2 resultados para Filamentation and biofilms

em Repositório Institucional da Universidade Federal do Rio Grande - FURG


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Chitosan biofilms were prepared with and without plasticizer (glycerol and sorbitol). The physical and mechanical properties of chitosan biofilms with and without plasticizer were evaluated. Chitosan was obtained from shrimp wastes and characterized. The film forming solution (FFS) was obtained through chitosan dissolution and drying. The solution had its pH adjusted to 6.0 and oven dried (40 8C, 24 h) with forced air circulation. Chitosan biofilms without plasticizer showed a tensile strength about 36% higher than biofilms produced with plasticizer. On the other hand, biofilms with plasticizer presented superior values of elongation. The permeability of the water vapor and color presented significant difference (p<0.05) between all biofilms. Chitosan/plasticizer biofilms showed higher values of water vapor permeability in relation to chitosan biofilms without plasticizer.

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Chitosan is a polysaccharide derived from chitin, mainly of crustacean shells and shrimp wastes. The utilization of chitosan is related to the molar weight and deacetylation degree of the biopolymer. The aim of this work is to study the chitin deacetylation reaction, by the viscosity average molar weight and deacetylation degree of chitosan as a function of reaction time. Deacetylation was carried out in concentrated alkaline solution, 421 g L−1, at 130◦C and the reaction occurred during 4 h. Chitosan paste obtained after 20, 90 and 240 min was used to produce biofilms, which were characterized according water vapor permeability and mechanical properties (tensile strength and percentage tensile elongation at break). During the reaction time deacetylation degree reached 93%, and a 50% reduction in the viscosity average molar weight value in relation to the value of the first 20 min of reaction was found Both reactions presented a kinetic behavior of the pseudo-first order. Biofilm produced from the paste of chitosan with high deacetylation degree showed higher water vapor permeability (WVP), tensile strength (TS) and elongation (E) when compared to films with a low deacetylation.