MPa Tensile Strength Research Articles

HEMP FIBER REINFORCED SUSTAINABLE “GREEN” COMPOSITE PRODUCTION WITH EPOXIDIZED SOYBEAN OIL

Due to the rising environmental concerns, industry branches are pushed to research and invest sustainable materials and technologies. In this context, this study aimed to combine a sustainable fiber and matrix material to produce green composite. For this purpose, epoxidized soybean oil and hemp fiber were utilized for composite production. Sebacic acid and maleic anhydride were used as hardeners. Histidine and glycerol were applied as accelerator and starter, respectively. Mechanical performance of the composites was evaluated by tensile and impact tests. Hemp fiber reinforcement resulted in improvement on tensile properties, up to 2.6 MPa tensile strength and 11.7 kJ/m2 impact strength. Thermal properties were determined by TGA and DSC analyses. The changes in molecular level after curing was traced with FTIR measurements and surface morphology was monitored with SEM imaging.

Mechanical response and microstructural evolution of a composite joint fabricated by green laser dissimilar welding of VCoNi medium entropy alloy and 17-4PH stainless steel

In engineering structures, the application of advanced alloys, such as the VCoNi medium-entropy alloy (VCoNi-MEA), with remarkable tensile strength (> 1 GPa) and superior ductility necessitates the employment of dissimilar joints. This study pioneers the dissimilar joining of VCoNi-MEA and 17–4 precipitation hardening stainless steel (17–4PH STS) using state-of-the-art green laser beam welding (LBW). To evaluate and optimize the experimental parameters, two welding speeds (200 and 300 mm/s) along with post-weld heat treatment (PWHT) were incorporated. High-quality welded joints with a single-phase face-centered cubic (FCC) structure in the fusion zone (FZ), minimal precipitates (< 1.6 %), and no visible cracks were successfully created. The LBW process demonstrated effective low-heat input characteristics, evident from a considerably narrow heat-affected zone (HAZ). Control over FZ width and grain size was achieved, measuring 600 and 112 μm at low welding speed and 250 and 49 μm at high welding speed, respectively, significantly lower than previous studies. A remarkably high yield strength (YS) of ∼620 MPa and ultimate tensile strength (UTS) up to 845 MPa were observed in the as-welded conditions, improving to ∼645 and 875 MPa, respectively, after PWHT. This enhancement in mechanical properties is primarily attributed to lattice friction induced by V addition. PWHT also improved joint ductility, increasing from 3.5 % to 8.6 % (low-speed) and from 6.3 % to 9.2 % (high-speed). The reduction in crystallographic orientation achieved using a higher welding speed and PWHT emerged as a major reason for improved mechanical properties. Slip-based deformation mechanisms dominated across all conditions, featuring crystallographically aligned slip bands. Interactions between existing and additional slip bands formed a dense dislocation network crucial for enhanced elongation after PWHT. Thermodynamic parameters elucidating phase stability in the observed FZs and contributions to superior YS were calculated and comprehensively discussed.

Sustainable Jute Fiber Sandwich Composites with Hybridization of Short Fiber and Woven Fabric Structures in Core and Skin Layers

AbstractSustainable hybrid composites, made of two different natural plant fiber types, are increasingly being attracted by composite researchers, for their cost effectiveness and ability to control mechanical performances through varying weight ratios of different fibers. In contrast, their lower mechanical properties are reported in the literature, because of strength variations of different fiber types and an improper fiber‐matrix stress distribution. Therefore, it is aimed to develop sustainable hybrid composites from two dry fiber preforms—woven fabric and short fiber preform—originated from same fiber type (jute). A highly packed short fiber preform is used as the core layer, while woven fabrics (plain/twill–rib/twill–diamond) are used in the skin layers for producing sandwiched hybrid jute composites. Mechanical tests and scanning electron microscopy images show that hybridized plain fabric/short fiber preform composites have better mechanical properties (≈58 MPa tensile strength/≈117 MPa flexural strength/≈112.12 kJm−2 impact strength with an ≈487.4% improvement) compared to other fabric structures hybrid/nonhybrid composites. This enhancement is related to the interlocking of short fibers with long plain fabric leading to a strong fiber‐matrix interfacial bonding. Thus, this developed hybrid composites, can be applied in many semi‐structural applications, wherein composites’ low cost and mechanical performances are primary concerns.

Ti-Mo microalloyed medium Mn steels: Precipitation and strengthening mechanism

Medium-Mn steels possess an exceptional strength-ductility balance but normally relatively low yield strength, which hinders their practical applications especially in ultra-high strength structural components. In this study, the simultaneous addition of Ti and Mo was proposed to improve the yield strength of medium-Mn steels, together with the systematic experimental and theoretical investigations on the precipitation behavior of (Ti, Mo)C carbides and its effects on the microstructure-properties relationship. The addition of Ti and Mo increases yield strength by 150∼350 MPa and ultimate tensile strength by 55∼320 MPa without a significant loss of ductility. Based on the intercritically annealed microstructure close to equilibrium as well as the nucleation and growth kinetic theory, the Ti–Mo addition can reduce the fraction of austenite, but increase the mechanical stability of austenite by refining the mean grain size of austenite. Mo was found to increase the precipitate density of (TixMo1-x)C by lowering the interfacial energy between the nano-precipitates and the matrix, and reduce the mean size of precipitates. A maximum increment in yield strength (∼350 MPa) was achieved at 610 °C, which was mainly attributed to the combined effects of grain refinement and precipitation hardening due to the addition of Ti and Mo.

CeO2-loaded PVA/GelMA core-shell nanofiber membrane to promote wound healing

Chronic wounds are a significant health issue due to various pathogenic abnormalities that hinder the healing process. Nanofiber membranes, with their favorable conductivity for cell growth, proliferation, and adhesion, offer immense potential for effective chronic wound healing. In this study, we utilized the coaxial electrospinning method to synthesize core-shell structured nanofiber membranes for chronic wound healing. To obtain superior nanofiber membranes, we modified the shell part of the electrospun nanofiber by combining gelatin methacrylate (GelMA) with cerium oxide (CeO2). The results show that these nanofibers exhibit promising wound healing properties, including ideal hydrophilicity, swelling ratio, porosity, mechanical properties, antibacterial activity, and fibroblast cell viability. With the addition of 3 % w/v CeO2 nanoparticles (PGCe-3 CL sample), the nanofiber membrane had a 53.7° water contact angle, 384.47 % swelling ratio, 83.91 % porosity, and 8.49 MPa tensile strength, which are optimal for the wound healing process. The PGCe-3 CL sample also demonstrated increased antibacterial activity, reducing bacterial colonies by up to 88.46 % for S. aureus and 93.14 % for E. coli compared to PG-CL and PGCe-1.5 CL. Furthermore, the cell viability test showed that the nanofiber membranes are non-toxic to human dermal fibroblast cells and significantly enhance cell proliferation compared to other samples. Accordingly, the synthesized nanofiber membranes loaded with nano CeO2 in this study show promising performance as suitable dressings for chronic wounds. Moreover, the findings of this study provide valuable insights for developing more effective and innovative materials for chronic wound healing.

Fabrication of chitosan/guar gum/polyvinyl alcohol films incorporated with polymethoxyflavone-rich citrus extracts: Postharvest shelf-life extension of strawberry fruits

In this study, chitosan/guar gum/polyvinyl alcohol (CGP) matrix (CGPC) films with different concentrations of polymethoxyflavone (PMF)-rich citrus extracts were developed. The results showed that these films had 11.90–16.77 μm of thickness, 32.53 %–41.53 % of moisture content, 33.16 %–121.64 % of water solubility, 2.14–3.18 × 10−10 g m−1 s−1 Pa−1 of water vapor permeability, 65.57 %–148.74 % degree of swelling, 6.08–16.05 MPa of tensile strength and 28.25 %–62.82 % of elongation at break. SEM and TEM observations indicated that the content of PMF-rich extracts affected the distribution and structure of the film matrix, which were confirmed by FT-IR and XPS outcomes. TGA-DTG and DMTA analysis revealed that the presence of 0.02 % PMF-rich extracts enhanced the thermal stability and cross-linking density of the film. Moreover, the incorporation of the PMF-rich citrus extract significantly improved the DPPH radical scavenging rate (increased from 26.22 % to 94.19 %) and antifungal property (against Rhizopus stolonifera in vitro). Furthermore, the inclusion of citrus extracts in the CGP matrix effectively inhibited the deterioration and weight loss of strawberry fruits. Thus, the CGP film incorporated with PMF-rich citrus extract has significant potential as an active packaging material for preserving fresh fruit.

Utilizing sugar factory lime waste and crumb rubber for sustainable Ultra-High-Performance Concrete

Ultra-High-performance Concrete (UHPC) offers significant advancements in construction due to its superior strength and durability. However, its traditional formulation demands extensive cement use, leading to high costs and adverse environmental impacts. This research explores the feasibility of repurposing lime waste, a by-product of sugar production, as a substitute for cementitious materials in UHPC, while also examining the use of crumb rubber powder as a complementary filler within the UHPC matrix. Glass, steel, and synthetic macro fibers are also added to improve the ductility of the concrete mix. A series of mechanical tests are conducted to evaluate the performance of the developed concrete. The results are compared with those of conventional cement and other cement substitutes. It is found that replacing 10 % of cement with lime waste and rubber powder produces the optimal UHPC mix, with 104 MPa compressive strength, 7.1 MPa bending strength, 5.8 MPa tensile strength, and 32.8 GPa modulus of elasticity. Moreover, steel fibers are the best reinforcement option, as they significantly improve the ductility and malleability of the concrete, achieving 13,456 J rupture energy and 17.4 MPa bending strength. However, a microstructure analysis reveals that the cement substitutes cause a slight deterioration in the concrete quality, but this is compensated by the benefits of the fibers. It is also shown that the use of lime waste and rubber powder reduces the carbon footprint and the cost of UHPC, making it a more sustainable and economical choice for construction materials. Therefore, it is concluded that the use of lime waste and rubber powder as cement substitutes in UHPC is a feasible and beneficial strategy for developing environmentally friendly UHPC with enhanced mechanical properties. This study contributes to the advancement of eco-conscious UHPC and opens new avenues for future research.

Investigative studies on natural fiber reinforced composites for automotive bumper beam applications

The automotive sector wants lighter, recyclable, degradable, and sustainable composite materials. In the last few decades, natural fiber composite has been used in a wide range. The natural plant-based fibers are reinforced into polymeric composite materials, giving significant mechanical properties compared to conventional material. This work selects flax and sisal fibers due to higher strength and Young’s modulus. Mechanical behavior such as tensile, flexural, and impact strength are evaluated. Mechanical behavior results are considered in the simulation to determine the performance of an automotive bumper beam. The tensile strength of the flax composite is 90% higher than that of the sisal composite. Flexural strength is 17% higher in a flax composite, whereas energy absorption is nearly identical in a flax and sisal composite. The flax composite has a maximum 204.9 MPa tensile strength, 157.98 MPa flexural strength, and 45 J energy absorption. The mechanical behavior results are validated with simulation results in the ANSYS workbench for static analysis. The results indicate that the flax fiber reinforced composite with 43:57 of a flax-matrix ratio performs better as it can be used as a structural material. A morphological study shows the uniform distribution of matrix material and fiber orientation.

A comparison between tensile and hole expansion properties in 800 MPa tensile strength grade hot-rolled steels

Sheared edge formability can play a critical role in cold forming of high-strength hot-rolled steels due to susceptibility to edge cracking. Standardized ISO 16630 hole expansion test is currently the most widely used method to estimate sheared edge formability of steel sheets, however, there has been increasing interest in the industry to reduce the amount of required testing. The aim of this paper was to compare hole expansion performance of hot-rolled strip steels to various uniaxial tensile test results. The five investigated steels were selected to have 3 mm thickness and similar (838±10 MPa) longitudinal tensile strength level while consisting of different microstructures. Tensile properties were measured in 0°, 45°, and 90° angle relative to the rolling direction to investigate anisotropy. Plastic strain ratios were determined by digital image correlation measurement. Local ductility was evaluated with thickness strain measurements (εp_amin) on fracture surfaces of the tensile specimens. To investigate stretch-flangeability, ISO 16630 conforming hole expansion tests were performed. Test holes were produced by punching and by wire electrical discharge machining (W-EDM) to evaluate edge damage tolerance of the materials. The hole expansion ratios (HER) were not observed to correlate with majority of the investigated tensile test results, such as uniform elongation and yield strength. However, a good correlation between HER and planar anisotropy was observed. Planar anisotropy is seen to affect strain localization tendency around the hole. The HER values of neither punched nor W-EDM specimens correlated clearly with εp_amin measurement results. The results show that at a similar strength level, anisotropy is highly influencing the hole expansion performance of hot-rolled steels, and that the HER is not reliably predicted by a single local formability parameter.

Taguchi Optimization of Wetting, Thermal and Mechanical Properties of Sn-1.0wt.%Ag-0.5wt.%Cu Alloys Modified with Bi and Sb.

This study was conducted on SAC105 (Sn-1wt.%Ag-0.5wt.%Cu) lead-free solder modified with Bi and Sb. The wetting, melting point, and mechanical properties were analysed with the addition of 1~5 wt.%Bi and 1~5 wt.%Sb for SAC105 base alloy. The wetting characteristics were assessed by wetting time (zero cross time, ZCT) obtained from wetting balance tests. The mechanical properties were analysed by tensile tests. Considering two factors (Bi, Sb), a three-level (0, 1, 2 wt.%) design of experiment (DOE) method array was applied for Taguchi optimization. The results indicated that the solder wetting increased as Bi content increased, while it decreased with Sb. The ZCT decreased with increasing Bi content up to 4 wt.%, while it increased proportionally to Sb content. The melting point, measured using a differential scanning calorimeter (DSC), showed that the melting point tended to decrease according to Bi increase, while it increases depending on the Sb content. Increase in Bi and Sb levels resulted in enhanced tensile strength in the mechanical properties tests, with Bi having a more noticeable impact. The Taguchi optimized conditions for the Bi and Sb studies were found to be 2 wt.%Bi and 2 wt.%Sb. This led to an optimal set of 0.9 s of wetting time, a 222.55 °C melting point, a 55 MPa tensile strength, and a 50% elongation.

Entanglement Added to Cross-Linked Chains Enables Tough Gelatin-Based Hydrogel for Zn Metal Batteries.

Currently, it is still challenging to develop a hydrogel electrolyte matrix that can successfully achieve a harmonious combination of mechanical strength, ionic conductivity, and interfacial adaptability. Herein, a multi-networked hydrogel electrolyte with a high entanglement effect based on gelatin/oxidized dextran/methacrylic anhydride, denoted as ODGelMA is constructed. Attribute to the Schiff base network formulation of ─RC═N─, oxidized dextran integrated gelatin chains induce a dense hydrophilic conformation group. Furthermore, addition of methacrylic anhydride through a grafting process, the entangled hydrogel achieves impressive mechanical features (6.8MPa tensile strength) and high ionic conductivity (3.68mScm-1 at 20°C). The ODGelMA electrolyte regulates the zinc electrode by circumventing dendrite growth, and showcases an adaptable framework reservoir to accelerate the Zn2+ desolvation process. Benefiting from the entanglement effect, the Zn anode achieves an outstanding average Coulombic efficiency (CE) of 99.8% over 500 cycles and cycling stability of 900h at 5mAcm-2 and 2.5mAhcm-2. The Zn||I2 full cell yields an ultra-long cycling stability of 10000 cycles with a capacity retention of 92.4% at 5C. Furthermore, a 60mAh single-layer pouch cell maintains a stable work of 350 cycles.

Role of buttering layer composition on microstructural heterogeneity and mechanical properties of Alloy 617 and P92 steel dissimilar welded joints for future Indian AUSC program

Restrictive operating conditions (even exceeding 700 °C) of materials in advanced ultra super critical (AUSC) power plants and the need to minimize manufacturing and maintenance costs require the production of dissimilar metal welded joints (DMW). Significant differences in the physical and chemical properties of welded materials lead to phenomena that reduce the weldability of the metals used and force the search for solutions that limit unfavorable phenomena, e.g., the use of buttering layers. The study presents a comparison of two types of joints with Alloy 617 (UNS N06617) and ferritic P92 (UNS K92460) steel made using Inconel 82 (ENiCrFe-3) and Inconel 617 (ERNiCrCoMo-1) alloys buttering layer and the corresponding chemical composition of filler metals. All areas of the joints made with the gas tungsten arc welding process were subjected to structural investigations (optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) and mechanical tests (microhardness, room and high temperature tensile, and toughness testing). Despite the more complicated welding procedure, sound welded joints were obtained with favorable properties resulting, inter alia, from the reduced thickness of the martensite layer in HAZ of P92 steel and the limited diffusion of alloy components compared to welded joints without the buttering layer. This also resulted in a reduction of the maximum hardness (especially in the case of Inconel 82 buttering—by 15–30 HV0.5 in comparison with Inconel 617 buttering) and an increase in strength while limiting the decrease in plasticity (even 663 MPa tensile strength and 21% of elongation for Inconel 617 buttered joint). Moreover, improved high-temperature performance (approximately 70–100 MPa) of the welded joint following the application of the buttering layer was confirmed. The presented results allow for drawing general conclusions that both proposed welding procedures can be recommended for use in the working conditions occurring at AUSC.

Extraction of cellulose from halophytic plants for the synthesis of a novel biocomposite.

Cellulose nanofibers, a sustainable and promising material with widespread applications, exhibit appreciable strength and excellent mechanical and physicochemical properties. The preparation of cellulosic nanofibers from food or agricultural residue is not sustainable. Therefore, this study was designed to use three halophytic plants (Cressa cretica, Phragmites karka, and Suaeda fruticosa) to extract cellulose for the subsequent conversion to cellulosic nanofibers composites. The other extracted biomass components including lignin, hemicellulose, and pectin were also utilized to obtain industrially valuable enzymes. The maximum pectinase (31.56 IU mL-1), xylanase (35.21 IU mL-1), and laccase (15.89 IU mL-1) were produced after the fermentation of extracted pectin, hemicellulose, and lignin from S. fruticosa, P. karka, and C. cretica, respectively. Cellulose was methylated (with a degree of substitution of 2.4) and subsequently converted into a composite using polyvinyl alcohol. Scanning electron microscopy and Fourier-transform infrared spectroscopy confirmed the successful synthesis of the composites. The composites made up of cellulose from C. cretica and S. fruticosa had a high tensile strength (21.5 and 15.2 MPa) and low biodegradability (47.58% and 44.56%, respectively) after dumping for 3 months in soil, as compared with the composite from P. karka (98.79% biodegradability and 4.9 MPa tensile strength). Moreover, all the composites exhibited antibacterial activity against gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and gram-positive bacteria (Staphylococcus aureus). Hence, this study emphasizes the possibility for various industrial applications of biomass from halophytic plants.

Polymer solid electrolytes with ultra-stable cycles and high-capacity retention for all-solid-state Li-metal battery

Polymer electrolytes have become widely popular on account of their low expenses, reduced weight, simple processing, and excellent safety features. However, polymer electrolytes have yet to find use in commercial batteries because of their limited mechanical durability and poor ionic conductivity. In this paper, an ultra-stable cycles and interfaces blending polymer electrolyte (BPE) suitable for all solid-state Li metal batteries was prepared by blending three polymers: polymethyl methacrylate (PMMA), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), and polyethylene oxide (PEO). Microstructure characterization showed numerous amorphous areas with strong interfacial strength of the BPE. The BPE3 exhibited a maximum of 15.65 MPa in tensile strength. BPE2 have excellent electrochemical performance, such as wide electrochemical windows (up to 4.7 V vs Li/Li+), high lithium ion transference numbers (up to 0.75), high ion conductivity (up to 1.87 × 10-4 S cm−1 at 60 °C), and excellent interface stability. By assembling all state-solid LiFePO4/BPE2/Li batteries for electrochemical testing, BPE2 exhibit high electrochemical characteristics. BPE2 discharge specific capacity is as high as 154.7 mAh g−1 at 1C. The BPE2 underwent 200 cycles at 0.5C and 400 cycles at 1C, with capacity retention rates of 95.7 % and 96.6 %, respectively. BPE is a promising electrolyte candidate for flexible lithium metal batteries.

Ternary systems engineered conductive hydrogel with extraordinary strength, environmental adaptability and excellent electrochemical performances for flexible power supply devices

The easy failure, poor environmental adaptability and unsatisfactory electrochemical performances of hydrogels hinder their applications as key components of flexible power supply devices (PSDs). Herein, a PAA-based hydrogel with extraordinary strength and environmental adaptability is designed via a ternary system, consisting of the tannin-modified MXene (TA@MXene), ZnCl2-cellulose and malic acid (MA) electrolyte. The TA@MXene and ZnCl2-cellulose promote the crosslinking of hydrogel via forming multi networks, endowing the hydrogel with 1.9 MPa tensile strength and 620 % stretchability. Furthermore, the hydrogel has 38.4 mS·cm−1 conductivity, thanks to the effective ion transfer channels in the hydrogel. The MA electrolyte provides a stable pH environment via forming an acid ionization system; also, MA and the high-concentration ZnCl2 solution enhance their electrochemical performance at extreme environments. Three typical PSDs were assembled using the resultant hydrogel as electrolyte/electrode. The as-prepared supercapacitors display a high specific capacity (173.5 mAh·g−1), a superior energy density (208.2 Wh·kg−1) and outstanding capacity retention (92.1 % after 5000 cycles); flexible batteries efficiently respond to strain signals, with 0.77 V open-circuit voltage (Voc); the as-assembled TENG has a 110 V Voc (100 % stretching deformation). We present a design strategy for the construction of advanced hydrogels based a ternary system that will promote flexible PSDs towards practical use.

Biodegradable Zn-2Cu-0.5Zr alloy promotes the bone repair of senile osteoporotic fractures via the immune-modulation of macrophages

Delayed bone-healing of senile osteoporotic fractures remains a clinical challenge due to the alterations caused by aging in bone and immune systems. The novel biomaterials that address the deficiencies in both skeletal cells and immune systems are required to effectively treat the bone injuries of older patients. Zinc (Zn) has shown promise as a biodegradable material for use in orthopedic implants. To address the bone-healing deficiencies in elderly patients with bone injuries, we developed a biodegradable Zn-based alloy (Zn–2Cu-0.5Zr) with enhanced mechanical properties, including a yield strength of 198.7 MPa and ultimate tensile strength of 217.6 MPa, surpassing those of pure Zn and Zn–2Cu alloys. Cytotoxicity tests conducted on bone marrow mesenchymal stem cells (BMSCs) and MC3T3-E1 cells demonstrated that the extracts from Zn–2Cu-0.5Zr alloy exhibited no observable cytotoxic effects. Furthermore, the extracts of Zn–2Cu-0.5Zr alloy exhibited significant anti-inflammatory effects through regulation of inflammation-related cytokine production and modulation of macrophage polarization. The improved immune-osteo microenvironment subsequently contributed to osteogenic differentiation of BMSCs. The potential therapeutic application of Zn–2Cu-0.5Zr in senile osteoporotic fracture was tested using a rat model of age-related osteoporosis. The Zn–2Cu-0.5Zr alloy met the requirements for load-bearing applications and accelerated the healing process in a tibial fracture in aged rats. The imaging and histological analyses showed that it could accelerate the bone-repair process and promote the fracture healing in senile osteoporotic rats. These findings suggest that the novel Zn–2Cu-0.5Zr alloy holds potential for influencing the immunomodulatory function of macrophages and facilitating bone repair in elderly individuals with osteoporosis.

Improving the Properties of Gelatin-Based Films by Incorporation of "Pitanga" Leaf Extract and Crystalline Nanocellulose.

Biopolymer-based films can be activated by the incorporation of active compounds into their matrix. Plant extracts are rich in phenolic compounds, which have antimicrobial and/or antioxidant properties. The aim of this study was to produce gelatin-based active films and nanocomposite films incorporated with "pitanga" (Eugenia uniflora L.) leaf extract (PLE) and/or crystalline nanocellulose extracted from soybean straw (CN), and to study the physicochemical, functional, microstructural, thermal, UV/Vis light barrier, and antioxidant properties of these materials. PLE enhanced some film properties, such as tensile strength (from 30.2 MPa to 40.6 MPa), elastic modulus (from 9.3 MPa to 11.3 MPa), the UV/Vis light barrier, and antioxidant activity, in addition to affecting the microstructural, surface, and color properties. These improvements were even more significant in nanocomposites simultaneously containing PLE and CN (59.5 MPa for tensile strength and 15.1 MPa for elastic modulus), and these composites also had lower moisture content (12.2% compared to 13.5-14.4% for other treatments) and solubility in water (from 48.9% to 44.1%). These improvements may be the result of interactions that occur between PLE's polyphenols and gelatin, mainly in the presence of CN, probably due to the formation of a stable PLE-CN-gelatin complex. These results are relevant for the food packaging sector, as the activated nanocomposite films exhibited enhanced active, barrier, and mechanical properties due to the presence of PLE and CN, in addition to being entirely produced with sustainable components from natural and renewable sources.

Tensile, flexural, and mode-I cracking behavior of interpenetrating phase composites (IPC), developed using additively manufactured PLA-based structures with different infill densities and epoxy resin polymer as matrix

Interpenetrating phase composites (IPC) materials are designed to combine the advantages of made-from materials or develop an intended behavior. Recently, the use of 3D printed structures has received attention due to advantages, such as the rapid and cheap prototyping techniques of complex structures. However, most materials, such as polylactic acid (PLA) used for conventional 3D printing, have low strength and insignificant durability. To overcome these issues, the excellent characteristics of polymer adhesives, such as epoxy resin, can be used to increase their strength and durability. In this paper, PLA-based 3D printed samples and epoxy resin adhesive were merged to develop an interpenetrating phase composite. The samples were printed with 25, 50, 75, and 100 infill percentages and tested in direct tensile, bending, and mode-I fracture. From the results, it can be seen that reducing the infill percentage to 75, 50, and 25 % reduces the tensile strength to 16, 9, and 3 MPa (−40 %, −66 %, and −90 % compared to the sample with 100 % infill with 26 MPa strength), adding epoxy resin to develop an IPC, results in 24, 29 and 32 MPa tensile strength. Compared to 3D-printed parts with the same infill percentages, the IPCs have 150, 320, and 1140 % higher tensile strengths, respectively. Also, the failed samples were reviewed by scanning electron microscope.

Experimental study and characterisation of 316L stainless steel parts fabricated with metal fused filament fabrication

The 3D printing process of Fused Deposition Modelling (FDM) can be used for fabricating metal parts without the need of mold. Metal Material Extrusion uses metal-polymer composite filament in the 3D printer to extrude the green part, then a de-binding process for removing the polymer binder, and eventually, the sintering process under high temperatures for making a metallic part. A comprehensive research is conducted in which sintering parameters including heating rate, dwell time, and sintering atmospheres are varied for metal parts mechanical characteristics including tensile strength, ductility, and density. Moreover, sintering atmospheres including vacuum and argon are taken into consideration in this research study. The metal part is known as silver part which has exhibited a high mechanical strength of 540 MPa, a considerable density of 7.57 g/cm3, and a high hardness of 220 HV under a vacuum sintering atmosphere. Whereas the metal parts produced under argon atmosphere have shown comparatively low mechanical strength 424 MPa, density 7.1 g/cm3 and 177 HV. The results are compared with an industrial benchmark process where catalytic de-binding and sintering are used to achieve 500 MPa tensile strength, density 7.83 g/cm3, and 175 HV. Scanning Electron Microscopy reveals that grains are coarsened in a vacuum, and grains appear peeled off along with small pores in the boundaries. The industrial benchmark part has uniform and finer grains.

Study on the mechanical properties and deformation mechanism of copper with different volume fractions of gradient structure

In this study, ultrasonic rolling process (USRP) were performed on the rolled copper samples (with an initial grain size of 11.4 μm) to obtain the gradient structure (GS), which comprises nanocrystalline layer (NL), deformed layer (DL), and center layer (CL). The different GS layer (NL and DL) volume fractions of samples were obtained by performing different passes of USRP after rolling, and the effect of the GS layer volume fractions on the mechanical properties was further studied. The morphology and structure of (unrolled, rolled and rolled + USRP) samples were characterized by electron backscattering diffraction (EBSD) and transmission electron microscope (TEM). In-situ tensile testing was used to investigate the tensile deformation behavior of the GS sample. The results show that the rolled + USRP (12 passes) sample with the thickest GS layer (volume fraction of 42%) has the greatest strength (yield strength (YS) 262 MPa and ultimate tensile strength (UTS) 325 MPa). The fine grains, dislocations and textures jointly strengthen the GS sample by increasing the force required for dislocation slip, and their contribution to YS is 51.3%, 44.4% and 4.3%, respectively. In addition, the nanocrystalline grains of GS layer make microcracks evenly distributed and hard to gather, to efficiently hinder cracks propagation and result in good ductility of GS samples. This study provides an effective method to obtain GS materials with good comprehensive properties and a deeper understanding of their deformation behavior and strengthening mechanism.