a b s t r a c tThe manufacture of composite biofilms of alginate and LM-pectin crosslinked with calcium ions requires a two-step contact with Ca 2+ : initially a low-structured pre-film is formatted which is further crosslinked in a second contact with a more concentrated Ca 2+ solution containing plasticizer. This research evaluated the influence of the plasticizer (glycerol) concentration (1-15% w/v) in this finishing reticulation step on final films characteristics. The results indicated that the extent of the simultaneous Ca 2+ crosslinking and plasticization with glycerol was determined by the level of structural organization obtained in the pre-reticulation. Increasing the glycerol concentration of the crosslinking solution increased film solubility in water, moisture content, volumetric swelling and flexibility and decreased the resistance to tensile stress. Transparent alginate and pectin composite films with acceptable mechanical properties, low solubility and limited degree of swelling were obtained with 10% glycerol in the second contact solution.

No abstract

No abstract

Biopolymeric chitosan is considered a promising encapsulating agent for textile applications due to its biocompatibility, lack of toxicity, antibacterial activity, high availability, and low cost. After cellulose, it is nature's most important organic compound. Also, chitosan has unique chemical properties due to its cationic charge in solution. Microencapsulation technologies play an important role in protecting the trapped material and in the durability of the effect, controlling the release rate. The application of chitosan microcapsules in textiles follows the current interest of industries in functionalization technologies that give different properties to products, such as aroma finish, insect repellency, antimicrobial activity, and thermal comfort. In this sense, methods of coacervation, ionic gelation, and LBL are presented for the production of chitosan-based microcapsules and methods of textile finishing that incorporate them are presented, bath exhaustion, filling, dry drying cure, spraying, immersion, and grafting chemical. Finally, current trends in the textile market are identified and guidance on future developments.

The preparation of alginate films with suitable properties requires a two-step contact with reticulating agents: initially a weakly structured pre-film is formatted which is further crosslinked in a second stage by immersion in a more concentrated solution. The present work evaluated the effects of a combined crosslinking procedure using calcium and barium ions on the physical and morphological properties of alginate-based films containing natamycin as antimicrobial agent. The release behavior of natamycin in water was evaluated as well as the antimicrobial activity against four target microorganisms, which are common cheese product contaminants. Films attributes were affected by the type of ion used in the second stage while the natamycin release rate and the antimicrobial activity were influenced by the ion used in the first stage. Films crosslinked with Ba 2þ in the first and Ca 2þ in the second stage (BaeCa films) exhibited physical properties very similar to films crosslinked with calcium in both stages. Release kinetics of natamycin in water fitted well to Fick's second law diffusional model, with effective diffusivity values ranging from 0.40 Â 10 À11 to 1.74 Â 10 À11 cm 2 /s. BaeCa films presented the lowest natamycin diffusion coefficient and the smallest inhibition zone diameter against the four microorganisms tested.

No abstract

a b s t r a c tNatamycin, an antimicrobial agent sparingly soluble in water, was incorporated into alginate films in order to produce antimicrobial packaging, using three different approaches: the conventional loading method, when natamycin is added directly to the polymeric aqueous film-forming solution; the immersion procedure, by which a previously prepared films is contacted with natamycin solution, and by the supercritical solvent impregnation (SSI) method, with loading tests performed in CO 2 containing natamycin, with and without addition of cosolvent (ethanol, 10% molar). The loading capacities were evaluated, as well as the influence on physical attributes of the films and on the release behavior of natamycin in water. The conventional method led to films heterogeneities with high surface roughness, and the immersion technique evinced several disadvantages like low incorporation yields, and negative influence on water vapor permeability and on the swelling degree of the film. The supercritical method showed that longer contact times and the use of ethanol as a cosolvent increased the natamycin loading yields and led to homogeneous films, where SSI (CO 2 + EtOH) process produced visually attractive and tranlucent films.

In this study, we investigated different proportions of alginate and carboxymethyl cellulose (CMC) biopolymers in the formulation of films to act as wound dressings. With the casting method, monolayer and bilayer (BL) films were produced with alginate/ CMC proportions (weight percentages) of 0:100 (0A), 25:75 (25A), 50:50 (50A), 75:25 (75A), and 100:0 (100A). Thin, homogeneous, and continuous films were obtained with glycerol and crosslinking with CaCl 2 . The fluid uptake, film stability, and morphological, mechanical, thermal, and barrier properties were evaluated. A general tendency of the film characteristics was visualized: 50A had intermediary characteristics from both polymers; although the liquid behavior characteristics were improved with increasing CMC content, the mechanical properties worsened. When compared to the monolayer film (50A), the BL film 50A-BL demonstrated a better water vapor transmission rate. In this study, we demonstrated the necessity of varying the polymer concentrations to assist in the production of wound dressings.