Properties And Testing Methods Of Phase Change Fibers

When polyethylene glycols(PEG) has a reversible heating and cooling, its super molecule structue will have some change in macroscale of its properties called phase transition. The PEG has a special accumulation of heat and regulation to temperature. These properties are showed when it exotherms at high temperature and endotherms at low temperature. Because the temperatures in phase change of PEG are in the range of natural environmental condition, moreover, it is found that PEG can physically or chemically conjoint with fibers, so it has the possibility to add to fabrics and some other textile materials, and endure the fabrics the function of regulating temperature.Because it has long molecule, different molecular weight, and imperfect crystal structure, the temperature of melting is ranged, unlike the low molecular weight material, has a prominence peak. Because of the melt property, the process of phase change is stable and controllable, the phase detaches will not happen easily. Besides these, the material can be shaped well, the erosion is small, the behavior is steady, toxicity is small and costs less. Though we can select different molecular weight theoretically to achieve the factual demands, it is difficult to make. But we can mix the PEG with different molecular weights, then we can solve these problems and achieve better properties than monocomponent PEG. Especially when equitably mix different molecular PEG, we can get the material that it's suitable to adaptable phase change fiber for wear. By testing the two PEG systems with DSC, the better mixture will be abtained.The experiments of DSC on different content PEG have been done in order to get suitable PEG system. The results show that the two system isn't simply added by the monocomponent. But it appears twodifferent peak. It can be said that, the two different component generate something physical change because the different states during the process. It is probable that the PEG molecular weight resort and reorientation, and correspondingly the characteristic parameters change.The system is changed into solution by adding water and hollow fibers are filled with the solution in vacuum. Moreover, the affection of solution concentration, solution temperature and fibers length on the filling have been analyzed. The results show that: (1) at normal temperature, filling ratio rises to the maximum at 50% of solution concentration; (2) the length of hollow fibers influences the filling ratio slightly; (3) the filling ratios becomes large with the increase of temperature. But the solution at large concentration has more notable effects on the filling ratio than one of small solution at the same temperature.DSC experiments have been done on the filled fibers. The results show that the Tm and Hm of filled fibers are nearby similar to PCMs. After 8 heating cycles, the Tm and A Hm reduce a little, so that the fibers can be used repeatedly. The tensile measurements show that the strength and abrasion of the filled single fiber have changed respectively. To characterize the other properties of the phase change fibers, we establish a heat transfer model and the model can get fibers' conductive coeffient , density and other parameters. The IR graph proves that PCMs have been filled into fibers.