Silicone-geranium essential oil blend for long-term antifouling coatings.

This study explores the potential of geranium essential oil as a natural solution for combating marine biofouling, addressing the environmental concerns associated with commercial antifouling coatings. Compounds with bactericidal activities were identified by 13Carbon nuclear magnetic resonance (13C NMR). Thermogravimetric analysis (TGA) revealed minimal impact on film thermal stability, maintaining suitability for antifouling applications. The addition of essential oil induced changes in the morphology of the film and Fourier transform infrared spectroscopy (FTIR) analysis indicated that oil remained within the film. Optical microscopy showed an increase in coating porosity after immersion in a marine environment. A total of 18 bacterial colonies were isolated, with Psychrobacter adeliensis and Shewanella algidipiscicola being the predominant biofilm-forming species. The geranium essential oil-based coating demonstrated the ability to reduce the formation of Psychrobacter adeliensis biofilms and effectively inhibit macrofouling adhesion for a duration of 11 months.

High-performance acetosolv lignin-incorporated DGEBA cured with aprotic imidazolium-based ionic liquid: Polymerization, chemical, thermal and combustion aspects of the thermosetting materials.

The lignin valorization constitutes a chemical platform for several segments of chemical industry. The aim of this work was to evaluate the potential of acetosolv coconut fiber lignin (ACFL) as an additive to DGEBA, curing it using an aprotic IL ([BMIM][PF6]) and analyze the properties of the obtained thermosetting materials. ACFL was obtained by mixing coconut fiber with 90 % acetic acid and 2 % HCl at 110 °C during 1 h. ACFL was characterized by FTIR, TGA and 1H NMR. The formulations were fabricated by mixing DGEBA and ACFL at different concentrations (0-50 % wt.). The curing parameters and [BMIM][PF6] concentrations were optimized by DSC analyses. The cured ACFL-incorporated epoxy resins were characterized by gel content (GC), TGA, MCC and chemical resistance in different media. ACFL undergone a selective partial acetylation that favored its miscibility with DGEBA. High GC values were obtained at high curing temperatures and ACFL concentration. The crescent ACFL concentration did not affect the Tonset of the thermosetting materials significantly. ACFL has increased the resistance of DGEBA to combustion and different chemical media. ACFL has shown a great potential to be used as a bio-additive for enhancing the chemical, thermal and combustion properties of high-performance materials.

Mechanochemical Treatment in High-Shear Thermokinetic Mixer as an Alternative for Tire Recycling.

This publication highlights the use of a high-speed thermokinetic mixer as an alternative to recycling ground tire rubber (GTR) using mechanochemical treatment. The GTR initially had a gelled fraction of 80% and presented a reduction of up to 50% of gel fraction in the most intensive condition (5145 rpm, n2). The processing condition at the lowest speed (2564 rpm, n1) resulted in greater selectivity in chain scission (K~1). However, in the most intense processing condition (10 min to n2), more significant degradation was observed via random scission, reduction in the glass transition temperature, Tg (11 °C), increase in the soluble polymeric fraction, and a more significant reduction in the density of bonds occurs. The artificial neural network could describe and correlate the thermal degradation profile with the processing conditions and the physicochemical characteristics of the GTR. The n2 velocity resulted in the formation of particles with a smoother and more continuous surface, which is related to the increase in the amount of soluble phase. The approach presented here represents an alternative to the mechanochemical treatment since it can reduce the crosslink density with selectivity and in short times (1-3 min).

Development of fibrous PLGA/fibrin scaffolds as a potential skin substitute.

The aim of this study has been to fabricate a hybrid electrospun nanofibrous scaffold composed of poly(lactic-co-glycolic) acid (PLGA)/fibrin polymers to be used as a skin substitute and analyze its physical and biological properties. Fibrin was obtained from rat blood plasma, characterized and solubilized in formic acid. The final electrospinning solution concentration was 40% PLGA (w/v) and 1% fibrin (w/v). To improve spinnability, 3% PEG (w/v) was added. The scaffolds were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Water contact angle, maximum elongation, thermal stability, degree of swelling, blood compatibility, cytotoxicity and cell viability were analyzed. The characterization by SEM showed randomly oriented nanofibers with a mean diameter of 639.8 ± 241.8 nm for the PLGA/fibrin and 1051.0 ± 290.2 nm for the PLGA. FTIR spectra confirmed the presence of fibrin in the mats. Fibrin incorporation reduced the water contact angle from 118.9 ± 2.9 to 111.1 ± 2.8. The fibrin increased tensile strength and decreased elongation at break. The scaffolds demonstrated blood compatibility and fibrin incorporation improved cell adhesion and viability when direct and indirect MTT analyses were carried out. Thus, it can be concluded that the PLGA/fibrin mat is a promising material for use as a skin substitute.