11. Composite films of regenerate cellulose with chitosan and polyvinyl alcohol: Evaluation of water adsorption, mechanical and optical propertiesGonzalo Velazquez, Manuel Vazquez, Patricia Cazón, 2018, izvirni znanstveni članek Opis: The aimof this study was to develop composite films from cellulose, chitosan and polyvinyl alcohol to obtain environmentally friendly materials. Toughness, burst strength, distance to burst and water adsorption properties weremeasured and analysed as a function ofcellulose (3–5%), chitosan (0–1%) andpolyvinyl alcohol (0–4%) con- tents. Polynomial modelswere obtained. Light-barrier properties, transparency, morphology, structural and ther- mal analyses were assessed. Results showed that chitosan and polyvinyl alcohol enhanced the mechanical properties of cellulose-based films. Toughness values ranged from 0.47 to 8.01 MJ/m3, burst strength values ranged from 929 to 6291 g, distance to burst ranged from 1.25 to 2.52 mm and water adsorption values ranged from52.30 to 143.56%. Cellulose and chitosan improved the UV light protection effect ofthe films. However, PVA increased the transmittance meanwhile improved the film transparency. FT-IR and DSC showed an interaction between the components ofthe films. Results showed that it is feasible to obtain cellulose-chitosan-polyvinyl alcohol composite films with improvedmechanical properties, high capacity to adsorbwater, good barrier properties against UV radiations and adequate transparency value. These properties could be useful for potential packaging applications in the food industry or as a partial alternative to synthetic films
Najdeno v: osebi
Ključne besede: Regenerated cellulose, Puncture test, Water adsorption
Objavljeno: 14.12.2020; Ogledov: 1417; Prenosov: 0
 Polno besedilo (1,52 MB) |
12. Novel composite films based on cellulose reinforced with chitosan and polyvinyl alcohol: Effect on mechanical properties and water vapour permeabilityGonzalo Velazquez, Manuel Vazquez, Patricia Cazón, 2018, izvirni znanstveni članek Opis: Novel composite films were prepared by dissolving microcrystalline cellulose (3–5% w/w) in NaOH/urea solution, followed by coagulation in acetic acid solution. The regenerated cellulose films were immersed in chitosan-polyvinyl alcohol solutions at concentrations of 0–1% w/w and 0–4% w/w, respectively. Tensile strength, percentage of elongation at break, Young's modulus and water vapour permeability were measured to assess the effect of each compound on the mechanical and barrier properties. Polynomial models were obtained to evaluate the effect of the formulation on the measured properties. The microstructure was analysed by scanning electron microscopy. Results showed tensile strength values in the range 27.75–78.48 MPa, similar to usual synthetic polymer films. Percentage of elongation at break ranged from 0.98 to 12.82%, increasing when polyvinyl alcohol and chitosan increased. Young's modulus ranged from 2727.04 to 4217.25 MPa, showing higher values than pure chitosan and polyvinyl alcohol films. The highest value was reached combining cellulose and polyvinyl alcohol without chitosan. The water vapour permeability (1.78·10−11-4.24·10−11 g/m s Pa) showed 2 orders of magnitude higher than that of synthetic polymers, but lower than pure chitosan and polyvinyl alcohol films. Results showed that it is feasible to obtain cellulose-chitosan-polyvinyl alcohol composite films with improved mechanical properties and water vapour permeability.
Najdeno v: osebi
Ključne besede: Regenerated cellulose, Tensile strength, Elongation at break, Young's modulus, Water vapour permeability
Objavljeno: 14.12.2020; Ogledov: 1596; Prenosov: 0
Polno besedilo (890,78 KB) |
13. Polysaccharide-based films and coatings for food packaging: A review.Manuel Vazquez, Jose A. Ramirez, Gonzalo Velazquez, Patricia Cazón, 2017, pregledni znanstveni članek Opis: 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.
Najdeno v: osebi
Ključne besede: Cellulose, Chitosan, Starch, Water vapour permeability, Tensile strength, Percentage of elongation at break
Objavljeno: 14.12.2020; Ogledov: 1601; Prenosov: 0
Polno besedilo (722,75 KB) |
