Multifunctional Characteristics of Glass Fiber-Reinforced Epoxy Polymer Composites with Multiwalled Carbon Nanotube Buckypaper Interlayer

In this work, multiwalled carbon nanotube buckypaper (MWCNT-BP) was inserted at the middle-plane of glass fiber/epoxy resin prepregs to obtain three-phase nanostructured composite. Preliminary tests conducted by differential scanning calorimetry and thermogravimetric analyses (TGA) revealed that the proposed curing cycle to prepare the laminates in a hot compression-molding machine was appropriated. The mechanical properties of the BP-based composite studied by short beam shear and compression shear tests presented no improvements compared to the base laminate. On the other hand, the thermal properties of the nanostructured composite improved as demonstrated by dynamical mechanical analyses and TGA. Besides, the reflectivity results revealed an average value of −12.2 dB in the X-band with a maximum attenuation of 99.4% of the incident wave at 9.5 GHz. The improvements in both thermal and electromagnetic properties demonstrate the potential for both structural and multifunctional applications of the obtained BP-composite. POLYM. ENG. SCI., 60:740–751, 2020. © 2020 Society of Plastics Engineers     

Flame-retardant properties of phenol–formaldehyde-type resins and triphenyl phosphate in styrene–acrylonitrile copolymers

The thermal and flame-retardant properties of phenol–formaldehyde-type resins (crosslinked and noncrosslinked) in mixtures with triphenyl phosphate and styrene–acrylonitrile resins were evaluated. The mixtures show a synergistic effect between triphenyl phosphate and novolacs. Those containing phenol–formaldehyde novolac resins are found to be most flame retardant. There does not seem to be a relationship between the oxygen index (OI) and UL 94 tests. Scanning electron microscopy analysis show a surface structure with cavities and stratification, very similar to that of intumescent additives. Evidence was found indicating that this flame-retardant system works in both the gas and condensed phase. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1067–1076, 1998     

Blends of polyamide 6, polycarbonate,and poly(propylene oxide). I. Reactive compatibilization–morphology relationships

The relationship between reactive compatibilization and morphology of the polyamide 6–polycarbonate (PA6–PC) and polyamide 6–polycarbonate–poly(pro-pylene oxide) (PA6–PC–PPO) blends were investigated by means of torque values, scanning electron microscopy, and Fourier transform infrared spectroscopy. The micrographs show that the blends processed for a long period of time presented a PC domain of smaller size and better adherence between the phases than the blends processed for a short period of time. This fact can be related with the presence of the block copolymer of PA6–PC synthesized in situ by the reaction of PA6 and PC and depend on temperature and mixing time. The presence of PPO does not impede the formation of copolymer but interferes on the size of the domain. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 857–864, 1998     

Development of active cassava starch cellulose nanofiber-based films incorporated with natural antimicrobial tea tree essential oil

In the present study, a cassava starch-glycerol film with reinforcement of Pinus sp. nanofibers (NFC) incorporated with tea tree (Melaleuca alternifolia) essential oil (TTO) were prepared by casting technique. The physical (barrier, mechanical, and optical), structural, and antimicrobial properties of the films were evaluated and compared with the control films. Films with 0.08% TTO exhibited a significant increase in the tensile strength (TS) while films with 1.5% TTO showed a decrease in TS, suggesting a crosslinking effect. The addition of 1.5% TTO reduced the water vapor permeability values in 43% comparing to the control films. Analysis obtained by Fourier transform infrared spectroscopy showed bands related to the interaction between TTO and matrix for films with 1.5% TTO and 0.3% NFC. This film was effective against Staphylococcus aureus and Candida albicans which could be applied for several packaging purposes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48726.     

Fibre optic probe measurements in landrace pigs of different halothane phenotypes

Fibre Optic Probe (FOP) measurements were made in the longissimus dorsi muscle of 70 halothane-positive (HP) and 70 halothane negative (HN) pigs of a synthetic Landrace strain at 45 min (FOP(1)), 3 h (FOP(3)) and 17h (FOP(17)) post mortem. Measurements of pH, rigor and temperature were also made in the slaughterline. Carcasses were sampled (longissimus dorsi, 2-4 lumbar vertebrae) at 18h post mortem and meat quality objectively assessed. The incidence of slight PSE (visual score) was 49% in HP and 10% in HN pigs, while the incidence of serious PSE was 20% and 4%, respectively. Yet, the percentage drip loss during 48 h storage in HN/PSE pigs was higher than in HP/PSE pigs (10·2 vs 7·5%), which was associated with a lower ultimate pH (5·25 vs 5·44). Therefore, it is suggested that the remaining PSE problem in HN Landrace pigs, although less in frequency, might be more serious. In the whole population, of all FOP measurements taken correlations with colour (Hunter L(?)-value) and percentage drip loss were highest for the FOP(17) measurements (r = 0·82 and 0·69, respectively). FOP(1) was better related than pH(1) to colour, while the relationships with drip loss were of a similar magnitude. Differences in FOP values between HP and HN pigs were larger for FOP(1) (148 vs 108) than for FOP(3) (148 vs 125) or FOP(17) (153 vs 130). The relationship between FOP1 and ultimate meat colour (L(?)-value) appeared to be higher in HP (0·60) than in HN (0·48) pigs, while for the relationship between FOP(1) and percentage drip loss the reverse was true (0·48 and 0·60, respectively). The effect of halothane phenotype on the relationships found, may partially explain the different results of reflectance measurements reported in the literature as to their predictive value for ultimate meat quality. The results suggest that the measurement of reflectance in the slaughterline offers opportunities for identifying (potential) PSE carcasses. The large genetic influence of halothane phenotype on this parameter, may eventually justify its use as a base for payment for meat quality to the producer.     

Xylitol as a Hydrophilization Moiety for a Biocatalytically Synthesized Ibuprofen Prodrug

Biocatalyzed synthesis can be exploited to produce high-value products, such as prodrugs. The replacement of chemical approaches with biocatalytic processes is advantageous in terms of environmental prevention, embracing the principles of green chemistry. In this work, we propose the covalent attachment of xylitol to ibuprofen to produce an IBU-xylitol ester prodrug. Xylitol was chosen as a hydrophilizer for the final prodrug, enhancing the water solubility of ibuprofen. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) extensively used as an analgesic, anti-inflammatory, and antipyretic. Despite being the third-most-prescribed medicine in the world, the aqueous solubility of ibuprofen is just 21 mg/L. This poor water solubility greatly limits the bioavailability of ibuprofen. We aimed to functionalize ibuprofen with xylitol using the reusable immobilized N435 biocatalyst. Instead of a biphasic media, we proposed a monophasic reaction environment. The characterization of the IBU-xylitol ester was performed by ¹H, ¹³C-NMR, DEPT, COSY, HMQC, HMBC, FTIR, and MS spectroscopy. Preliminary in vitro tests showed that this enzymatically synthesized prodrug of ibuprofen reduced the expression of the interleukin 8 genes in human bronchial epithelial cells (IB3-1) from cystic fibrosis (CF) patients.     

Gamma Irradiation of in-Shell and Blanched Peanuts Protects against Mycotoxic Fungi and Retains Their Nutraceutical Components during Long-Term Storage

Peanut samples were irradiated (0.0, 5.2, 7.2 or 10.0 kGy), stored for a year (room temperature) and examined every three months. Mycotoxic fungi (MF) were detected in non-irradiated blanched peanuts. A dose of 5.2 kGy was found suitable to prevent MF growth in blanched samples. No MF was detected in in-shell peanuts, with or without irradiation. The colors of the control in-shell and blanched samples were, respectively, 44.72 and 60.21 (L *); 25.20 and 20.38 (Chroma); 53.05 and 86.46 (°Hue). The water activities (Aw) were 0.673 and 0.425. The corresponding fatty acids were 13.33% and 12.14% (C16:0), 44.94% and 44.92% (C18:1, ω9) and 37.10% and 37.63% (C18:2, ω6). The total phenolics (TP) were 4.62 and 2.52 mg GAE/g, with antioxidant activities (AA) of 16.97 and 10.36 μmol TEAC/g. Storage time negatively correlated with Aw (in-shell peanuts) or L *, linoleic acid, TP and AA (in-shell and blanched peanuts) but positively correlated with Aw (blanched peanuts), and with oleic acid (in-shell and blanched peanuts). Irradiation positively correlated with antioxidant activity (blanched peanuts). No correlation was found between irradiation and AA (in-shell samples) or fatty acids and TP (in-shell and blanched peanuts). Irradiation protected against MF and retained both the polyunsaturated fatty acids and polyphenols in the samples.     

Evaluation of the corrosion behavior of galvannealed steel in chloride aqueous solution and in tropical marine environment

An investigation was made into the corrosion behavior of commercial galvannealed steel in 10⁻² mol dm⁻³ NaCl aqueous solutions and in a tropical marine environment, using scanning electron microscopy (SEM), galvanostatic electrochemical stripping (GES), potentiodynamic linear polarization (PLP), and electrochemical impedance spectroscopy (EIS) techniques and open circuit measurements (E _oc). For purposes of comparison, a commercial galvanized steel was also subjected to similar corrosion tests. GES and SEM techniques allowed for the identification of ζ, δ and Γ intermetallic phases and revealed cracks in the galvannealed steel. The PLP, EIS and E _oc results indicated that the galvannealed coating was more corrosion resistant than galvanized coating in an aqueous medium, but that their corrosion behaviors were similar in the marine environment. The corrosion behavior of the galvannealed steel was affected by the evolution of the cracking process in the Zn–Fe layer due to the dissolution of zinc-rich phases, while the galvanized steel displayed generalized corrosion in the aqueous medium and localized corrosion in the marine environment.     

Polymer electrolytes based on poly(ethylene glycol) dimethyl ether and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate: Preparation, physico-chemical characterization, and theoretical study

Polymer electrolytes based on poly(ethylene glycol) dimethyl ether (PEGdME) and the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF₆) have been prepared and characterized by different techniques. Coordination of the IL by the polymer occurs mainly in the amorphous phase. This finding was correlated with previous theoretical investigations of a similar model for polymer electrolytes based on poly(ethylene oxide), PEO, and IL. It has been obtained ionic conductivity σ ∼ 10⁻³ S cm⁻¹ for the polymer electrolyte with 35 wt% of IL at 100 °C. The same order of magnitude for σ was obtained by molecular dynamics simulation of PEO/IL. This work demonstrates consistency between experimental and theoretical results for polymer electrolytes containing ionic liquids.