Abstract Poultry litter waste (PLW) is the main by-product generated by the Brazilian poultry industry. A sustainable approach for reusing this waste is the production of biochar to be further used aiming CO2 adsorption. In this work, biochars were produced by varying the N2 flow along the pyrolysis process of 150 (PLW-150) and 1000 (PLW-1000) mL min-1. PLW and biochars were characterized for their morphology, porosity, specific surface area, and CO2 adsorption capacity. From the biochars, carbon cryogels (CC) were produced aiming their use as CO2 adsorbents. The results of the cryogel adsorption test showed a CO2 adsorption capacity of 13.1±2.9 and 33.8±3.3 mg g-1 for the CC-PLW.150 and CC-PLW.1000 cryogels, respectively. Therefore, reusing this residue for cryogels production and its use in the CO2 adsorption signifies an attractive perspective to minimize the environmental damage caused by CO2 emissions.

Abstract Nanocellulose (BNC) is a natural polymer produced by bacteria. Its structure has only glucose monomer, it has various properties such as high water holding capacity, unique nanostructure, high crystallinity and high mechanical strength. Pure BNC or in combination with different components can be used for a wide range of applications. Aloe vera is a medicinal plant with polysaccharides in its composition that has a potential for tissue regeneration and repair. The aim of this study was to evaluate the effect of incorporating Aloe vera (A. vera) into BNC membranes produced with three fractions of A. vera extract (BNC-Aloe) on the behavior of epithelial cells. Human fibroblasts and keratinocytes were shown to have increased metabolic activity and proliferation when cultured on BNC-Aloe membranes compared to control. Quantification of collagen biosynthesis was significantly higher in BNC-Aloe membranes. In conclusion, BNC-Aloe membranes are suggested as a material for the purpose of skin tissue repair.

Abstract The strategy of combining the traditional reinforcement of glass fibers (GF) with lighter hollow glass microspheres (HGM) can afford to fulfill the need for potential light-weight and high-strength modern materials required in various sectors, such as automotive and aerospace industry applications. This work fabricated composites of PA6/GF/HGM by melting blending in a co-rotating twin-screw extruder, and subsequently, injection molded. The effects of HGM content on the density, morphological and mechanical properties were investigated and the PA6/GF/HGM composites properties were compared to the properties of the traditional PA6/GF (70/30) wt% composite, widely used today in automotive industries. With the increase of HGM amount in the formulations, a reduction of between 3 and 12% in density was achieved with a slight reduction in its mechanical properties, showing that this new strategy can be applied to replace the PA6/GF (70/30) wt% composite, providing a considerable weight reduction for these materials.

Abstract To analyze the biocompatibility of the scaffold produced from a natural polymer derived from castor oil through hemolytic activity and antimicrobial activity, to enable the clinical application. Three in vitro tests were performed: Hemolytic activity test - Polymer partially dissolved in contact with blood agar; Hemolytic activity test in sheep's blood - Polymer extract with red blood cells solution; Antimicrobial activity test - Solid polymer in direct contact with E. Coli and S. Aureus. For hemolytic tests, none of the samples showed hemolysis. Negative hemolytic activity is a good indicator, as the maintenance of the blood clot in the area of the lesion is essential for the formation of new tissue. For the antimicrobial activity test, no significant activity was observed against the bacteria used. The polymer is not toxic to red blood cells, being viable for clinical application as a matrix for tissue regeneration.

Abstract The lack of knowledge about the behavior under creep and fatigue limits the use of polymeric composites reinforced with natural fibers. Thus, this work assessed the behavior of epoxy composites reinforced with sisal fibers under tensile, fatigue, and creep tests. Also, thermogravimetry and scanning electron microscopy assessed the sodium hydroxide (NaOH) treatment efficiency in sisal fibers. Further, differential scanning calorimetry determined the degree of cure of the composites, and stereomicroscopy allowed the evaluation of the surface’s fracture. As a result, the tensile strength of the composite was 1.4 times the value of neat epoxy resin after 100,000 cycles in the fatigue test. Moreover, when loaded with 20% of the maximum tensile strength, it is estimated that the composite resists 200,000 h without rupturing by creep. To conclude, the efficient adhesion between sisal fibers and epoxy obtained by NaOH treatment allowed good mechanical behavior to the epoxy composite.

Abstract Cellulose nanocrystals (CNCs) can improve the mechanical properties of dental resins. However, there is a deficiency of information about the behavior of physical properties of resins after this addition. The purpose was to evaluate the characterization and physical properties of hard chairside reline material modified with CNCs (0.25%, 0.5%, 0.75% or, 1.0%). Addition of CNCs at 0.5%, 0.75% and 1% increased Vickers hardness; 0.75% decrease surface free energy; 0.75% and 1% showed similar to control on the surface roughness. The simple and straightforward approach of adding CNCs, a renewable material, provides good potential for its future practical application as it has shown promise with increasing hardness. It means that the incorporation of CNCs into this denture reline resin could improve the abrasion resistance of this material, which is desirable in the long term.

Abstract In this study, the leaching performance of boron compounds from Oriental beech (Fagus orientalis L.) wood coated with polyurethane/polyurea (PUU) hybrid resin and epoxy resin (EPR) was investigated. Leaching of boron test and SEM (Scanning Electron Microscopy) analyzes were applied to the prepared test specimens. According to the leaching of boron test results, specimens coated with polyurethane/polyurea (PUU) hybrid resin gave the most positive result against boron leaching. It was found that boric acid (BA) impregnated and epoxy resin (EPR) coated Oriental beech wood showed a smoother surface than other treatment groups.

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 Kafirins, water-insoluble proteins from Sweet Sorghum BR501 grains, have been an alternative to prepare edible coatings for food due to their hydrophobic character. In this work, the secondary structures (SS) content of reduced (SSr) and unreduced (SSu) kafirins were determined by 13C solid-state-NMR spectroscopy using areas of carbonyl peak. The SS elucidate by fitting the signal with the Lorentzian function shows 56% and 59% of α-helix and 40% and 12% of β-sheet structures for SSr and SSu, respectively. The SS also were elucidated by a Singular value decomposition- SVD method shows 55% and 49% of α-helix and 12% and 8% of β-sheet structure for SSr and SSu, respectively. Since SVD does not depend on the operator and has higher correlation coefficients for α-helix (0.96%) and β-sheet (0.91%), it is a reliable method to quantify the SS of insoluble proteins using the 13C NMR signal.

Abstract In the research, sea mussel shell (Chamelea gallina) powders were impregnated on the samples of Eastern spruce (Picea orientalis (L.) Link.) and Anatolian chestnut (Castanea sativa Mill.) by dipping method at different concentrations (1%, 5%, 10%, 15%). To investigate the level of use in the wood industry and especially its effects against fire; adhesion, thermogravimetric analysis (TGA), limiting oxygen index (LOI) test measurements were carried out. According to the TGA results, while the residue quantity in the spruce wood sample was the highest at 5%, the residue amount in the chestnut wood sample was the highest at 15%. With increasing amounts of mussel shell powder, the limiting oxygen index values in both wood species samples increased. As a result, it was discovered that impregnating wood samples with mussel shell powder improved the wood's fire resistance.

Abstract This study evaluated the influence of non-thermal argon plasma applied to dentin on the shear strength of two adhesive systems. Ninety tooth fragments were embedded in epoxy resin and distributed into experimental groups (n=15): G1 and G4 - adhesive systems applied according to the manufacturers’ instructions; G2 and G5 - dentin treated with non-thermal argon plasma for 30 seconds before hybridization; G3 and G6 - dentin treated with non-thermal argon plasma for 30 seconds after hybridization. Cylinders were made with composite resin in the adhesive area, and the specimens were submitted to the shear strength test. Higher values were observed when applying the plasma treatment after hybridization (G1: 26.51 MPa, G2: 29.22 MPa, G3: 30.27 MPa, G4: 22.66 MPa, G5: 28.33 MPa, G6: 29.32 MPa). The treatment with non-thermal argon plasma significantly increased the shear strength values regardless of the application time.

Abstract Cross-link density impacts most mechanical properties of rubber, therefore it is necessary to have a method to measure it. The most widely used method is via equilibrium swelling, however, it is time consuming and uses organic solvents. Dynamic Shear Test (DST) can be used to calculate both chemical and physical cross-links in rubber compounds in shorter times than by swelling equilibrium method, and without the use of solvents. In this work, equilibrium swelling using toluene and acetone was used to validate the dynamic shear tests for different nitrile rubber (NBR) compounds. The DST had a good correlation with the swelling equilibrium method using acetone, with a correlation coefficient of ~0,91, validating the use of DST. Moreover, the use of the Modified Guth-Gold equation (instead of Guth-Gold Equation with Medalia correction) also allowed to deduct the effect of carbon black on the cross-link density from the DST.

Abstract This work presents an alternative to studying and determining the torsion modulus, G, in composites. For this purpose, we use a measuring system with a rotation motion sensor coupled with a torsion pendulum that allows for determining the angular position as a function of the time. Then, through an equation derived from mechanical spectroscopy studies that permits the calculation of G’s value, the experiments focus on samples of different quantities of calcium carbonate (CaCO3) in unsaturated polyester resins. The results show that CaCO3 (33.33%W) fillers increase G’s value by 88% compared with unsaturated resin (100%W). Furthermore, there is a density increase of approximately 21% with the addition of CaCO3, considering the same two samples, which makes these composites the most massive. The relationship between G and composite density shows that it is possible to change the amount of CaCO3 to increase torsion resistance values in a controlled way.

Abstract This study aimed to focus on classifying rubber foam grades according to ASTM D1056. The natural rubber foams were prepared by varying the Azodicarbonamide (ADC) content from 2 - 10 phr. The results were evaluated on their physical and mechanical properties. The relative foam density of the foams decreased, and the expansion ratio increased with the addition of ADC. This was due to the increase in the gas phase raised by ADC. In addition, adding ADC also decreased hardness and compression-deflection of the foams, whereby the values obtained were higher after oven aging due to the radical recombination caused by chain breaking. According to ASTM D1056, the compression-deflection values of the foams were 2A2 and 2A3 grades, where the ADC content at 6 – 10 phr met the basic properties required by the same standard. Furthermore, the ADC content at 6 phr is strongly suggested when considering the foam morphology.

Abstract Hybrid composites were prepared using recycled polypropylene (rPP), dimension stone waste (Bege Bahia, BB) and coconut fiber (CF). Post-consumer the formulations of rPP/BB/CF and virgin PP, were processed in a Haake mixer. The films were characterized according to chemical, physical and mechanical properties. Multiple linear regression tests were used to develop mathematical models, which allow simulating the behavior of the composition of composite on mechanical properties. Density variations were associated with differences in particle packing and particle wall roughness. The impact resistance of rPP/BB/CF was slightly higher in the 70/10/20 wt% composite. SEM micrographs of the ternary (70/20/10 wt%) showed stronger traces of decohesion, allowing higher water absorption and reducing impact resistance. The response surface methodology suggest that the increase in the variable “coconut fiber content” is responsible for improving the mechanical properties of the composite. The ternary composite (70/10/20 wt%) was best for replacement of virgin PP.