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This study reports the development and characterization of novel biodegradable film, based on chitosan and polyvinyl alcohol containing lipase entrapped. The films showed a thickness of 70.4 and 79 μm to PVA/Chitosan and PVA/Chitosan/Lipase, respectively. The entrapment of lipase in PVA/Chitosan film resulted in increasing of 69.4% tensile strength (TS), and 52.4% of elongation. SEM images showed the formation of a continuous film, without pores or cracks. The lipase entrapment efficiency was estimated in 92% and the films were repeatedly used for 25 hydrolytic cycles, maintaining 62% of initial activity. The PVA/Chitosan/Lipase film was used for olive oil hydrolysis of high performance. These results indicate that PVA/Chitosan/Lipase is a promising material for biotechnology applications such as triacylglycerol hydrolysis and biodiesel production., (Copyright © 2012 Elsevier B.V. All rights reserved.)

In this study, chitinolytic enzymes produced by Trichoderma asperellum were immobilized on a biodegradable film manufactured with a blend of cashew gum polysaccharide (CGP) and polyvinyl alcohol (PVA), and tested as a fungal growth inhibitor. The film was produced by casting a blend of CGP and PVA solution on glass molds. The CGP/PVA film showed 68% water solubility, tensile strength of 23.7 MPa, 187.2% elongation and 52% of mass loss after 90 days in soil. The presence of T-CWD enzymes immobilized by adsorption or covalent attachment resulted in effective inhibition of fungal growth. Sclerotinia sclerotiorum was the most sensitive organism, followed by Aspergillus niger and Penicillium sp. SEM micrograph showed that the presence of immobilized T-CWD enzymes on CGP/PVA film produced morphological modifications on vegetative and germinative structures of the microorganisms, particularly hyphae disruption and changes of spores shape., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Soybean hull is an agro‐industrial residue produced abundantly both in Brazil and worldwide. It is generated during the dehulling of the grains for oil production. This work aimed to develop materials using low‐cost, abundant, and biodegradable raw materials, as soybean hull, corn starch, polyvinyl alcohol (PVA), and glycerol. Five formulations of thermoplastic starch (TPS) were produced containing between 4% and 19% of ground soybean hull and another five formulations of the same composition but with 6% PVA added. The materials were extruded and injected to produce specimens. They were analyzed by FTIR‐ATR, mechanical tests, mass loss in water, and dimensional variations. The addition of hull to the TPS did not affect the processability of the materials, and the PVA improved the processability. Hull concentration from 8% to 15% increased the tensile strength of the materials, and the PVA reduced them. Soybean hull provided greater dimensional stability to the specimens, especially with PVA and with the highest hull contents (15% and 19%).Content of soy hulls between 8% and 15% acted as a structural reinforcer of TPS materials, forming a composite, as it increased the tensile strength, reduced the elongation, increased the stiffness, and improved the dimensional stability of the materials. [ABSTRACT FROM AUTHOR]

This work aimed to study the effect of modified cassava starches, and PVA grade on the properties of biodegradables sheets produce with starch/PVA blends by an extrusion-calendering process; using native starch, distarch phosphate, acetylated distarch phosphate, acetylated distarch adipate or oxidized starch; PVA with 88% and 98% hydrolysis degrees (HD), and glycerol as a plasticizer. The sheets had tensile strength, Young's modulus, and elongation that ranged from 1.0 to 6.8 MPa; 3.2 to 16.2 MPa and 130 to 443%, respectively. Sheets produced with higher HD PVA had better mechanical properties, independent of starch type. Materials produced with all starch types presented similar response for the same PVA, except those with oxidized starch, that had the poorer mechanical properties. All the sheets were visually homogeneous and had good processability. Sheets produced with higher HD PVA (98%) had better mechanical properties and higher crystallinity than those produced with lower HD PVA (88%) because the higher the HD, the higher the number of hydroxyl groups, which leads to a better interaction with the starch. The biodegradable sheets can be produced on an industrial scale because they have adequate mechanical properties and use well-known industrial techniques. [ABSTRACT FROM AUTHOR]

The aims of this work were to produce trays based on cassava starch, coated with polyvinyl alcohol (PVA) with a higher degree of hydrolysis (98%), and to study the effects of the coating on the mechanical and water sorption properties of the trays. Two types of PVA were tested: SELVOL™ 325 (degree of polymerization = 1000-1500) and SELVOL™ 107 (degree of polymerization = 350-650). A decrease in the water absorption capacity of 50% was observed when the coated samples were compared with the control sample after 30 min of immersion in water. It was observed in both coated samples a reduction of the initial rate of water adsorption sorption and a decrease in hydrophilicity compared with the control sample. Tensile strength and elongation were increased with application of the coatings. The use of the two types of PVA resulted in materials with similar mechanical and water sorption properties. [ABSTRACT FROM AUTHOR]

ABSTRACT 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. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42697. [ABSTRACT FROM AUTHOR]

Mixtures of starch and other polymers have been used to produce biodegradable materials with low-cost and enhanced properties. In this study, films containing starch mixed with alginate (ALG) and/or polyvinyl alcohol (PVOH) were characterized. Films produced using binary starch-alginate mixtures (F3, F5, and F9) had the highest tensile strength (19-28 MPa) and elongation capacity (22-17%). However, films produced using ternary starch-alginate-PVOH mixtures (F8 and F9) exhibited the best water-barrier efficacy, with lower water-vapor permeability (WVP) values (5 × 10 and 5.56 × 10−13 g/s/Pa/m1, respectively) than that of the starch films (23.60 × 10−13 g/s/Pa) and diffusion coefficient ( Dw) values approximately seven times lower than that of films produced solely with starch. The results of the infrared analyses showed a decrease in the band representing OH stretching in films created using ternary starch-alginate-PVOH mixtures, suggesting interaction between the polymers. The films containing starch mixed with ALG and PVOH showed low monolayer. The results indicated that ternary blends created better physical barriers to the passage of water vapor and diminished the availability of active sites for water binding. The optimal proportions were found to be 80% starch, 11.4% ALG and 8.6% PVOH. [ABSTRACT FROM AUTHOR]

Soybean hull is an agro-industrial residue of extensive generation in the soybean oil-producing industry, where approximately 5% of the processed volume of soy beans is converted into hulls. The main use for soy hulls is animal feed, being of great importance to find more ways of consumption for the hulls. This research proposed a noble application for soy hulls: using the hulls as a source for extracting cellulose fibers. Cellulose fibers were extracted from the hulls by alkaline treatment, ground (< 600 µm) and added to thermoplastic starch (TPS). Polyvinyl alcohol (PVA) was also added to the materials produced in order to promote better compatibility between the components. Ten formulations were produced, containing between 4 and 19 wt% of cellulose, and 2 controls. Half of the formulations contained 6 wt% PVA. Cellulose fibers and soybean hulls were characterized by FTIR-ATR and SEM, and the analyzes showed partial purification of the cellulose fibers, with a purity of 92 wt%. The composites were produced by extrusion followed by injection, and characterized by stress-strain, FTIR-ATR and dimensional stability after injection (shrinkage and warpage) tests. Cellulose fibers did not increase the tensile strength (TS) of the composites, but reduced the deformation capacity by 62% (to 19% of fibers) compared to the control. Cellulose fibers together with PVA increased the TS by up to 22% (to 19% fibers and 6% PVA in the composition), making the material more mechanically resistant. For this same formulation, the deformation capacity was reduced by a maximum of 75%, and the modulus of elasticity was increased by a maximum of 230% (the composite became more resistant and rigid). Cellulose fibers reduced the shrinkage value of the specimens, reducing the shrinkage value to less than 1% for the formulations containing 19% cellulose fibers. The cellulose fibers associated with 6% PVA had a synergistic action in the shrinkage of the specimens, further reducing the shrinkage in length (0.4% length shrinkage for 15% cellulose fibers; 0.1% length shrinkage for 19% cellulose fibers). The addition of cellulose fibers and 6% PVA to TPS made the composites more rigid and mechanically reinforced, and also with greater dimensional stability after injection. • Soybean hulls are an agro-industrial residue that requires new destinations. • PVA contributes to improving the properties of TPS materials containing cellulose. • Cellulose fibers and PVA practically zeroed the shrinkage of the specimens. [ABSTRACT FROM AUTHOR]

The use of low‐cost natural fibers is an interesting alternative to both improve the mechanical properties and reduce the cost of biodegradable materials. Oat fibers are studied as reinforcer or filler in starch/PVA biodegradable materials produced by an injection molding process, using native and cationic cassava starches. The formulations contain 45 wt% of starch + fiber, 25 wt% of PVA, and 30 wt% of glycerol, and the oat fiber proportions are 0, 2.5, 5.0, 7.5, and 10.0 wt%. All materials have good processability, and the tensile strength, Young's modulus, and elongation at break range from 4.7 to 5.5 MPa, 7.1–12.4 MPa, and 180–260%, respectively. The type of starch (native or cationic) does not influence the biodegradable material properties. The oat fiber presents a good dispersion and compatibility with the polymeric matrix, acting mainly as a filler, reducing the material costs. [ABSTRACT FROM AUTHOR]

A mixture design was used to analyse the effects of polyvinyl alcohol (PVA) on glycerol-plasticised cassava starch sheets obtained by flat extrusion from a twin-screw extruder. PVA was the main component that improved the properties of the sheets, and glycerol presented the opposite effect. The properties ranging: tensile strength (0.22-1.5 MPa), Young's modulus (0.45-7.29 MPa), elongation at break (59-111%), puncture resistance (10-107 N/mm), puncture elongation (5.64-10.13 mm), crystallinity index (17-21%) and water vapour permeability (3.39-7.40 × 10−5 g m−1 day−1 kPa−1) for the sheets. Scanning electron microscopy showed good compatibility between the components of the blend because the resultant materials were continuous and cohesive and did not exhibit phase separation. The sheets were not significantly different from others, based on XRD and FTIR analyses, consistent with the literature. PVA was able to improve the mechanical and barrier properties of starch-based sheets. [ABSTRACT FROM AUTHOR]