Asmussensahl4397

From the results, it was found that ΔD and ΔH were less when EDM was performed using novel electrodes.Adding fibers to concrete helps enhance its tensile strength and ductility. Synthetic fibres are preferable to steel ones which suffer from corrosion that reduces their functionality with time. More consideration is given to synthetic fibres as they can be sourced from waste plastics and their incorporation in concrete is considered a new recycling pathway. Thus, this work investigates the potential engineering benefits of a pioneering application using extruded macro polyfibres in concrete. Two different fiber dosages, 4 kg/m3 and 6 kg/m3, were used to investigate their influence based on several physical, mechanical and microstructural tests, including workability, compressive strength, modulus of elasticity, splitting-tensile strength, flexural test, CMOD, pull-out test and porosity. The test results revealed a slight decrease in the workability of the fibre-reinforced concrete, while all the mechanical and microstructural properties were enhanced significantly. It was observed that the compressive, splitting tensile and bonding strength of the concrete with 6 kg/m3 fibre dosage increased by 19.4%, 41.9% and 17.8% compared to the plain concrete specimens, respectively. Although there was no impact of the fibres on the modulus of rupture, they significantly increased the toughness, resulting in a progressive type of failure instead of the sudden and brittle type. Moreover, the macroporosity was reduced by the fibre addition, thus increasing the concrete compressive strength. Finally, simplified empirical formulas were developed to predict the mechanical properties of the concrete with fibre addition. read more The outcome of this study will help to increase the implementation of the recycled plastic waste in concrete mix design and promote a circular economy in the waste industry.The compound 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) is an eco-friendly water treatment agent possessing flame-retardant phosphorus element and multi-carboxylic acid groups in its molecular structure. In the present work, PBTCA is employed as a finishing agent to improve the flame retardancy of the wool fabrics by the pad-dry-cure technique. The treated wool (10.2% weight gain) by 100 g/L of PBTCA showed an increased flame retardancy with a limiting oxygen index value (LOI) of 44% with a minimum char length of 40 mm. Importantly, the treated wool can self-extinguish after 30 washing cycles. The PBTCA-treated wool exhibited better stability with obviously increased char residue of 39.7% and 28.7% at 600 °C, while only 25.9% and 13.2% were measured for the control wool in nitrogen and air atmosphere, respectively. In addition, the high thermal stability of the treated wool with astonishing char-forming ability is confirmed by the SEM images of the wool after the isothermal heating treatment at different temperatures. Finally, a two-stage flame-retarding mechanism of enhanced crosslinking and char formability of PBTCA-treated wool is proposed and analyzed by infrared spectroscopy (TG-FTIR) and thermal (DSC and TGA) results of the pyrolytic volatiles of the treated wool.The contamination of hydrosoluble pesticides in water could generate a serious problem for biotic and abiotic components. The removal of a hazardous agrochemical (paraquat) from water was achieved by adsorption processes using poly(vinyl alcohol)-cyclodextrin nanosponges, which were prepared with various formulations via the crosslinking between citric acid and β-cyclodextrin in the presence of poly(vinyl alcohol). The physicochemical properties of nanosponges were also characterized by different techniques, such as gravimetry, thermogravimetry, microscopy (SEM and Stereo), spectroscopy (UV-visible, NMR, ATR-FTIR, and Raman), acid-base titration, BET surface area analysis, X-ray diffraction, and ion exchange capacity. The C10D-P2 nanosponges displayed 60.2% yield, 3.14 mmol/g COOH groups, 0.335 mmol/g β-CD content, 96.4% swelling, 94.5% paraquat removal, 0.1766 m2 g-1 specific surface area, and 5.2 × 10-4 cm3 g-1 pore volume. The presence of particular peaks referring to specific functional groups on spectroscopic spectra confirmed the successful polycondensation on the reticulated nanosponges. The pseudo second-order model (with R2 = 0.9998) and Langmuir isotherm (with R2 = 0.9979) was suitable for kinetics and isotherm using 180 min of contact time and a pH of 6.5. The maximum adsorption capacity was calculated at 112.2 mg/g. Finally, the recyclability of these nanosponges was 90.3% of paraquat removal after five regeneration times.In recent years, polymer engineering, at the molecular level, has proven to be an effective strategy to modulate thermal conductivity. Polymers have great applicability in the food packaging industry, in which transparency, lightness, flexibility, and biodegradability are highly desirable characteristics. In this work, a possible manner to adjust the thermal conductivity in cassava starch biopolymer films is presented. Our approach is based on modifying the starch molecular structure through the addition of borax, which has been previously used as an intermolecular bond reinforcer. We found that the thermal conductivity increases linearly with borax content. This effect is related to the crosslinking effect that allows the principal biopolymer chains to be brought closer together, generating an improved interconnected network favoring heat transfer. The highest value of the thermal conductivity is reached at a volume fraction of 1.40% of borax added. Our analyses indicate that the heat transport improves as borax concentration increases, while for borax volume fractions above 1.40%, heat carriers scattering phenomena induce a decrement in thermal conductivity. Additionally, to obtain a deeper understanding of our results, structural, optical, and mechanical characterizations were also performed.In the context of the SARS-CoV2 pandemic and because of the surgical and FFP2 mask (equivalent to the American N95 masks) shortages, studies on efficient sterilization protocols were initiated. As sterilization using irradiation is commonly used in the medical field, this method was among those that were evaluated. In this work, we tested irradiation under vacuum and under air (under both γ-rays and e-beams), but also, for acceptance purposes, undertook washing prior to the e-beam irradiation sterilization process. This article deals with the modifications induced by the sterilization processes at the molecular and the macromolecular scales on an FFP2 mask. Fourier transform infrared spectroscopy in attenuated total reflectance mode, size-exclusion chromatography and thermal-desorption-gas chromatography-mass spectrometry were used to characterize possible damage to the materials. It appeared that the modifications induced by the different sterilization processes under vacuum were relatively tenuous and became more significant when irradiation was performed using γ-rays under air.The rigidity of structures made of polymer composite materials, operated at elevated temperatures, is mainly determined by the residual rigidity of the polymer binder (which is very sensitive to elevated temperatures); therefore, the study of ways to increase the rigidity of polymer materials under heating (including prolonged heating) is relevant. In the previous research, cured thermosetting polymer structure's non-stability, especially under heating, is determined by its supra-molecular structure domain's conglomerate character and the high entropy of such structures. The polymer elasticity modeling proved the significance of the entropy factor and layer (EPL) model application. The prolonged heating makes it possible to release adsorptive inter-layer bonds and volatile groups. As a result, the polymer structure is changing, and inner stress relaxation occurs due to this thermo-process, called thermo-relaxation. The present study suggests researching thermo-relaxation's influence on polymers' deformability under load and heating. The research results prove the significant polymer structure modification due to thermo-relaxation, with the polymer entropy parameter decreasing, the glassing onset temperature point (Tg) increasing by 1.3-1.7 times, and the modulus of elasticity under heating increasing by 1.5-2 times.Seawater treated with lime and sodium carbonate in different proportions to reduce magnesium and calcium contents is used in flocculation and sedimentation tests of artificial quartz and kaolin tailings. Solid complexes were separated from water by vacuum filtration, and factors such as lime/sodium carbonate ratio, kaolin content, flocculation time, and flocculant dose are evaluated. The growth of the aggregates was captured in situ by a focused beam reflectance measurement (FBRM) probe. Solid magnesium and calcium complexes are formed in raw seawater at pH 11, impairing the performance of flocculant polymers based on polyacrylamides. The results show that the settling rate improved when the treatment's lime/sodium carbonate ratio increased. That is, when a greater removal of magnesium is prioritized over calcium. The amount of magnesium required to be removed depends on the mineralogy of the system more clay will require more significant removal of magnesium. These results respond to the structural changes of the flocs, achieving that the more magnesium is removed, the greater the size and density of the aggregates. In contrast, calcium removal does not significantly influence flocculant performance. The study suggests the necessary conditions for each type of tailing to maximize water recovery, contributing to the effective closure of the water cycle in processes that use seawater with magnesium control.In this study, two types of single polymer films have been inserted in a composite laminate to examine their toughening effects on mechanical properties. The first is a thermoplastic polyurethane (PU) film, and the second is an adhesive epoxy film featuring a polyester net. The laminates were manufactured either using a co-curing (CC) process or a secondary bonding (SB) process used for the epoxy film. Mode I and mode II interlaminar fracture toughness were measured for laminates manufactured by both processes and compared with the corresponding reference laminate toughness. A significant increase in both mode I and mode II toughness resulted when introducing a single PU film, approximately 290% and 50%, respectively. Similarly, the epoxy film improved the interlaminar fracture properties; the CC process produced an increase of 175% for mode II toughness, while the SB adhesive film showed an increase of 75% for mode II toughness.Considering that the processes of PEEK discoloration caused by either intrinsic or extrinsic factors require elucidation, the aim of this study was to investigate the long-term effect of the combined action of ageing and immersing solutions on the optical properties and color stability of PEEK material, related to surface processing (polishing or glazing). (2) Methods This study aims to determine the influence of different ageing and staining protocols on optical properties, color changes, and surface roughness of a reinforced PEEK material (bioHPP, Bredent, Senden, Germany). For ageing, specimens were submitted to 5000 cycles in a 55 °C bath and a 5 °C bath filled with distilled water. For staining, thermal cycling was performed in a hot coffee bath (55 °C) and a bath filled with distilled water (37 °C) and in a cold juice bath (5 °C) and a bath filled with distilled water (37 °C). Translucency (TP) and opalescence (OP) parameters were determined, the total color change value (ΔΕ*) was calculated, specimens' surface roughness was analyzed, and statistical analyses were performed.