Heat-Affected Zone and Mechanical Analysis of GFRP Composites with Different Thicknesses in Drilling Processes.

This article presents a comprehensive thermomechanical analysis and failure assessment in the drilling of glass fiber-reinforced polymer (GFRP) composites with different thicknesses using a CNC machine and cemented carbide drill with a diameter of 6 mm and point angles of ϕ = 118°. The temperature distribution through drilling was measured using two techniques. The first technique was based on contactless measurements using an IR Fluke camera. The second was based on contact measurements using two thermocouples inserted inside the drill bit. A Kistler dynamometer was used to measure the cutting forces. The delamination factors at the hole exit and hole entry were quantified by using the image processing technique. Multi-variable regression analysis and surface plots were performed to illustrate the significant coefficients and contribution of the machining variables (i.e., feed, speed, and laminate thickness) on machinability parameters (i.e., the thrust force, torque, temperatures, and delamination). It is concluded that the cutting time, as a function of machining variables, has significant control over the induced temperature and, thus, the force, torque, and delamination factor in drilling GFRP composites. The maximum temperature recorded by the IR camera is lower than that of the instrumented drill because the IR camera cannot directly measure the tool-work interaction zone during the drilling process. At the same cutting condition, it is observed that by increasing the thickness of the specimen, the temperature increased. Increasing the thickness from 2.6 to 7.7 had a significant effect on the heat distribution of the HAZ. At a smaller thickness, increasing the cutting speed from 400 to 1600 rpm decreased the maximum thrust force by 15%. The push-out delaminations of the GFRP laminate were accompanied by edge chipping, spalling, and uncut fibers, which were higher than those of the peel-up delaminations.

Thermo-Mechanical and Delamination Properties in Drilling GFRP Composites by Various Drill Angles.

This manuscript aims to study the effects of drilling factors on the thermal-mechanical properties and delamination experimentally during the drilling of glass fiber reinforced polymer (GFRP). Drilling studies were carried out using a CNC machine under dry cutting conditions by 6 mm diameter with different point angles of ∅ = 100°, 118°, and 140°. The drill spindle speed (400, 800, 1600 rpm), feed (0.025, 0.05, 0.1, 0.2 mm/r), and sample thickness (2.6, 5.3, and 7.7 mm) are considered in the analysis. Heat affected zone (HAZ) generated by drilling was measured using a thermal infrared camera and two K-thermocouples installed in the internal coolant holes of the drill. Therefore, two setups were used; the first is with a rotating drill and fixed specimen holder, and the second is with a rotating holder and fixed drill bit. To measure thrust force/torque through drilling, the Kistler dynamometer model 9272 was utilized. Pull-in and push-out delamination were evaluated based on the image analyzed by an AutoCAD technique. The regression models and multivariable regression analysis were developed to find relations between the drilling factors and responses. The results illustrate the significant relations between drilling factors and drilling responses such as thrust force, delamination, and heat affect zone. It was observed that the thrust force is more inspired by feed; however, the speed effect is more trivial and marginal on the thrust force. All machining parameters have a significant effect on the measured temperature, and the largest contribution is of the laminate thickness (33.14%), followed by speed and feed (29.00% and 15.10%, respectively), ended by the lowest contribution of the drill point angle (11.85%).

The influence of MoO3-NPs on agro-morphological criteria, genomic stability of DNA, biochemical assay, and production of common dry bean (Phaseolus vulgaris L.).

Molybdenum is considered one of the most important micronutrients applied as a foliar fertilizer for common dry bean. In this study, molybdenum oxide nanoparticles (MoO3-NPs) were applied in different concentrations (0, 10, 20, 30 and 40 ppm) over two sequent seasons, 2018 and 2019, to investigate their effect on the plant morphological criteria, yield, and the genomic stability of DNA. The results showed that the application of 40 ppm MoO3-NPs as a foliar fertilizer showed preferable values of plant morphological criteria, such as the number of leaves and branches per plant, as well as the fresh and dry weight with regard to the common bean plant. In addition, the seed yield increased by 82.4% and 84.1% with 40 ppm, while the shoot residue increased by 32.2% and 32.1% with 20 ppm of MoO3-NPs during two seasons, 2018 and 2019, respectively. Furthermore, the common bean treated with 20 and 40 ppm MoO3-NPs had positive unique bands with ISSR primer 848 at 1400 bp (Rf 0.519) and with primer ISSR2M at 200 bp (Rf 0.729), respectively. In addition, SDS-PAGE reveald some proteins in seedlings which were absent in the flowering stage at 154, 102, 64, 37 and 34 KDa, which may be due to differences in plant proteins required for metabolic processes in each stage. In conclusion, the application of 40 ppm MoO3-NPs was more effective on the productivity of the common bean plants.

Template-free microwave-assisted hydrothermal synthesis of manganese zinc ferrite as a nanofertilizer for squash plant (Cucurbita pepo L).

Manganese, zinc, and iron are the most essential micronutrients required for plant growth and applied as foliar fertilizers. Herein, a simple template-free microwave-assisted hydrothermal green synthesis technique was adapted to produce manganese zinc ferrite nanoparticles (Mn0.5Zn0.5Fe2O4 NPs) at different temperatures (100, 120, 140, 160 and 180 °C). The prepared nanomaterials were employed at different concentrations (0, 10, 20, and 30 ppm) as foliar nanofertilizers during the squash (Cucurbita pepo L) planting process. X-ray diffraction patterns of the prepared nanomaterials confirmed successful production of the nanoferrite material. The prepared nanofertilizers showed type IV adsorption isotherm characteristic for mesoporous materials. FE-SEM and HR-TEM imaging showed that the nanoparticles were cubic shaped and increased in particle size with the increase in microwave temperature during production. The impact of application of the synthesized ferrite nanoparticles on vegetative growth, proximate analysis, minerals content and the yield of squash plant was investigated for two consecutive successful planting seasons. The nanoferrite synthesized at 160 °C and applied to the growing plants at a concentration of 10 ppm gave the highest increase in % yield (49.3 and 52.9%) compared to the untreated squash for the two consecutive seasons, whereas the maximum organic matter content (73.0 and 72.5%) and total energy (260 and 258.3 kcal/g) in squash leaves were obtained in plants treated with 30 ppm ferrite nanoparticles synthesized at 180 °C. On the other hand, the maximum organic matter content (76.6 and 76.3%) and total energy (253.6 and 250.3 kcal/g) in squash fruits were attained with plants supplied by 20 ppm ferrite nanoparticles synthesized at 160 °C. These results indicate that the simple template-free microwave-assisted hydrothermal green synthesis technique for the production of manganese zinc ferrite nanoparticles yields nanoparticles appropriate for use as fertilizer for Cucurbita pepo L.

Preparation and characterization of chitosan/polyacrylic acid/copper nanocomposites and their impact on onion production.

Chitosan nanoparticles (CS-NPs) and chitosan/polyacrylic acid hydrogel nanoparticles (CS/PAA-HNPs) were obtained by ionic gelation with tripolyphosphate anions and copolymerization of CS with acrylic acid (AA), respectively. The prepared NPs were loaded by different concentrations of copper (1, 2 and 3% with respect to CS) to obtain chitosan/copper nanocomposites (CS/Cu-NCs) and chitosan/polyacrylic acid/copper hydrogel nanocomposites (CS/PAA/Cu-HNCs). The prepared NPs and their NCs were characterized by different techniques. The swelling properties and copper release from CS/Cu-NCs and CS/PAA/Cu-HNCs were evaluated. The antibacterial activity of the prepared samples against bacteria (e.g., Staphylococcus aureus and Pseudomonas aeruginosa), fungi, and yeast were investigated. The results displayed that the copper release, as well as the swelling percentage of CS/PAA/Cu-HNCs, were higher than that of CS/Cu-NCs. Furthermore, the impact of using CuSO4, CS/Cu-NCs, and CS/PAA/Cu-HNCs as a different source of copper on chlorophyll content, vegetative growth, minerals content, and the yield of onion plants during two seasons 2016 and 2017 were studied. It was found that the yield, plant growth, and nutrient content of onion bulbs were improved using CS/PAA-HNPs, which was loaded with 75 ppm copper, as foliar spray for onion plants.