Starch and polyvinyl alcohol (PVA) are biodegradable materials with potentiality to replace the conventional polymers in some applications. The aim of this work was to produce biodegradable films of PVA, cassava starch, and glycerol by thermoplastic extrusion using a mixture design to evaluate the effects of each component in the blend properties. Six formulations were prepared using a twin-screw extruder coupled with a calender. All the materials were visually homogeneous and presented good processability. Mechanical properties were dependent on both the relative humidity conditioning and the formulation; higher relative humidities detracted the mechanical properties, which was associated to plasticizer effect of the water. Furthermore, the mechanical properties were better when higher concentrations of PVA were used, resulting in films with lower opacity, lower water vapor permeability, and higher thermal stability, according to TGA. Biodegradable materials based on starch, PVA, and glycerol have adequate mechanical and processing properties for commercial production.

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ResumoForam produzidos 12 laminados com diferentes proporções de amido de mandioca, poli(vinil álcool) (PVA) e glicerol por extrusão usando um planejamento de mistura. A opacidade dos materiais variou entre 31 e 56%, e a concentração de PVA e a interação entre as concentrações de amido e PVA foram os principais responsáveis pelo aumento da opacidade. A diferença de cor (ΔE*) variou entre 20-30, sendo a concentração de amido o principal responsável pelo aumento da diferença de cor, por promover uma coloração mais amarelada nos laminados. Palavras-chave: extrusão, biopolímeros, propriedades ópticas. CbstractTwelve sheets were produced by extrusion with different proportions of cassava starch, poly (vinyl alcohol) (PVA) and glycerol using a mixture design. The opacity of the materials ranged from 31 to 56%, and the concentration of PVA and the interaction between starch and PVA concentrations the mainly responsible for increasing opacity. The color difference (ΔE*) ranged from 20 to 30, the concentration of starch being primarily responsible for increasing in color difference by promoting a more yellowish color in sheets.

This research aimed to develop blends of corn starch and poly(butylene adipate-coterephthalate) (PBAT) films by blown film extrusion with the addition of biomass of Chlorella pyrenoidosa (CP). Two ultrasound tracts disrupted CP biomass: ultrasound bath and ultrasonic probe. The influence of CP biomass and disrupted CP biomass on the physical, mechanical, barrier, structural, and thermal properties of starch/PBAT films was evaluated. The film with higher content (5.0%) of CP biomass showed better values in tensile strength (TS) (4.37 MPa) and elongation (88.43%), and lower water vapor permeability (WVP) (5.19 Â 10 À11 g m À1 s À1 Pa À1 ) than the film incorporated with disrupted CP biomass. The ultrasound treatment applied to the cell disruption of the microalgae did not present improvements in the properties of the films. In this context, the cell disruption of CP biomass by ultrasound for incorporation into biodegradable films was not feasible. However, it was possible to produce starch/PBAT/microalgae films with potential application as food packaging due to natural bio-pigmentation's protection system against ultraviolet light. Practical ApplicationsFilms produced by blown extrusion from starch, PBAT, and CP microalgae biomass have the technological potential to be used as packaging for food products. Starch and PBAT blends are widely studied. The incorporation of PBAT is necessary to confer adequate mechanical properties to the extruded material. The plastic industries already use the blown extrusion method, allowing biodegradable packaging development on an industrial scale.