Effect of carboxymethyl cellulose concentration on mechanical and water vapor barrier properties of corn starch films.

The main objective of this study was to evaluate the effect of the addition of different concentrations of CMC (0, 20, 40, 60, 80 and 100 %) on the mechanical and water vapor barrier properties in corn starch films produced by casting. The addition of CMC 40 % was sufficient to significantly increase its mechanical properties (tensile strength, elongation at break and elastic modulus), and water vapor barrier of the starch films, thus improving its functionality as a packaging material for food. CMC incorporation led to a small reduction in the thermal stability of the films. CMC in low content dispersed well in the starch matrix, ensuring interaction between its constituents that formed a network structure, thus improving mechanical properties and making diffusion of water difficult.

Bio-based thin films of cellulose nanofibrils and magnetite for potential application in green electronics.

The objective of this work was to prepare bio-based thin films and evaluate the additions of magnetite and glycerol on the physico-chemical (flexibility, wettability and barrier properties) and dielectric properties of cellulose/chitosan-based films. The films were prepared by solution casting and presented a suitable dispersion of the constituents observed by SEM and FTIR. The films were thermally stable up to 150 °C and had a higher flexibility, wettability and lower barrier properties upon addition of glycerol. The calculated dielectric constant (εr) for the composite films was based on measurements of capacitance, at 100 and 1000 Hz, with the additions of magnetite and glycerol more than doubling the εr increasing the charge storage capacity. The bio-based thin films have potential to be used as insulators in capacitors on the production of green electronics thus, reducing toxic and nonrenewable e-waste generation.

Solution blow spun nanocomposites of poly(lactic acid)/cellulose nanocrystals from Eucalyptus kraft pulp.

Cellulose nanocrystals (CNCs) were extracted from Eucalyptus kraft pulp by sulfuric acid hydrolysis, and esterified with maleic anhydride (CNCMA). The incorporation of sulfate ester groups on the cellulose surface resulted in higher stability of the nanoparticles in aqueous suspensions and lower thermal stability. Then, PLA/CNC and PLA/CNCMA nanocomposites were successfully obtained by solution blow spinning (SBS) using dimethyl carbonate (DMC) as solvent. CNC and CNCMA indicated to be acting both as nucleating agents or growth inhibitors of PLA crystal and tends to favor the formation of PLA crystals of higher stability. A fraction of the nanocrystals indicate to be exposed on the surface of the PLA fibers, since the hydrophilicity of the composite films increased significantly. Such composites may have potential application as filtering membranes or adsorbents.