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1.
Regenerated cellulose films with chitosan and polyvinyl alcohol: Effect of the moisture content on the barrier, mechanical and optical properties
Gonzalo Velazquez, Manuel Vazquez, Patricia Cazon, 2020, original scientific article

Abstract: The aim of this research was to evaluate the effect of moisture content on the mechanical, barrier and optical properties of films obtained from regenerated cellulose with chitosan and polyvinyl alcohol equilibrated at several relative humidity conditions. The experimental moisture adsorption isotherms were fitted using the Guggenheim-Anderson-DeBoer model. The adsorption isotherm showed a typical type II sigmoidal shape. The highest moisture content (27.53 %) was obtained at a water activity of 0.9. The water vapour permeability values increased up to 6.34·10−11 g/ m s Pa as the moisture content of the films increased. Tensile strength, percentage of elongation, Young’s modulus, burst strength and distance to burst showed a significant plasticizing effect of the water molecules. Results suggest that interactions between film components and water molecules decrease the transmittance in the UV region and the transparency. Consequently, water molecules improve the UV-barrier properties of the films and increasing the opacity.
Found in: ključnih besedah
Keywords: Adsorption isotherms, Plasticization, Regenerated cellulose, Chitosan, Polyvinyl alcohol, Water vapour permeability, Moisture content
Published: 09.12.2020; Views: 825; Downloads: 0
.pdf Fulltext (588,35 KB)

2.
Mechanical and barrier properties of chitosan combined with other components as food packaging film
Patricia Cazon, Manuel Vazquez, 2019, review article

Abstract: Chitosan is an alternative to synthetic polymers for food packaging. The mechanical and barrier properties of pure chitosan films are promising. Chitosan properties can be modified by combining chitosan with other components such as plasticizers, other polysaccharides, proteins and lipids. Here we review mechanical and barrier properties of composite films based on chitosan. The major points are: (1) compared with synthetic plastic films, an important limitation of chitosan-based films is their mechanical properties, especially their capacity to elongation; (2) chitosan is a polymer that allows an easy combination with other polysaccharides, plasticizers, proteins and lipids; (3) this allows to develop mixed components and modify the film properties according to the nature of the food to be packaged.
Found in: ključnih besedah
Keywords: Chitosan, Film, Mechanical properties, Barrier properties, Food packaging
Published: 09.12.2020; Views: 781; Downloads: 0
.pdf Fulltext (846,53 KB)

3.
Designing new renewable nano-structured electrode and membrane materials for direct alkaline ethanol fuel cell
Egon Pavlica, Ahmed Kreta, Gvido Bratina, final research report

Found in: ključnih besedah
Summary of found: ...graphene, membrane, chitosan, polysaccharide, fuel cell, alkaline, ethanol, morphology, elemental...
Keywords: graphene, membrane, chitosan, polysaccharide, fuel cell, alkaline, ethanol, morphology, elemental analysis
Published: 03.12.2020; Views: 834; Downloads: 0
.pdf Fulltext (19,13 MB)

4.
Designing new renewable nano-structured electrode and membrane materials for direct alkaline ethanol fuel cell
Egon Pavlica, Ahmed Kreta, Gvido Bratina, final research report

Found in: ključnih besedah
Summary of found: ...graphene, chitosan, polysaccharide, fuel cell, alkaline, ethanol, photoconductivity, ionic...
Keywords: graphene, chitosan, polysaccharide, fuel cell, alkaline, ethanol, photoconductivity, ionic conductivity, mixed-conductor model
Published: 03.12.2020; Views: 807; Downloads: 0
.pdf Fulltext (10,55 MB)

5.
TOXIC CHEMICALS AND TOXINS IN THE ENVIRONMENT AND TECHNOLOGIES FOR THEIR DETECTION AND REMOVAL
Mladen Franko, invited lecture at foreign university

Found in: ključnih besedah
Keywords: Microcystin, MRI contrast agents, pesticides, biocomposites, keratin, chitosan
Published: 01.03.2017; Views: 2629; Downloads: 0
.pdf Fulltext (40,68 MB)
This document has many files! More...

6.
Characterization of bacterial cellulose films combined with chitosan and polyvinyl alcohol: Evaluation of mechanical and barrier properties
Manuel Vazquez, Gonzalo Velazquez, Patricia Cazon, 2019, original scientific article

Abstract: Bacterial cellulose (BC) produced by Komagataeibacter xylinus is a biomaterial with a unique three-dimensional structure. To improve the mechanical properties and reinforce the BC films, they were immersed in polyvinyl alcohol (0–4%) and chitosan (0–1%) baths. Moisture content, mechanical properties and water vapour perme- ability were measured to assess the effect of polyvinyl alcohol and chitosan. The morphology, optical, structural and thermal properties were evaluated by scanning electron microscopy, spectral analysis, thermogravimetry and differential scanning calorimetry. Results showed that moisture content was significantly affected by the chitosan presence. Tensile strength values in the 20.76–41.65 MPa range were similar to those of synthetic polymer films. Percentage of elongation ranged from 2.28 to 21.82% and Young's modulus ranged from 1043.88 to 2247.82 MPa. The water vapour permeability (1.47×10−11–3.40×10−11 g/m s Pa) decreased with the addition of polyvinyl alcohol. The developed films own UV light barrier properties and optimal visual appearance.
Found in: ključnih besedah
Keywords: Films, Bacterial cellulose, Water vapor permeability, Chitosan, Polyvinyl alcohol, UV protection
Published: 14.12.2020; Views: 677; Downloads: 0
.pdf Fulltext (1,78 MB)
This document has many files! More...

7.
Polysaccharide-based films and coatings for food packaging: A review.
Manuel Vazquez, Jose A. Ramirez, Gonzalo Velazquez, Patricia Cazon, 2017, review article

Abstract: The accumulation of synthetic plastics, mainly from food packaging, is causing a serious environmental problem. It is driving research efforts to the development of biodegradable films and coatings. The biopolymers used as raw material to prepare biodegradable films should be renewable, abundant and low-cost. In some cases, they can be obtained from wastes. This review summarizes the advances in polysaccharide-based films and coatings for food packaging. Among the materials studied to develop biodegradable packaging films and coatings are polysaccharides such as cellulose, chitosan, starch, pectin and alginate. These polysaccharides are able to form films and coatings with good barrier properties against the transport of gases such as oxygen and carbon dioxide. On the other hand, tensile strength and percentage of elongation are important mechanical properties. Desirable values of them are required to maintain the integrity of the packed food. The tensile strength values showed by polysaccharide-based films vary from each other, but some of them exhibit similar values to those observed in synthetic polymers values. For example, tensile strength values of films based on high amylose starch or chitosan are comparable to those values found in high-density polyethylene films. The values of percentage of elongation are the main concern, which are far from the desirable values found for synthetic polymers. Researchers are studying combinations of polysaccharides with other materials to improve the barrier and mechanical properties in order to obtain biopolymers that could replace synthetic polymers. Functional polymers with antimicrobial properties, as that the case of chitosan, are also being studied.
Found in: ključnih besedah
Summary of found: ...and coatings are polysaccharides such as cellulose, chitosan, starch, pectin and alginate. These polysaccharides are...
Keywords: Cellulose, Chitosan, Starch, Water vapour permeability, Tensile strength, Percentage of elongation at break
Published: 14.12.2020; Views: 769; Downloads: 0
.pdf Fulltext (722,75 KB)

8.
Chitosan and their derivatives: Antibiofilm drugs against pathogenic bacteria
Fazlurrahman Khan, Dong Pham, Sandra Oloketuyi, Panchanathan Manivasagan, Junghwan Oh, Young-Mog Kim, 2020, review article

Abstract: Biofilm formed by several pathogenic bacteria results in the development of resistance against antimicrobial compounds. The polymeric materials present in the biofilm architecture hinder the entry of antimicrobial compounds through the surface of bacterial cells which are embedded as well as enclosed beneath the biofilm matrix. Recent and past studies explored the alternative approaches to inhibit the formation of biofilm by different agents isolated from plants, animals, and microbes. Among these agents, chitosan and its derivatives have got more attention due to their properties such as biodegradability, biocompatibility, non-allergenic and non-toxicity. Recent researches have focused on employing chitosan and its derivatives as effective agents to inhibit biofilm formation and attenuate virulence properties by various pathogenic bacteria. Such antibiofilm activity of chitosan and its derivatives can be further enhanced by conjugation with a wide range of bioactive compounds. The present review describes the antibiofilm properties of chitosan and its derivatives against the pathogenic bacteria. This review also summarizes the mechanisms of biofilm inhibition exhibited by these molecules. The knowledge of the antibiofilm activities of chitosan and its derivatives as well as their underlying mechanisms provides essential insights for widening their applications in the future.
Found in: ključnih besedah
Keywords: Antibiofilm, Biofilm inhibition, Chitosan, Chitosan derivatives, Pathogenic bacteria
Published: 14.01.2021; Views: 726; Downloads: 0
.pdf Fulltext (3,95 MB)

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