Study on the nonisothermal crystallization process of mLLDPE/EVA blends using FTIR micro-spectroscopy

摘要

The nonisothermal crystallization process has been investigated by Fourier transform infrared (FTIR) micro-spectroscopy for the 40/60 wt % blends of metallocene linear low density polyethylene (m-LLDPE) and ethylene/vinyl acetate copolymer (EVA) at the molecular level. In the cooling process, thermal spectra of mLLDPE/EVA blends were collected between 150degreesC and 67degreesC at 1degreesC interval. According to the van't Hoff equation at constant pressure, the changes of absorbance ratio corresponding to high and low vibrational states were calculated; hereby, apparent enthalpy differences of vibration energy states transformation (DeltaH(v)) of characteristic groups could be obtained. Combining with DSC analysis, two exothermal peaks were examined in the crystallization process, corresponding to mLLDPE-rich and EVA-rich domains, respectively; while in comparison of the DeltaH(v) values of various characteristic groups corresponding to the two exothermal peaks, the bending vibrational mode of methylene groups has been found to make a prominent contribution to the movement and regular arrangement of mLLDPE and EVA chain segments towards each rich domain in the crystallizing process. (C) 2005 Wiley Periodicals, Inc.