Abstract Polymer materials (plastics and elastomers) are widely used in applications involving ionizing radiation environmental exposure. Such rush in service conditions might promote significant material degradation. Here, we investigated gamma irradiation effects on poly(ethylene-co-vinyl acetate) (EVA) (25 and 40 wt% vinyl acetate - VA) in the dose range of 5 – 30 kGy. This range is suitable for applications in food preservation and matches expected absorbed doses for nuclear power plants electrical cables and wires. EVA copolymers with 40 or 25 wt% VA predominantly underwent crosslinking effects promoted by gamma irradiation at dose of 10 kGy. Additional irradiation of EVA (25% VA) up to 30 kGy did not promote further alterations. Refractive index or thermal degradation under nitrogen atmosphere remained practically unaltered after gamma irradiation. Our findings suggest that EVA is a suitable material for irradiated food packaging films, and in electrical cable jacketing materials exposed to gamma radiation.

Abstract Single-use plastics represent almost a fifth of the global plastics market, leading to high residual accumulation. The study aimed to evaluate the biodegradability, under anaerobic conditions, of additivated polyethylene terephthalate (PET-ad), marketed by a company in Brazil. The polymeric films were submerged in digesters in sludge from sewage treatment plants. Films were characterized throughout time, as were the biogas and microorganisms in the medium. The results indicated weight and microscopic differences attributed to sludge components and microbial colonization on films’ surfaces. The thermal properties did not show changes. Moreover, at the end of the research, the microorganisms still had considerable concentration – 106 and 109 NMP/ml, anaerobic and aerobic, respectively. The production of methane (60% v/v) and carbon dioxide (30% v/v) gases peaked in the first month and decreased subsequently. At eighteen months, PET-ad has been proven to undergo the initial degradation process faster than negative control.

Abstract In this work, a study was undertaken to explore the possibility of using leftover tamarind fruit fibres as reinforcement in PLA and HDPE matrix. PLA and HDPE polymers form minimum 75% of the total polymers used in the composites. PLA and HDPE was mixed with natural fibres (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%,) individually and also as a hybrid filler to enhance its mechanical properties. Characterizations, mechanical behaviour and microscopic investigation were performed to understand the excellent mechanical properties and good chemical resistance of the prepared composites, which demonstrated potential suitability for semi-structural applications.

Abstract Using ternary blends is a technological solution to combine the best characteristics of different elastomers. Quantifying rubbers in a blend, in which each content influences the result, is a task complex and usually requires the coupling of techniques. Therefore, it is necessary to develop simple, fast and accurate methodologies for this purpose. This study presents the analysis of polychloroprene, poly-cis-isoprene and polybutadiene (CR/NR/BR) rubber, with the selection of bands A1116 (CR), A2960 (NR) and A738 (BR), by universal attenuated total reflection (UATR) infrared spectroscopy performed on the sample as received. The error found was 2%, with 98 to 99% of the data explained by the methodology. The methodology responds more adequately to CR and BR cis, but has the ability to detect up to 5% of NR and 10% of CR and BR. Acid-resistance data are used quantitatively in the determination of BR rubber, satisfactorily confirming the spectral data found.

Abstract Hot melt adhesives based on blends of poly (ethylene-co-vinyl acetate), (EVA), and thermoplastic starch modified with citric acid (TPS), compatibilized with polyolefin grafted with maleic anhydride (PO-g-MA) were prepared. The materials were characterized by scanning electron microscopy (SEM) of fragile fractured surface, rotational viscosimeter (Brookfield) and FTIR. SEM showed interfacial failure in non-compatibilized blends and a decrease in the size of TPS dispersed phase as compatibilizer is added. When adding 5 and 7% of the compatibilizer, results from the viscosimeter indicated increase of 85% and 109% in viscosity, respectively. FTIR showed a dislocation in the absorption of hydrogen bands and ester linkages. These results indicated the effectiveness of the polyolefin functionalized. In performance analysis, compatibilized blends with 25% TPS, exhibited greater adhesion compared to standard hot melt adhesive at low application temperature (140°C), which demonstrates great potential for natural materials in adhesive’s industry.

Abstract This work aimed to develop biodegradable films from yellow passion fruit (Passiflora edulis f. flavicarpa) peel flour. The Central Composite Rotational Design was used in a total of 11 tests, in which the independent variables were the concentrations of starch and glycerol, characterized with regard to physical, mechanical and barrier properties. The films were classified as soluble and showed low permeability to water vapor. The tensile strength, elastic modulus and deformation rate were directly related to the concentration of starch and glycerol. The film of test 7 had the best characterization results; therefore, it was analyzed for biodegradability. As for biodegradability, the film obtained an average mass loss of 92.77 ± 4.28%, being a great alternative to the use of non-biodegradable polymers. The films showed acceptable degree of plasticization, which was favored by intermolecular interactions between the components of the flour, starch and glycerol.

Abstract This study aimed to investigate the therapeutic potential of a nanoparticle formulation containing the immunodominant peptide SSIEFARL from Herpes simplex virus 2 glycoprotein B A against genital herpes. A nanoparticle formulation (NanoSSIEFARL) was engineered and characterized for its physicochemical and immunomodulatory properties. NanoSSIEFARL displayed mean particle size of 212 ± 5 nm, polydispersity index of 0.12 ± 0.01 and zeta potential of -7.4 ± 2.5 mV, exhibiting spherical morphology. pH stability remained consistent over 30 days (day 0: 4.5 ± 0.5; day 30: 5.0 ± 0.5). A novel high-performance liquid chromatography method was validated for SSIEFARL quantification. Peptide association efficiency reached 98.3% ± 2.1, with 41.6% ± 4.4 peptide release from nanoparticles after 4 hours. Cytotoxicity assessment revealed cellular viability exceeding 90%, with macrophage uptake observed after 4 hours. Altogether, these results suggest that NanoSSIEFARL is a promising candidate for effective immunotherapy against genital herpes.

Abstract A novel conjugated rod–coil diblock copolymer poly(3-hexylthiophene)-block-poly(furfuryl methacrylate) (P3HT-b-PFMA) has been successfully synthesized for the first time using photoinduced organocatalyzed atom transfer radical polymerization (O-ATRP). This process utilized an organic photoredox catalyst of N-aryl phenoxazine, namely 10-(Perylene-3-yl-10H-Phenoxazine, under 365 nm UV irradiation. The diblock copolymer P3HT-b-PFMA was produced efficiently in a controlled manner, resulting in designed average molecular weights and a narrow polydispersity index. Notably, the furfurylmethacrylate (FMA) monomer derived from biomass-based furfuryl compounds was applied for this controlled polymerization, leading to the formation of conjugated diblock copolymers. The synthesized P3HT-b-PFMA was characterized through 1H-NMR, FT-IR, and GPC methods. Furthermore, the optical and hydrophilic-hydrophobic properties of P3HT-b-PFMA were also evaluated through UV-Vis spectroscopy and contact angle measurements.

Abstract Fossil-origin plastics have raised great concerns due to their non-biodegradable nature. Biodegradable polymers can be an alternative for these materials’, however they have higher cost. The use of agro-industrial waste in blends with biopolymers can provide cheaper materials’ with improved properties. This study aims to develop low-cost biodegradable materials by extrusion and thermoplastic injection using oat hulls, polybutylene succinate (PBS), and starch. Six formulations with different concentrations of oat hulls (0-56% w/w) were extruded in a single-screw extruder, and then the materials were produced by thermoplastic injection. The extrusion aligned the oat hull fibers, making the material dimensionally stable. The oat hulls enhanced stiffness and reduced material density compared to non-hull counterparts. Besides that, the oat hulls are a low-cost agro-industrial byproduct, and it was possible to produce biodegradable materials with up to 56% hulls and only 20% PBS. These biodegradable materials are environmentally friendly and non-toxic.

In this study, thyme essential oil was added to poly (butylene adipate-co-terephthalate) (PBAT) films in a variety of compositions (0, 1, 2, 5, 10, 15, and 20% w/w), and the effect of the essential oil on the PBAT's characteristics was evaluated. The films were produced using the casting technique. Thyme essential oil (EO) was evaluated by mid-infrared, gas chromatography-mass spectrometer, and antimicrobial activity. The films were evaluated by mid-infrared, mechanical, and thermal tests. The results demonstrated that EO has a higher concentration of o-cymene and antimicrobial activity against the bacteria Escherichia coli and Staphylococcus aureus. The films were analyzed for their mechanical and thermal properties according to the compositions tested. The films have shown promise for use as active packaging.