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Polymeric films containing pomegranate peel extract (PPE) can act as a drug-delivery platform for topical treatment of candidiasis. The composition, mechanical resistance, and in vitro antifungal activity of a polymeric film containing PPE at 1.25 mg.mL-1 were investigated. Films were prepared using a solvent casting technique. The incorporation of PPE in the polymeric matrix gave rise to homogeneous, smooth, shiny, and yellowish-brown films. FTIR spectra of the film containing PPE showed differences without compromising the stability of the extract and the matrix. SEM analysis showed the existence of interruptions in the continuity of the films with extract, which promoted a reduction in the mechanical parameters without significantly changing the tensile strength and elongation at break. Films showed adequate mechanical properties and antifungal activity against Candida albicans, C. glabrata, C. krusei and C. tropicalis.

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Natural lignocellulose fibers have been extensively investigated and applied as a reinforcement of polymer composites in industrial applications from food packing to automotive parts. Among the advantages of natural fibers stands their relatively low cost and sustainable characteristics. These are accentuated in the case of residual fibers such as those obtained from coffee husks, an agribusiness waste, usually burnt or disposed into the environment. As composite reinforcement, hydrophilic natural fibers display adhesion problems to the most hydrophobic polymer matrices. This adhesion might be improved with distinct types of fibers surface treatments. In the present work, the effectiveness of three surface treatments applied to coffee husk fiber wastes (CHFW) were investigated, aiming to improve the tensile performance of castor oil-based polyurethane (COPU) biocomposites. The effects of treatments associated with (i) chemical with sodium hydroxide, (ii) physical by temperature and pressure and hydrothermic treatment, and (iii) biological by fermentation with Phanerochaete Chrysosporium fungus were evaluated by means of Fourier transformed infrared spectroscopy, X-ray diffraction, thermal analyses and morphology by scanning electron microscopy for different concentration of NaOH, different hydrothermic times at 121 °C/98 kPa and exposition to P. chrysosporium. The most effective treatment was the hydrothermal one at 121 °C and 98.06 kPa for 30 min. Preliminary tensile tests were performed in COPU biocomposites reinforced with 20% CHFWs subjected to the optimized conditions for each distinct type of treatment. The results indicated that the hydrothermal treatment promoted significant enhancement in the fiber/matrix interfacial bond, increasing the tensile strength up to 60% compared to COPU reinforced with in natura CHFWs fibers. It is important to mention that these composites can be applied as plastic wood for household items' internal parts and in the automobile industry.

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In a recent paper, novel polyester nanocomposites reinforced with up to 3 wt% of cellulose nanocrystals (CNCs) extracted from conifer fiber were characterized for their crystallinity index, water absorption, and flexural and thermal resistance. The use of this novel class of nanocomposites as a possible substitute for conventional glass fiber composites (fiberglass) was then suggested, especially for the 1 and 2 wt% CNC composites due to promising bending, density, and water absorption results. However, for effective engineering applications requiring impact and tensile performance, the corresponding properties need to be evaluated. Therefore, this extension of the previous work presents additional results on Izod and tensile tests of 1 and 2 wt% CNC-reinforced polyester composites, together with a comparative cost analysis with fiberglass. The chemical effect caused by incorporation of CNCs into polyester was also investigated by FTIR. In comparison to the neat polyester, the Izod impact energy increased 50% and 16% for the 1 and 2 wt% composites, respectively. On the other hand, the tensile strength and Young's modulus remained constant within the ANOVA statistical analysis. FTIR analysis failed to reveal any chemical modification caused by up to 2 wt% CNC incorporation. The present impact and tensile results corroborate the promising substitution of a polyester composite reinforced with very low amount of CNCs for common fiberglass in engineering application.

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The application of cellulose nanocrystal has lately been investigated as polymer composites reinforcement owing to favorable characteristics of biodegradability and cost effectiveness as well as superior mechanical properties. In the present work novel nanocomposites of unsaturated polyester matrix reinforced with low amount of 1, 2, and 3 wt% of cellulose nanocrystals obtained from conifer fiber (CNC) were characterized. The polyester matrix and nanocomposites were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), bending test, and thermogravimetric analysis (TGA). The result showed that the addition of only 2 wt% CNC increased the nanocomposite flexural strength by 159%, the ductility by 500% and the toughness by 1420%. Fracture analyses by SEM revealed a uniform participation of the CNC in the polyester microstructure. The resistance to thermal degradation of the CNC reinforced nanocomposites was improved in more than 20 °C as compared to neat polyester. No significant changes were detected in the water absorptions and XRD pattern of the neat polyester with incorporations up to 3 wt% CNC. These results reveal that the 2 wt% CNC nanocomposite might be a promising more ductile, lightweight and cost-effective substitute for conventional glass fiber composites in engineering applications.

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Chronic wounds constitute a serious public health problem, and developing pharmaceutical dosage forms to ensure patient comfort and safety, as well as optimizing treatment effectiveness, are of great interest in the pharmaceutical, medical and biomaterial fields. In this work, the preparation of films based on blends of poly(vinyl alcohol), starch and poly(acrylic acid), polymers widely used as pharmaceutical excipients, and pomegranate peel extract (PPE), a bioactive compound with antimicrobial and healing activities relevant to the use as a bioactive wound dressing, was proposed. Initially, the minimum inhibitory concentration (MIC) of the PPE was investigated by an in vitro method. Then, the best concentration of the PPE to be used to prepare the films was researched using an antimicrobial susceptibility test with the disc diffusion method. The microbiological assay was performed in films prepared by the solvent casting method in the presence of two concentrations of PPE: 1.25% w/v and 2.5% w/v. Films containing the lower PPE concentration showed antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis, with a difference that was not considered statistically significant when compared to the higher concentration of the extract. Therefore, the films prepared with the lower proportion of PPE (1.25% w/v) were considered for the other studies. The miscibility and stability of the extract in the films were investigated by thermal analysis. Parameters that determine the barrier properties of the films were also investigated by complementary techniques. Finally, in vitro biological tests were performed for safety evaluation and activity research. Analysis of the results showed that the incorporation of the higher proportion of starch in the blend (15% v/v) (PVA:S:PAA:PPE4) yielded smooth, transparent, and domain-free films without phase separation. Additionally, the PVA:S:PAA:PPE4 film presented barrier properties suitable for use as a cover. These films, when subjected to the in vitro hemolytic activity assay, were nonhemolytic and biocompatible. No toxicity from the extract was observed at the concentrations studied. The results of the wound healing in vitro test showed that films containing 1.25% PPE are efficient in reducing the scratch open area, provoking almost total closure of the scratches within 48 h without cytotoxicity.

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