Abstract Aiming to produce an antimicrobial dressing for wound healing applications, in this work Tea Tree oil (TTO) was incorporated into PHBV nanofibers by absorption. It was observed increase in the nanofiber diameter due to 5% TTO absorption efficiency, which also led to a 54% decrease in the contact angle. The releasing assay indicates a 6.8% oil release in the first 24 h – being probably the oil deposited at the polymer surface – followed by a minimal release at 48 h. The set of antimicrobial assays performed suggests the incorporation of TTO optimized the antimicrobial activity of the polymer for E. coli and C. albicans, while against S. aureus no significant difference was observed. The MTT assay showed no cytotoxicity of PHBV, but the incubation of L929 fibroblast cells with PHBV-TTO reduced cell viability. Overall, the PHBV nanofibers containing TTO present great potential as an antimicrobial dressing.

Abstract Among the engineering thermoplastics, poly(phenylene sulfide) (PPS) stands out for its excellent properties and mainly for processing at lower temperatures. The requirements requested by industries can be made by improving mechanical strength, weight reduction, and durable components by reinforcing the PPS matrix with fiberglass (FG) and carbon fiber (CF). This review intends to present the most current research related to the physical, mechanical, and thermal properties of PPS and the PPS/FG and PPS/CF composites most currently used by the aerospace, automotive, and energy industries. In addition to presenting the feasibility of mechanical and thermal recycling processes for PPS-based waste to reinsert a high market value thermoplastic into the industrial production cycle, thus contributing to the minimization of waste destined for landfills and incinerated or even improperly disposed of in the environment.

Abstract Antistatic packaging is a very important sector since the electrostatic discharge of electronic devices can damage and/or disable these products. In addition, it is essential to dispose of this packaging correctly. In this work, the synergistic effect of the addition of lignin and carbon black on the development of antistatic and biodegradable packaging was verified. In this study, PLA was mixed with lignin and carbon black and the composites were prepared using a high-speed thermokinetic homogenizer where the melting of the PLA and the blend with fillers occurred by friction. The composites were characterized by Izod impact tests, scanning electron microscopy, thermal properties, electrical characterization and biodegradation tests in garden soil. The results show that lignin is a great option to accelerate the biodegradation of PLA in the garden soil and the carbon black acts as an antistatic agent reducing the electrical resistivity of the composites.

In this study, chitosan hydrogels were produced with 0, 2, 4 and 6 wt% of cellulose nanocrystals (CNC) using hexahydrate zinc nitrate (Zn(NO3)2.6H2O) as a catalyst for chitosan crosslinking reaction. CNC´s size was estimated by dynamic light scattering (DLS) and surface charge by zeta potential. Hydrogels were characterized by rotational rheometer, swelling test, uniaxial compression test, in vitro degradation, scanning electron microscopy (SEM) and microtomography. Results showed that zinc nitrate and CNC addition did not influence mechanical properties, degradation, and morphology of the hydrogels. However, zinc nitrate decreased 36.54% of the gel time and 41.37% of the swelling degree, and increased the crosslinking degree of the chitosan hydrogels, proving not only its catalytic effect but also its participation in the crosslinking reaction. Porosity was slightly reduced after addition of zinc nitrate and incorporation of CNC. In the mechanism of crosslinking reaction, a competition between CNC and zinc nitrate was observed.

A compatibilizer agent was successfully produced by grafting maleic anhydride (MA) to poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) chains on a reactive processing by mechanical mixing, using a mixture of PHBV, MA and dicumyl peroxide (DCP) as initiator. The resulting PHBV grafted MA (PHBV-g-MA) was characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC), and its properties were compared to neat PHBV. FTIR showed an absorption band at 699 cm-1 for PHBV-g-MA, related to CH group of grafted anhydride ring. The initial thermal degradation temperature of the compatibilizer agent was reduced when compared to neat PHBV. DSC analysis showed that after grafting MA onto PHBV the crystallization temperature was about 20ºC higher than neat PHBV, and the degree of crystallinity was increased. GPC analysis showed that MA when grafted onto PHBV led to a reduction of molecular weight and polydispersity.