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Food Science and Technology

Print version ISSN 0101-2061On-line version ISSN 1678-457X

Abstract

MORAES, Izabel Cristina et al. Influence of the degree of hydrolysis of poly(vinyl alcohol) on the physical properties of films based on blends of gelatin and poly(vinyl alcohol) plasticized with glycerol. Ciênc. Tecnol. Aliment. [online]. 2008, vol.28, n.3, pp.738-745. ISSN 0101-2061.  http://dx.doi.org/10.1590/S0101-20612008000300034.

The aim of this work was to study the effect of the Degree of Hydrolysis (DH) of poly(vinyl alcohol) (PVA) on the properties of films based on blends of pigskin gelatin and PVA with two DH. The films were made with solutions with 2 g macromolecules/100 g solution, containing 23.1 g PVA.100 g-1 macromolecules and 25 g glycerol/100 g macromolecules. The mechanical and thermal properties, color, opacity, moisture and solubility of the films were studied, as well as Fourier Transform Infrared (FTIR) spectra. The solutions were analyzed by dynamic rheometry. The films containing PVA with lower DH were more hygroscopic and more soluble. However, the type of PVA did not affect color, but affected the opacity and the gloss of the films. The PVA of higher DH produced films which were more resistant to puncture and stress, and the PVA of lower DH produced films which were more deformable upon stress, although less deformable upon puncture. The DH of PVA did not affect the first scan glass transition temperature of the films, but did affect this property in the second scan. The results from the FTIR analysis were in conformity with the results of the thermal analysis. The viscoelastic properties of the solutions determined by rheometry were not affected by the DH of PVA, possibly because the solutions studied were diluted.

Keywords : protein; polymer; mechanical properties; viscoelastic properties; glass transition.

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