| Abstrakt: |
Introduction. Pectin is advisable to be used for biodegradable film production. There are a lot of types of modified pectin, but its modification potential has not yet been exhausted. Materials and methods. Pectin, polyvinyl alcohol (PVA, E 1203), glycerol (E 422), oleic acid were used in this study. The vapor permeability of the film was determined according to BS EN 12086:1997. The physical and mechanical properties (strength and elongation) of the films were determined on the TIRAtest-2151 universal testing machine. Infrared (IR) spectroscopy was performed on a Nexus-475 Nicolet device. Results and discussion. The effectiveness of the pectin modification was confirmed by IR spectroscopy and elemental analysis. Efficiency was confirmed by the modification of pectin, namely, the change in molecular weight and by the appearance of new bonds and/or functional groups. The formation of pectin amide can be judged by the ν(C-N) band at 1333 cm-1. Unlike the reaction with ammonia product, the formation of salt groups with urea was not clearly visible. The disappearance of the NH2-group deformation scissor oscillation band at 1592 cm-1, as well as the shift of the C=O and C-N valence urea vibration bands may indicate the covalent bond formation between urea and pectin. The elemental analysis data indicate that the pectin esterification with ammonia, as well as with urea, took place. The film strength increased from 20.0 to 32.4 MPa and the vapor permeability decreased from 6.1 mg/(m∙h∙kPa) to 4.3 mg/(m∙h∙kPa) when content of pectin modified with ammonia in the film increased from 0.5 to 4.5%. The film elongation increased with an increase of the modified pectin content in the film. Pectin modified with urea showed a similar effect on the film properties as pectin modified with ammonia. However, the film containing pectin modified with urea was stronger, which could be explained by the formation of hydrogen bonds between the free urea amino group and OH groups in the polygalactouronic acid. The developed program based on Microsoft Office Access allows determining the biodegradable material composition based on the vapor permeability. Conclusions. Fourier-transform infrared spectroscopy (FTIR) and elemental analysis confirmed modification of pectin with ammonia or urea. The resulting material could be used to obtain ecofriendly packaging material having better physico-mechanical and barrier properties than original one. [ABSTRACT FROM AUTHOR] |
