Design Of Paraffin As A Phase Change Material, And Study On Themphysical And Flame Retardant Properties Of The Phase Change Material

Paraffin as phase change material has become the focus, because it exhibits desirable properties, such as high heat of fusion, chemical stability, controllable phase change temperature, and low cost. However, paraffin as a low molecular weight hydrocarbon suffers from a liquid leakage when it undergoes the solid-liquid phase change, low thermal conductivity and easily being burn.Based on the current studies, and the problems of paraffin as a phase change material, some kinds of excellent phase change materials based on paraffin were prepared by designing shape-stabilized phase change material and microencapsulated phase change material, also the thermal conductivity and the flame retardant properties were studied. Halogenated or intumescent flame retardant (IFR) were incorporated with paraffin to decrease fire risk, respectively; the effects between expanded graphite (EG) and halogenated flame retardant, also the effects between EG, metals or layered single hydroxide and IFR on thermophysical and flame retatdant properties of phase change material were studied; the phase change, latent heat and synergistc effect of the phase change materials were investigated, and the flame retardant mechanisms were discussed. Main research works are as follows:1. The influences of expanded graphite (EG) on thermophysical and flame retatdant properties of high density polyethylene/paraffin/chlorinated paraffinand antimony trioxide (HDPE/Paraffin/CP/AT) were studied.The differential scanning calorimetry (DSC) results indicated that the latent heat value of PCM could be increased when the mass fraction of HDPE or EG decreased, because latent heat value may be influenced by the molecular heat movement of paraffin; the volatilized products from the thermal degradation of paraffin/HDPE/CP/AT with EG showed the release of CO2 gas was hastened and increased, and the amount of combustible gases were decreased by the thermogravimetric analysis-fourier transform infrared spectrometry (TGA-FTIR) analysis; The MCC and CONE results presented that the synergistic effect between EG and CP/AT had been observed in phase change material, and the heat realease rate of the phase change material could be reduced.2. To improve thermal conductivity and flame retardant properties of shape-stabilized PCM based on paraffin and HDPE, a halogen free flame retardant shape-stabilized PCM containing paraffin, HDPE, EG and IFR was presented. The SEM results indicated that paraffin and EG were well dispersed in the network formed by HDPE. The thermal conductivity and the flame retardant efficiency of IFR could be improved by adding EG. The possible flame retardant mechanism for paraffin/HDPE/IFR/EG as a shape-stabilized PCM was that EG could migrate onto surface of the phase change material at the beginning of pyrolysis and combustion, and increase the intensity of intumescent char.3. The influences of metals on thermophysical and flame retatdant properties of intumescent flame retardant phase change material were studied, and the flame retardant mechanisms were discussed. The flame retardant efficiency of IFR in phase change material could be improved because of iron, magnesium, aluminum or zinc; the TGA-FTIR and CONE results showed that the volatilized products of combustible gases and ammonia were decreased, and carbon dioxide was increased for paraffin/IFR with metal than that of without metal, the heat realease rate of the phase change material could be reduced and flame retardant property could be improved; the thermal conductivity of PCM could be increased due to the high thermal conductivity of metal, and the influences of metal on phse change temperature and latent heat of intumescent flame retardant phase change material were unconspicuous.4. Layered zinc hydroxide nitrate (LZHN) was prepared by sol-gel method, and modified by dodecyl sodium sulfate, the organic LZHN (ds-LZHN) could be got, the basal spacing of LZHN increases from 9.91 A to 31.12 A. The micro(nano)composite which contains paraffin and ds-LZHNcould be prepared, the effects of ds-LZHN on the thermal properties for paraffin and paraffin/IFR systems were studied. the TGA, TGA-FTIR and CONE results showed that the thermal stabilities of the paraffin and paraffin/IFR systems could be improved when the ds-LZHN was incorporated, the release of the combustible gases was observably reduced, and the flame retardant efficiency of the IFR could be improved.5. The microencapsulated phase change material (Micro-PCM) based on paraffin as core and melamine-formaldehyde (MF) as shell was synthesized by in situ polymerization method, and the Micro-PCM was used into the UV coating and polyurethane foams (PUF). First, the epoxy acrylate (EA) coatings containing Micro-PCM were prepared by UV-cured, and the Micro-PCM was well dispersed in the coating; the influces of dimethyl methyl phosphonate (DMMP) and octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) on the burnning properties of EA/Micro-PCM composite were studied, and the results showed that synergistic effect could be occurred between DMMP and OVPOSS in EA/Micro-PCM composite. Secondly, Micro-PCM used as the phase change material for thermal energy storage was introduced into the PUF to improve its energy storage and temperature control roles, expandable graphite (EDG) and ammonium polyphosphate (APP) were added in the PUF to improve the thermal stability. The results showed that the conversion of energy could be effectively controlld because of Micro-PCM, and the thermal stabilities of PUF could be improved when APP and EDG incorporated into PUF.