PCM was prepared by polymerizing or chemical grafting polyether type PCMs into higher melting point polymeric materials, which acts as supporting materials. When the temperature is below the melting point of the supporting materials, the PCMs can work as the energy storage working materials component of form-stable phase change materials.Styrene maleic anhydride copolymer (SMA) was prepared by precipitation polymerization with BPO as initiator in toluene. A simple and speed potentiometric titration method was established to determine the proportion of maleic anhydride of SMA.Suspension polyether type form-stable PCMs (SMA-g-PEG) were easily synthesized by the reaction of SMA with PEG, which was due to the high reactive anhydride groups in SMA. The influence of reaction solvent and catalyst on grafting reaction was discussed in detail. The results were as following:the utilization factor of PEG reached 99.0% under the conditions of MEK/THF of reaction solvent, triethylamine (TETN) of catalyst. A novel suspension polyether type form-stable PCM (SMA-g-mPEG) was synthesized by the reaction of SMA with mPEG (mPEG2000, mPEG5000). Its structure was studied by FTIR and'HNMR.The form-stable, energy storage capability, thermal stability, and crystallinity of SMA-g-PEG and SMA-g-mPEG were studied by the apparent form, differential scanning caborimetry (DSC), thermogravimetry (TG) and X-ray diffraction (XRD). The results showed that:SMA-g-PEG and SMA-g-mPEG were form-stable at 70℃and had better shape stability than pure PEG and mPEG; the phase change enthalpy of SMA-g-PEG2000 (70%), SMA-g-PEG4000 (70%), SMA-g-PEG6000 (70%), SMA-g-PEG10000 (80%) and SMA-g-PEG20000 (80%) were 104.4J/g,101.4J/g,109.2J/g,123.8J/g and 120.1J/g, respectively; the phase change enthalpy of SMA-g-mPEG2000(70%) and SMA-g-mPEG5000 (70%) were 96.2J/g and 92.0J/g respectively; XRD results showed that the crystallinity of SMA-g-PEG and SMA-g-mPEG were lower than PEG and mPEG; TG results showed that SMA-g-PEG and SMA-g-mPEG were all stable at lower than 250℃A novel polymeric form-stable PCM (PPEGMA-DVE) was synthesized by the reaction of divinyl benzene (DVB) with poly(ethylene glycol) methyl ether methacrylate (mPEGMA) by solution polymerization with BPO as initiator. The influence of reaction time, reaction temperature, monomer concentration, ratio of DVB to mPEGMA, and initiator dosage on polymerization were discussed in detail. Its structure was analysed by FTIR. Analysis results of DSC showed that the phase change enthalpy of PPEGMA-DVE1100 and PPEGMA-DVE2080 were 45.3J/g and 100.7J/g, respectively.Poly(polyethylene glycol methyl ether methacrylate) (PPEGMA1100 and PPEGMA1100) as novel form-stable phase change materials for thermal energy storage were prepared via the facile bulk polymerization of mPEGMA1100 and mPEGMA2080. PPEGMA was characterized by FT-IR, XRD, DSC and TGA measurements. The results showed that:the phase change enthalpy of PPEGMA1100 and PPEGMA2080 were 94.2J/g and 108.6J/g respectively; XRD results showed that the crystallinity of PPEGMA and mPEGMA was similar; TG results showed that PPEGMA was very stable.