Abstract: Using the bridging role of tolylene diisocyanate(TDI), poly(vinyl alcohol)-g-tolylene diisocyanate-fatty alcohol copolymers were synthesized with the fatty alcohols as the thermal storage units along the PVA backbone via the "grafting to" method. The thermal storage behavior, thermal stability and crystalline structure of PVA-g-TDI-C(n) copolymers were detailed investigated by Fourier transform infrared spectroscopy(FTIR), differential scanning calorimetry(DSC), thermogravimetric analysis(TGA), X-ray diffraction(XRD). The results show that PVA-g-TDI-C(n) copolymers exhibit the better thermal storage ability, and the value of enthalpy increases with the side-chain length and the grafting ratio. Compared with the pure fatty alcohols, the grafted ones show the decreased thermal storage efficiency due to the confined mobility of longer methylene groups. Besides the confined mobility of methylene groups, the effect of PVA backbones and the bridging units of TDI also contribute to the decrement of thermal storage ability of PVA-g-TDI-C(n) copolymers. Additionally, PVA-g-TDI-C(n) copolymers exhibit the higher thermal stability than that of pure n-fatty alcohol, and the thermal degradation temperature is located at 324-330 ℃, proving that it can be used as the solid-solid phase change materials in the aspects of buildings, fiber and textiles, thermal fluids, etc. So, the packing manner and thermal behavior of PVA-g-TDI-C(n) copolymers were further discussed and analyzed from the viewpoints of microstructural mobility.

Key words: Poly(vinyl alcohol), Thermal energy storage, Comb-like polymer, Phase change material