Improvement Of Mechanical Properties Research Articles

Effect of Sc on the recrystallization behavior and mechanical properties of Al-Zn-Mg-Cu-Zr alloys under isothermal multidirectional compression

To better achieve grain refinement and further optimize the comprehensive mechanical properties of Al-Zn-Mg-Cu-Zr alloys, this paper investigates the effect of trace Sc on the recrystallization behavior of Al-Zn-Mg-Cu-Zr alloys under isothermal multidirectional compression (IMC) and the mechanical properties in two-stage aging state. It was discovered that the addition of Sc enhanced the tensile and yield strengths of the alloys by 3.8% and 4.3%, respectively, and simultaneously increased the elongation from 13.4% to 15.4%. The OM, EBSD and TEM techniques were used to characterize the microstructure of the alloy. The results showed that the Al3(Sc,Zr) phase produced by the addition of 0.25% Sc not only refines the grains, but also changes the recrystallization behavior of the alloy by pinning the dislocations and (sub) grain boundaries in the combination of IMC deformation. It inhibits the generation of geometric dynamic recrystallization (GDRX) grains and the nucleation of discontinuous dynamic recrystallization (DDRX) grains but promotes the formation of continuous dynamic recrystallization (CDRX) as the predominant mode of dynamic recrystallization. The alloy gains a finer grain structure by simultaneously promoting the formation and inhibiting the growth of recrystallized grains. As a result, the improvement in the overall mechanical properties of Al-Zn-Mg-Cu-Sc-Zr alloys brought about by the addition of Sc can be attributed primarily to the refinement of the initial as-cast grains, as well as fine-grain strengthening due to the inhibition of recrystallized grain growth and the Orovan strengthening of the nanoscale secondary phase Al3(Sc,Zr) itself.

Improvement of microstructure and mechanical properties of laser welded Al-Si coated 22MnB5 steel joints by austenitic element copper

In this experiment, the effects of different copper foil thicknesses on the morphology, structure, and mechanical properties of laser lap welded 22MnB5 steel joints were studied. The aim was to reduce the damage of Al-Si coating and increase the mechanical properties of welded joints. As the thickness of copper foil increases from 0 to 100μm, there was a gradual decrease in the presence of δ-ferrite in the fusion zone (FZ) and fusion boundary (FB), while the copper-rich content of lath martensite (LM) gradually increased. The reason was that Cu is an austenite element which can expand the γ phase area and play a stabilizing and strengthening role. The result of JmatPro software can support it. It found peritectic reaction (L+δ→γ) range expanded from 1414 to 1422°C to 1436–1453°C which led to more γ phases formed during the solid-state phase transition (δ→γ) at high temperature. Based on this phenomenon, as the copper foil increased (0–100μm), the joint tensile strength increased from 361 MPa to 706 MPa. However, after adding too much copper foil (200μm), the microstructure of FZ varied to a copper-rich phase (ε-Cu) with low hardness and brittleness which adhered to the martensite grain boundaries and reduced the bonding force of the crystal boundaries, so the the mechanical properties of the weld joint seriously reduced (232 MPa). When the copper foil was thin or non-existent (0–30μm), there was still more delta ferrite in FB (low strength and brittle), and the fracture type of the joint mainly appeared as a cleavage fracture. When adding 100μm copper foil, the fracture expressed ductile fracture due to the interfacial fracture due to the lack of δ-ferrite in FB. If the thickness of Cu increased to 200μm, the fracture changed back to FB which expressed a quasi-cleavage fracture.

Lipoic acid/trometamol assembled hydrogel as injectable bandage for hypoxic wound healing at high altitude

To avoid chronic wound formation caused by hypoxia and cold in high-altitude areas, developing an injectable, strongly adhesive hydrogel bandage with controllable oxygen generation and inflammation regulation functions is of great value. Poly(lipoic acid) (PLA)-based adhesives have been well-developed from polymerization of α-Lipoic acid (LA), showing attractive performances including simple preparation, strong adhesion, anti-inflammatory. However, injection of PLA-based adhesives has not been well-practiced because of its high viscosity and strong adhesion. Herein, LA and trometamol are firstly found to rapidly gel into a supramolecular hydrogel within 5 min at room temperature, exhibiting well-performed injectability. Further presence of Ce3+ significantly accelerates this gelation within 2 min. Meanwhile, dopamine (DA) and g-C3N4 nanosheet synergistically endow the injectable hydrogel with photothermal function, which can convert near-infrared-light (NIR) into heat, triggering LA polymerization and achieving post-injection enhancement. In terms of bandage performance after molding, the introduction of Ce3+, DA, and g-C3N4 contributes to the improvement of mechanical and adhesion properties. The injectable hydrogel bandage not only possesses highly tough and adhesive features, but also produces oxygen under NIR irradiation, effectively alleviating wound hypoxia, creating anti-inflammatory microenvironment, and significantly promoting healing of incision in a low-pressure oxygen environment.

Effect of graphene reinforcement on the tensile and flexural properties of thermoplastic polyurethane nanocomposite using experimental and simulation approach

ABSTRACT This study investigates the integration of graphene (Gr) nanoparticles into polyurethane (PU) matrices to enhance mechanical properties, focusing on Young’s modulus, tensile strength, and flexural strength. Utilising a Representative Volume Element (RVE) analysis with 1 × 1 × 1 μm dimensions, the research evaluates PU/Gr composites at varying volume fractions. Results indicate substantial improvements in mechanical properties, with the 0.05 PU/Gr composite exhibiting the highest enhancements, including a 25% increase in Young’s modulus and 26% and 31% enhancements in tensile and flexural strengths, respectively, compared to pure PU. Fractography confirms the transition from ductile to brittle behaviour with Gr incorporation. The RVE method accurately predicts Young’s modulus, aligning closely with experimental and micromechanical model data. Additionally, ANSYS simulation tests show results within a 10% error margin. The findings suggest significant potential for the development of high-performance composite materials applicable across industries like aerospace, automotive, and construction.

Особливості електронно-променевого зварювання магістральних трубопроводів з титанового сплаву

Titanium alloys have high strength and satisfactory weldability. They are widely used in the production of aircrafts and other structural elements in the modern aerospace industry. However, due to a high requirement for aviation and rocket-space technology, increasing the reliability and durability of responsible purpose remains an urgent issue. In this study, the results of welding tubular billets with an electron beam are presented. The subject of this article is the features of tubular billets made of complex titanium alloy electron beam welding. The purpose of this work is to ensure that welds of tubular work pieces have a high level of mechanical properties, based on the welding modes experimental testing results. To achieve this goal, the following tasks were set up and solved in this work: to investigate the mechanism of pore formation in welded joints; to study the effect of electron beam welding on the properties of the weld; ensure high indicators of physical and welded joints mechanical properties. The following research results were obtained. It was possible to obtain satisfactory characteristics of the welded joint by welding in the lower position on the substrate and in the horizontal position. The use of heat treatment increases the strength of welded joints to the level of the base metal. Welded seams, regardless of the welding method, have a coarse-grained structure with liquefaction heterogeneity, which is manifested in uneven etching of the seam. Conclusions: Various metallurgical aspects of titanium electron beam welding were studied. During electron beam welding of tubular blanks, pores are formed mainly near the fusion zone and in the seam axis. Edge mechanical processing, speed reduction, work piece rotation, and welded metal remelting dramatically reduce the number of pores in seams welded in the lower position. Crater removal with a stationary work piece avoids root defect formation in the area of annular seam closure. The obtained results have scientific and practical value in the welded joints of tubular blanks mechanical properties improvement.

Enhancing load-bearing capacity of martensitic stainless steel resistance spot welds: Microstructural vs. geometrical approaches

The load-bearing capacity of resistance spot welds is determined by a combination of weld geometrical attributes, such as the size of the weld nugget (WN), and weld metallurgical features. When resistance spot welds are made on martensitic stainless steels (MSSs), their load-bearing capacity is reduced due to the formation of a brittle martensitic microstructure within the WN. In this study, we investigated two distinct approaches to enhance the mechanical properties of AISI420 MSS spot welds. The results indicated that manipulating the WN size did not effectively produce strong welds in both tensile-shear (TS) and cross-tension (CT) tests. Therefore, we focused on examining the impact of the weld microstructure by employing two different interlayers: low carbon steel (LCS) and pure nickel. The analysis using electron backscatter diffraction (EBSD) and electron probe microanalysis (EPMA), along with equilibrium and non-equilibrium phase diagrams, revealed that the microstructure of the WN with low carbon steel interlayer of various thicknesses exhibited similarities with spot welds made without an interlayer, and the solidification mode was still δ-ferrite. This microstructure primarily consisted of martensite (M) and likely residual delta ferrite (δ) phases, resulting in no significant improvements in mechanical properties. In contrast, the utilization of the nickel interlayer led to remarkable enhancements in mechanical properties. This improvement can be attributed to a shift in the solidification mode from primary delta (δ) to austenite (γ) within an optimal interlayer thickness. This transition facilitated the development of a predominantly austenitic (γ) microstructure, contributing to the formation of an exceptionally tough microstructure within the weld nugget. Consequently, the load-bearing capacity was significantly improved.

Experimental evaluation of bamboo natural fiber composite reinforced with SiO2 nanoparticles for aircraft applications

Purpose Composite materials have revolutionized the aerospace industry by offering superior structural qualities over traditional elements. This study aims to focus on the development and testing of bamboo natural fiber-based composites enhanced with SiO2 nanoparticles. Design/methodology/approach The investigation involved fabricating specimens with varying nanoparticle compositions (0, 10 and 20%) and conducting tensile, flexural, impact and fracture toughness tests. Results indicated significant improvements in mechanical properties with the addition of nanoparticles, particularly at a 10% composition level. Findings This study underscores the potential of natural fiber composites, highlighting their environmental friendliness, cost-effectiveness and improved structural properties when reinforced with nanoparticles. The findings suggest an optimal ratio for nanoparticle integration, emphasizing the critical role of precise mixing proportions in achieving superior composite performance. Originality/value The tensile strength, flexural strength, impact resistance and fracture toughness exhibited notable enhancements compared with the 0 and 20% nanoparticle compositions. The 10% composition showed the most promising outcomes, showcasing increased strength across all parameters.

Improvement in 3D printability, rheological and mechanical properties of pea protein gels prepared by plasma activated microbubble water

Three-dimensional (3D) food printing is one of the emerging processing technologies that enables the construction of complex food structures and customization. Although various food ingredients have been explored for their 3D printability, pea protein is among the plant proteins that have not been studied extensively on its 3D printability, owing to its native inability to hold shape and structure following extrusion. This study investigated the effect of plasma activated microbubble (PAMB) treatment on the thermal gelation and 3D printability of pea protein isolate (PPI). PAMB treatments with different combinations of discharge gases (80% argon and 20% air, 90% argon and 10% air, 100% argon, and 100% air) were applied to prepare PPI suspensions. These suspensions were then heated at 85 °C for 30 and 60 min, followed by immediate cooling to prepare PPI gels. The viscoelastic measurements and mechanical properties of PPI gels indicated that this combined application was suitable for 3D printing, with a notable increase in storage modulus (G '), loss modulus (G '') and compressive stress in PPI-PAMB gels. The 3D printed PPI gels prepared using PAMB treatment exhibited better structure retention, resistance to deformation, and stability during storage. The treatment using PAMB prepared by the combination of argon and air, i.e., 80% argon and 20% air and 90% argon and 10% air, resulted in PPI gels with better rheological properties, mechanical stability, and 3D printability. Freeze drying was investigated as a possible post-3D printing processing operation to enhance the shelf life and storage stability of 3D printed PPI gels. The moisture content, water activity, and textural properties of the freeze-dried 3D printed PPI were investigated.

Comparative Analysis of Crosslinking Methods and Their Impact on the Physicochemical Properties of SA/PVA Hydrogels.

Hydrogels, versatile materials used in various applications such as medicine, possess properties crucial for their specific applications, significantly influenced by their preparation methods. This study synthesized 18 different types of hydrogels using sodium alginate (SA) and two molecular weights of polyvinyl alcohol (PVA). Crosslinking agents such as aqueous solutions of calcium (Ca2+) and copper (Cu2+) ions and solutions of these ions in boric acid were utilized. The hydrogels were subjected to compression strength tests and drying kinetics analysis. Additionally, six hydrogel variants containing larger PVA particles underwent Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) post-drying. Some samples were lyophilized, and their surface morphology was examined using scanning electron microscopy (SEM). The results indicate that the choice of crosslinking method significantly impacts the physicochemical properties of the hydrogels. Crosslinking in solutions with higher concentrations of crosslinking ions enhanced mechanical properties and thermal stability. Conversely, using copper ions instead of calcium resulted in slower drying kinetics and reduced thermal stability. Notably, employing boric acid as a crosslinking agent for hydrogels containing heavier PVA molecules led to considerable improvements in mechanical properties and thermal stability.

Collagen-polyurethane-dextran hydrogels enhance wound healing by inhibiting inflammation and promoting collagen fibrillogenesis.

Diabetic foot ulcers are a serious complication of uncontrolled diabetes, emphasizing the need to develop wound healing strategies that are not only effective but also biocompatible, biodegradable, and safe. We aimed to create biomatrices composed of semi-interpenetrated polymer networks of collagen, polyurethane, and dextran, to enhance the wound healing process. The hydrogels were extensively characterized by various analytical techniques, including analysis of their structure, crystallinity, thermal properties, gelation process, reticulation, degradation, cell proliferation, and healing properties, among others. Semi-interpenetrated hydrogels containing dextran at levels of 10%, 20%, and 30% exhibited porous interconnections between collagen fibers and entrapped dextran granules, with a remarkable crosslinking index of up to 94% promoted by hydrogen bonds. These hydrogels showed significant improvements in mechanical properties, swelling, and resistance to proteolytic and hydrolytic degradation. After 24 h, there was a significant increase in the viability of several cell types, including RAW 264.7 cells, human peripheral blood mononuclear cells, and dermal fibroblasts. In addition, these hydrogels demonstrated an increased release of interleukin-10 and transforming growth factor-beta1 while inhibiting the release of monocyte chemotactic protein-1 and tumor necrosis factor-alpha after 72 h. Furthermore, these hydrogels accelerated the wound healing process in diabetic rats after topical application. Notably, the biomaterial with 20% dextran (D20) facilitated wound closure in only 21 days. These results highlight the potential of the D20 hydrogel, which exhibits physicochemical and biological properties that enhance wound healing by inhibiting inflammation and fibrillogenesis while remaining safe for application to the skin.

Ultra-Large Stress and Strain Polymer Nanocomposite Actuators Incorporating a Mutually-Interpenetrated, Collective-Deformation Carbon Nanotube Network.

Stimulus-responsive polymer-based actuators are extensively studied, with the challenging goal of achieving comprehensive performance metrics that include large output stress and strain, fast response, and versatile actuation modes. The design and fabrication of nanocomposites offer a promising route to integrate the advantages of both polymers and nanoscale fillers, thus ensuring superior performance. Here, it is started from a three-dimensional (3D) porous sponge to fabricate a mutually interpenetrated nanocomposite, in which the embedded carbon nanotube (CNT) network undergoes collective deformation with the shape memory polymer (SMP) matrix during large-degree stretching and releasing, increases junction density with polymer chains and enhances molecular orientation. These features result in substantial improvement of the overall mechanical properties and during thermally actuated contraction, the bulk SMP/CNT composites exhibit output stresses up to 19.5 ± 0.97MPa and strains up to 69%, accompanied by a rapid response and high energy density, exceeding the majority of recent reports. Furthermore, electrical actuation is also demonstrated via uniform Joule heating across the self-percolated CNT network. Applications such as low-temperature thermal actuated vascular stent and wound dressing are explored. These findings lay out a universal blueprint for developing robust and highly deformable SMP/CNT nanocomposite actuators with broad potential applications.

Influence of selected contaminations and melt filtration on the properties of ABS and ABS recyclate

AbstractPlastic recyclates can be contaminated with a variety of impurities due to their previous life, which cannot always be perfectly separated in recycling pretreatment steps. Hence melt filtration is an important step in reprocessing plastic recyclates to achieve material of sufficient purity, but it also leads to more stress on the material due to higher pressures and longer processing times. In our study, we investigated the influence of typical particulate impurities as may occur in recyclate on the mechanical and rheological properties of ABS. Even low amounts of contaminations lowered the key properties. Melt filtration of post‐consumer ABS recyclate with different mesh size melt screens showed little improvement of mechanical properties, but longer idle times and loss of material. Damage to the material caused by finer filtration could be shown by thermal measurements.Highlights Determination of properties of ABS contaminated with 0.5–2.0 wt.% of selected impurities (wood and rubber particles). Melt filtration of post‐consumer ABS recyclate with different melt screens. Investigation of process and properties of filtered ABS recyclate.

Strengthening and self‐healing of natural fiber composites via PLA core–shell nanofibers as healing agent carrier

AbstractThe resin‐rich region between the fiber laminates of a fiber‐reinforced composite is susceptible to matrix damage impeding the composite's integrity. Hence, this study intends to interlayer core–shell poly(lactic) acid (PLA) nanofibers between the flax fibers as a preventive and reactive mechanism to matrix damages in the resin‐rich area. The nanofibers prevent premature damage by suppressing or mitigating crack propagation and in the event of damage to the nanofibers, it reacts by releasing the encapsulated healing agent. Upon interlayering the flax fiber laminates with self‐healing core–shell nanofibers, the flexural modulus exhibited an increment of 31% whereas the short beam strength improved by 19%. Self‐healing traits of the composites were assessed by subjecting the composites to repeated flexural or short beam strength tests for several load cycles. Upon initial damage to the composites, the composites exhibited a full retention and improvement in mechanical properties. The self‐healing composites were also able to withstand more loading cycles than the conventional composite under repeated short‐beam strength tests. Under both configurations, the damaged self‐healing composites exhibited a residual strength greater than or equivalent to the ultimate strength of a pristine flax fiber composite.Highlights Fabrication of EP/flax self‐healing composites by PLA core–shell nanofibers. Interlayering healing nanofiber mats between flax fabrics in an FRP composite. Nanofiber interlayers exhibited a profound impact on the composite properties. Nano mats facilitate autonomous repair of internal defects within matrices. The self‐healing composites showed full retention and mechanical strength.

Investigation of the Effectiveness of Silicon Nitride as a Reinforcement Agent for Polyethylene Terephthalate Glycol in Material Extrusion 3D Printing.

Polyethylene terephthalate glycol (PETG) and silicon nitride (Si3N4) were combined to create five composite materials with Si3N4 loadings ranging from 2.0 wt.% to 10.0 wt.%. The goal was to improve the mechanical properties of PETG in material extrusion (MEX) additive manufacturing (AM) and assess the effectiveness of Si3N4 as a reinforcing agent for this particular polymer. The process began with the production of filaments, which were subsequently fed into a 3D printer to create various specimens. The specimens were manufactured according to international standards to ensure their suitability for various tests. The thermal, rheological, mechanical, electrical, and morphological properties of the prepared samples were evaluated. The mechanical performance investigations performed included tensile, flexural, Charpy impact, and microhardness tests. Scanning electron microscopy and energy-dispersive X-ray spectroscopy mapping were performed to investigate the structures and morphologies of the samples, respectively. Among all the composites tested, the PETG/6.0 wt.% Si3N4 showed the greatest improvement in mechanical properties (with a 24.5% increase in tensile strength compared to unfilled PETG polymer), indicating its potential for use in MEX 3D printing when enhanced mechanical performance is required from the PETG polymer.

Parts repairing and microstructural refinement of high-pressure die cast aluminum alloys through friction stir processing for bulk production

A key challenge in the production of high-grade automotive aluminum components through the High-Pressure Die Casting (HPDC) process is the imperative to minimize imperfection. In addressing this concern, this study utilizes friction stir processing (FSP), a widely recognized intense plastic deformation technique. FSP is applied to systematically alter the microstructure of HPDC Al-4Mg-2Fe, a prominent alloy extensively used in the die-casting sector. By using the pass strategy to incorporate both one-pass and two-pass approaches, the microstructure is selectively altered to establish a defect-free processed zone. The utilization of FSP demonstrates its efficacy in breaking aluminum dendrites and acicular silicon particles, leading to a uniformly dispersed arrangement of equiaxed silicon particles within the aluminum-based matrix. In addition, FSP eradicates porosity and disintegrates needle-like Fe particles, resulting in a more refined and homogeneously distributed structure. Subsequently, the material's mechanical properties processed by FSP were assessed in the longitudinal direction concerning the processing axis and then compared with those of the original base material.The microstructural refinement and reduction in porosity induced by FSP result in a notable enhancement in hardness, with an increase of 23 % after one pass and 37 % after two passes. The substantial improvement in mechanical properties during the FSP process is predominantly attributed to modifications in the morphology, refinement, and dispersion of intermetallic particles within the matrix. This improvement is further complemented by the ultrafine dispersion of casting defects.This study underscores the efficacy of FSP as a valuable tool for modifying microstructures and improving mechanical properties in HPDC Al-4Mg-2Fe alloys. Such advancements align with the lightweighting objectives pursued by the automotive industry.

Protective action of water-soluble fullerene adducts on the example of an adduct with l-arginine

We present radioprotective, antiglycating, and photoprotective properties of a water-soluble C60 fullerene derivative with l-arginine (C60-Arg) and composite films based on collagen containing C60-Arg. The synthesis of these materials is described. The identification of the synthesised materials was carried out using modern physicochemical methods of analysis. The physicochemical properties of aqueous solutions of C60-Arg, such as, particle size distribution, zeta potentials, distribution coefficient in the octan-1-ol–water system were measured. The computer simulation of the process of C60-Arg association in aqueous and isotonic solutions was carried out using Molecular Dynamics. Composite films based on collagen containing C60-Arg demonstrate significant improvement in mechanical properties, cell adhesion, and cell proliferation when the nano-modifier is added. This shows high potential for the use of the C60-Arg adduct in biomedicine.

Bismuth oxyiodide nanorods towards improvements in fire safety and mechanical properties of natural rubber

Fire safety represents an enduring challenge in the realm of polymer-based nanocomposites, significantly limiting their application. The utilization of bismuth oxyiodide in flame retardant applications offers advantages such as increased surface area for improved interaction with combustible materials, the formation of a uniform flame retardant layer at the interface, and enhanced thermal stability. Hence, this work explored a facile strategy to synthesize bismuth oxyiodide nanorods by hydrothermal method combined with ball milling in anticipation of constructing an efficient flame retardant system. The bismuth oxyiodide nanorods dispersed relatively uniformly in the natural rubber matrix and endowed natural rubber nanocomposites with enhanced mechanical properties and fire-safety. The resultant natural rubber nanocomposite containing 5 wt% of bismuth oxyiodide showed a 36 % improvement in the tensile strength and a 39 % increase in the tear strength compared to those of the neat natural rubber. Cone calorimeter tests revealed that the introduction of 5 wt% bismuth oxyiodide to natural rubber matrix remarkably reduced the peak of heat release rate and peak smoke production release by 22 % and 25 %, respectively. A rational flame retardant mode of action for bismuth oxyiodide nanorods was proposed based on the analysis of pyrolysis fragments and char residues. Hence, this work provides a green and feasible method to prepare bismuth oxyiodide nanorods for flame retardant natural rubber products.

Investigation of fracture behavior and mechanical properties of epoxy composites supported with MWCNTs microscopically

Adding of a multi-walled carbon nanotubes (MWCNTs) to epoxy resin has shown promising results in improving fracture toughness in bulk epoxy and carbon fiber-reinforced epoxy composites (CFRP). using a hand layup proceeding followed by the so called vacuum bagging process method, carbon fiber-reinforced polymer multi-wall carbon nanotubes (MWCNTs) was added to an epoxy resin with a weight percentage mixing of 1% wt., 1.25% wt., and 1.5 % wt. MWCNTs. Furthermore, the specimen underwent analysis via Fourier-Transform Infrared (FTIR) spectroscopy, and X-ray Diffraction (XRD) spectroscopy, the composites were subjected to a microscopic examination using a Scanning Electron Microscope (SEM). FTIR and XRD verified the folding and unfolding of the polymer, in addition, the mechanical properties including tensile strength, bending stress, and impact behavior were investigated as well as the hardness test. The obtained results showed a significant improvement of about (40 %) in tensile strength, (53 %) in bending stress at 1 % wt. MWCNTs, and (70 %) percentage increment in the strength of Impact at 1.25 % wt. MWCNTs. And the gained hardness was about 40.5 HV which were compared with a reference substance named Carbon Fiber (CF) without any addition of nano materials. Carbon nanotubes have demonstrated their potential to enhance the mechanical properties of fiber-reinforced polymers, so this investigative study employs comprehensive characterization techniques, and demonstrates significant improvements in mechanical properties for the modified polymeric composite materials supported with nano materials.

Melt processing of graphene-coated polylactide granules for producing biodegradable nanocomposite with higher mechanical strength

ABSTRACT Innovative melt processing technology is necessary for the production of biodegradable polylactide/graphene nanocomposites. In this paper, we present the aqueous spray coating method to prepare graphene-coated polylactide granules for improving the distribution of small graphene contents in polymer matrix during the melt mixing process. Three types of functionalized graphene nanosheets, including graphene oxide (GO), reduced graphene oxide (RGO) and poly(ethylene glycol)/RGO (PEG/RGO), were investigated in the formations of graphene coatings on polylactide granules and subsequent melt-processed nanocomposites. It is found that RGO nanosheets have good interfacial compatibility to form better coatings on polylactide granules. Melt processing of graphene-coated granules produced polylactide/graphene nanocomposites with higher mechanical strengths. Nanocomposite materials containing 0.1% RGO showed the best improvements of mechanical and thermal properties. As-prepared nanomaterials and nanocomposites were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-Vis), attenuated total reflectance infrared spectroscopy (ATR-FTIR), tensile, flexural and impact measurements, differential scanning calorimetry (DSC) and integrated thermogravimetric analysis (TGA-DTA). In general, the innovative strategy of aqueous spray coating and melt processing is applicable for manufacturing biodegradable PLA/graphene nanocomposites in the sustainable trend of environmentally friendly development.

EFFICIENT WASTEWATER TREATMENT THROUGH INTEGRATED WATER HYACINTH SYSTEMS: ADVANCES AND APPLICATIONS IN CONCRETE

This research focuses on enhancing water quality for concrete construction by utilizing treated wastewater from wetlands. The study employs a dual-stage treatment process involving charcoal and aggregate layers for primary treatment, followed by water hyacinths for secondary treatment. Investigating water hyacinths’ ability to absorb nutrients and contaminants from wastewater is a unique aspect of the study, offering a potential solution for soil and water remediation. Water hyacinths, especially stems and leaves, act as natural filters, effectively indicating heavy-metal pollution in tropical regions. The primary goal is heavy-metal removal from wastewater, allowing treated-water use in concrete production at varying proportions (20 %, 40 %, 60 %, 80 %, and 100 %). Silica fume at 15 % concentration is incorporated to enhance the concrete’s durability. Concrete specimens undergo thorough preparation and mechanical property evaluations, compared to conventional M20-grade concrete. The results reveal improvements in mechanical properties, particularly with 80 % treated wastewater in the mix. The dual-stage treatment process removes heavy metals, and the inclusion of silica fume enhances the concrete’s durability and resistance.