Preparation and characterization of the ethylene‐vinyl acetate copolymer partially hydrolyzed assisted by microwave radiation

Ethylene-vinyl acetate copolymer (EVA) was modified by hydrolysis using dielectric heating. The modified EVA was characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis (TG), 1H Nuclear magnetic resonance (NMR), gel permeation chromatography, and small-angle X-ray scattering. The results showed that the EVA was hydrolyzed with degree between 36.1 and 42.6% according to 1H NMR and TG results. The relative reaction rate for the sample prepared in the oil bath was ∼9%/h, while in the dielectric was ∼150%/h for 15 min. This significant improvement was due to the specific effect of microwave-assisted reactions through dipole rotation and ionic polarization contributions. The hydrolysis reaction promoted a reduction of the pendent group size of EVA backbone. This change directly contributed to increasing melt temperature, crystallization temperature, melt and crystallization enthalpies. Also, decreased the long period, increased the volume crystallinity, and caused reductions amorphous/crystalline interface and two-phase model deviations. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44558.