Juliano Zanela

Laminados biodegradáveis de blendas de amido de mandioca e poli(vinil álcool): efeito da formulação sobre a cor e opacidade

Twelve 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.

Biodegradable blends of starch/polyvinyl alcohol/glycerol: multivariate analysis of the mechanical properties

The aim of the work was to study the mechanical properties of extruded starch/polyvinyl alcohol (PVA)/glycerol biodegradable blends using multivariate analysis. The blends were produced as cylindrical strands by extrusion using PVAs with different hydrolysis degrees and viscosities, at two extrusion temperature profiles (90/170/170/170/170 °C and 90/170/200/200/200 °C) and three conditioning relative humidities of the samples (33, 53, and 75%). The mechanical properties showed a great variability according to PVA type, as well as the extrusion temperature profile and the conditioning relative humidity; the tensile strength ranged from 0.42 to 5.40 MPa, elongation at break ranged from 10 to 404% and Young’s modulus ranged from 0.93 to 13.81 MPa. The multivariate analysis was a useful methodology to study the mechanical properties behavior of starch/PVA/glycerol blends, and it can be used as an exploratory technique to select of the more suitable PVA type and extrusion temperature to produce biodegradable materials.

Armazenamento de sementes de cerejas-do-mato (Eugenia involucrata) DC. submetidas ao recobrimento com biofilmes e embalagem a vácuo

Fruit trees such as Eugenia involucrata are still unexploited, therefore technical information that encourages farmers to use them is needed. The seed propagation method is usualy used since there is the risk of losing its viability with storage. The objective of this work was to evaluate the hydropriming and storage techniques (vacuum and biofilm), during storage at five and 30 days of E. involucrata seeds. The study was carried out at Universidade Tecnologica Federal do Parana - Dois Vizinhos campus, Parana State, Brazil. The experimental design was a randomized block, in the 2 × 4 × 2 factorial design (hydropriming x storage technique x storage time), with 4 replications of 50 seeds per plot. The extracted seeds were separated into two groups: one was submitted to pre- hydropriming in distilled water for 24 hours and the other not. Hydroprimed or not-hydroprimed seeds were submitted to four storage techniques: vacuum plastic packaging, cassava starch biofilm seed coated (3% w/v), vacuum plastic packaging + cassava starch biofilm and no treatment (control). Afterwards, the seeds were kept in a cold chamber at 5oC and 85% relative humidity for five and 30 days. One hundred and ten days after sowing, the germination percentage, emergence speed index and total dry matter mass of the plantlets were evaluated. For storage of E. involucrata seeds, the vacuum technique with or without biofilm coating should be used.

Polyvinyl alcohol (PVA) molecular weight and extrusion temperature in starch/PVA biodegradable sheets

The aim of this work was to study the relationship of chain size of partially hydrolyzed PVA blended with starch in properties of biodegradable sheets produced by thermoplastic extrusion. It was also studied the effect of extrusion temperature profile to determine the better PVA chain size and temperature profile to produce biodegradable sheets through a factorial design. The processability and the mechanical, thermal, optical, and microstructural properties of the biodegradable sheets were adequate, indicating that PVA/cassava starch blends have potential to replace conventional non-biodegradable polymers. Tensile strength and Young’s modulus ranges from 1.0 to 2.6 and 3.0 to 6.9 MPa respectively, the elongation at break ranges from 42 to 421%. It was not possible to state a conclusive relationship between PVA molecular weight and the materials properties, but in general, PVA with medium molecular weight and high extrusion temperature profile promote an increase of mechanical properties of the sheets.

Influence of microcrystalline cellulose in thermoplastic starch/polyester blown films

). The films were characterised for their mechanical, structural and barrier properties. Increasing fibres concentration reduced the tensile strength (6.9 to 4.6 MPa), the elongation at break (568 to 147%) and weight loss in water (12.8 to 11.1%) of the films. The rigidity of the films increased from 19.8 MPa (without MCC) to 79.2 MPa in the samples with 10 g.100 g