Characterization of Food Packaging Films with Blackcurrant Fruit Waste as a Source of Antioxidant and Color Sensing Intelligent Material

Chitosan and pectin films were enriched with blackcurrant pomace powder (10 and 20% (w/w)), as bio-based material, to minimize food production losses and to increase the functional properties of produced films aimed at food coatings and wrappers. Water vapor permeability of active films increased up to 25%, moisture content for 27% in pectin-based ones, but water solubility was not significantly modified. Mechanical properties (tensile strength, elongation at break and Young’s modulus) were mainly decreased due to the residual insoluble particles present in blackcurrant waste. FTIR analysis showed no significant changes between the film samples. The degradation temperatures, determined by DSC, were reduced by 18 °C for chitosan-based samples and of 32 °C lower for the pectin-based samples with blackcurrant powder, indicating a disturbance in polymer stability. The antioxidant activity of active films was increased up to 30-fold. Lightness and redness of dry films significantly changed depending on the polymer type. Significant color changes, especially in chitosan film formulations, were observed after exposure to different pH buffers. This effect is further explored in formulations that were used as color change indicators for intelligent biopackaging.

Tailoring of Durable Conductive and UV-Shielding Properties on Cotton and Polyester Fabrics by PEDOT:PSS Screen-Printing

In the present study, cotton (Co) and polyester (PES) fabrics were screen-printed with a conductive poly3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS) printing paste along with a commercially-available screen-printing binder (SFXC) or waterborne polyurethane resin (WPU), in order to enhance wash and wear durability, and to improve some functional properties, without essentially influencing the physical–mechanical properties of the base material, as well as the introduced fabrics’ conductivity. The application of a conductive polymer coating reduced transmittance in the whole UV region drastically, indicating good UV-shielding ability in the treated fabrics. Moreover, the employed binders improved the fabrics’ protection against harmful solar UV radiation significantly, depending on the type of fibre and binder. Furthermore, the SFXC binder intensified the hydrophobicity of Co as compared to the WPU binder, and, on the other hand, WPU reduced the hydrophobicity of PES. Finally, the screen-printed fabrics were washed up to 20 cycles and rubbed up to 20,000 cycles, and characterised by means of mass loss determination and electrical resistivity measurement. Both binders enlarged polymer stability against the effect of washing and rubbing, depending on the number of cycles, the type and amount of employed binder, the type of fibres, and the thickness and uniformity of coatings.

Polymer Stability After Successive Mechanical-Degradation Events

Summary A key challenge in polymer-flood forecasting is the prediction of polymer stability far from the injector. Degradation may result from various mechanical-degradation events in surface facilities and at the wellbore interface, as well as possible oxidative degradation caused by the presence of oxygen and reduced transition metals. All these steps must be closely examined to minimize degradation and ensure propagation of a viscous polymer solution. In this paper, polymer solutions are pushed toward degradation rates that would be unacceptable for enhanced-oil-recovery applications to better understand the underlying physics. Multistep degradation events are induced in various geometries, such as capillaries, blenders, and porous media. For the geometries and range of polymer and salt concentrations investigated, degradation (as defined here) approaches an asymptotic value as the number of degrading events increases. An empirical normalization method is proposed, allowing superimposition of curves of viscosity loss vs. time across multiple possible geometries. The normalization procedure is applied to predict the extent of degradation during a field injection in which near-wellbore degradation occurs after degradation in surface facilities. We predict that degradation in the porous medium reaches a stable value after passing through approximately 6 mm of rock. Finally, degradation is proposed as a tool to probe the molecular-weight distribution and to narrow the polydispersity of polymers, which can be used for maximizing both viscosifying power and injectivity simultaneously.

Influence of Fillers on Polyvinyl Chloride Materials Thermal Resistance

Innovative materials and structures are analyzed in this paper. Multicomponent formulation of polyvinyl chloride materials containing various functional additives requires assessment of their influence on polymer stability while processing and operating. According to the nature, particulate fillers widely used in plasticized and liquid compositions based on polyvinyl chloride may have different impact on thermal resistance of materials. This paper presents the study of organic and nonorganic dispersed waist as filler in polyvinyl chloride formulation and determines key parameters of their influence on thermal resistance of composition. Polyvinyl chloride stabilization course by means of polyfunctional fillers-modifiers in different mechanisms, such as: chemical stabilization – chloride hydride acceptance, replacement of chlorine labile atom in polymer macromolecule, adjoining conjugated defective ethylenic bonds, recombination macroradicals and physical stabilization – chloride hydride sorbing, reduction of mechanical destruction by oiling, etc. have been considered. Contribution into stabilization course in various mechanisms depending on chemical nature, dispersion rate and mineral content of fillers is evaluated.