Good Compressive Properties Research Articles

Preparation of TiNbTaZrMo high-entropy alloy with tunable Young's modulus by selective laser melting

Biological high-entropy alloy (Bio-HEA) is a new generation of biomedical alloys with excellent mechanical properties and good biocompatibility. However, elemental segregation often exists during conventional casting or arc melting, which dramatically degrades their mechanical performance. Here, we utilized the selective laser melting (SLM) technique to fabricate dense blocks with low Young's modulus and good compression property at room temperature. Then, we fabricated HEA with triply periodic minimal surface (TPMS) lattice, which has Young's modulus (6.71–16.21 GPa) very close to that of human trabecular bone. This structure provides the possibility of meeting the requirement of various bone implants by customizing the shape and porosity of the TPMS lattice, affirming the possibility of Bio-HEA for biomedical applications.

Method of Starch Acetylation and Use of Acetylated Starch as Polymer in Pharmaceutical Formulations

Starch is used as a key polymer in pharmaceutical industries since long back for various purposes such as binder, disintegrating agent, bulking agent, film former and many more. But as per the purpose of dosage forms it’s used get changed. Currently scientists are more focused on controlled and sustained release dosage forms. Since, native starch does not meet up the demand of controlled or sustained release, so there is need of modifying the polymer as per dosage form requirement. Modification of starch can be done by physical, chemical, enzymatic, and genetic method. Among all, the current article is focusing on chemical modification of starch, especially the acetylation. Acetylation of starch can be done using different acetylating agent such as acetic anhydride (AA), and glacial acetic acid etc. and sodium hydroxide (NaOH), pyridine and sulphuric acid etc as a catalyst. The native structure of starch can be less efficient, since its functional properties are less stable to process condition such as high temperature, shear stress and exposure to acidic media, which decreases its use in industrial application. Acetylated starches facilitate higher stability and resistance to retrogradation or crystallization, enhanced granular size, swelling power, and water absorption capacity, which provides good flow and compression properties. It reduces the pasting temperature and solubility. It makes the acetylated starch as a good candidate for customizing the overall performance of native starch, which may be used as the controlled release or sustained release polymer in pharmaceutical dosage form.

Feasibility of improving wastewater sludge dewaterability by combination of cationic polyacrylamide and synthetic fibers for resource utilization

As a by-product of wastewater treatments, sewage sludge possesses great value but its high moisture content impedes the resource recovery. Chemical conditioners are required prior to mechanical dewatering, and they are important in dewatering operations. On the other hand, synthetic fibers have good compression properties and can help sludge to build qualified sludge cake in mechanical dewatering process. In this study, we investigated the synergistic effects between CPAM and synthetic fibers, which could improve the wastewater sludge dewaterability and resource utilization. The sludge water content decreased from 96.2 % to 65.9 % after conditioning with the combination of CPAM at 1 mg∙g−1 DS combined with PP at 0.15 g∙g−1 DS. The combination of CPAM and fiber increased the zeta potential of sludge from −12.5 mV to −5.12 mV and decreased the compressibility coefficient of sludge cake from 1.13 to 0.89, achieving the effect of destabilizing the system and enhancing the rigidity of sludge cake. EPS analysis showed that the association of CPAM with fiber acted as an aid to dewatering mainly through the disruption of TB-EPS. In addition, the dry basis calorific value (35%) reached 6676 kJ∙kg−1, indicating the feasibility of subsequent resource utilization. In conclusion, this study provided a new method and its underlying theory for deep sludge dewatering and wastes reutilization.

The effect of elastic yarn tension and alignment on the tensile and compression characteristics of weft-knitted spacer fabrics for cushioning applications

Spacer fabrics are good candidates as cushioning materials in protective clothing and equipment. They demonstrate good compressive properties and energy absorption, which makes them suitable for human body protection. The cushioning performance of these fabrics is highly affected by the compression characteristics of the fabric. This research aims to improve the compression properties of spacer fabrics by incorporating elastic yarns with various tensions and alignments in the surface layers of the fabric. The results reveal that the presence of spandex yarn in the surface layers of the spacer fabric, as well as increasing the tension of spandex yarn, enhances the absorbed energy and dissipated compression energy while decreasing the resiliency, thickness change, and thickness recovery of the fabric. Moreover, increasing the number of miss stitches of spandex yarn decreases the energy absorption and dissipated compression energy while it increases the thickness change and thickness recovery of the fabric. Eventually, the utilization of elastic yarns under higher tension and fewer miss stitches in the surface layers of spacer fabrics improve the cushioning function of spacer fabrics.

The partial renovation of old factory buildings - Performance study of the inorganic vitrified micro-bubble external wall insulation system

This paper took the partial renovation project of an old factory building in Wuhan as an example to study its external wall insulation system. A new insulation system was designed based on inorganic vitrified micro-bubbles. The material was briefly analyzed. The performance of the new insulation system was detected by designing test specimens. The results found that the specimens had good compressive, tensile and flexural properties, reaching the standard of A1 grade of construction materials, the specimens were non-combustible, and the temperature change of the concrete base was stable under the action of heating-cooling and heating-rain cycles, suggesting good thermal insulation performance. The results verify the effectiveness of the insulation system. The insulation system can be better applied in practice.

Study on the NiTi shape memory alloys in-situ synthesized by dual-wire-feed electron beam additive manufacturing

In this study, NiTi shape memory alloys were in-situ synthesized by dual-wire-feed electron beam additive manufacturing (dual-wire EBAM), which uses electron beam as energy source working in the vacuum environment, and uses pure Ni and Ti wires as feedstock. Microstructures, chemical composition distribution and mechanical properties of the as-built NiTi alloys were studied. Results showed that the as-built NiTi part exhibited continuous coarse columnar grains all along the building direction. Uniform composition distribution was obtained away from the substrate in the upper and middle regions of the part, which consisted of dominant NiTi phase and exhibited typical one-stage martensitic phase transformation. Good static compressive property with an ultimate compressive strength of 2.9 GPa and a fracture strain of 34.2% were obtained. The as-built NiTi samples also demonstrated good shape memory response, which had recovery rates of 88%, 83%, 81%, 80% and 63% for pre-compressive deformation strains of 2%, 3%, 4%, 5% and 6%, respectively. This study showed that the dual-wire EBAM has great potential to in-situ synthesize NiTi alloys with typical thermomechanical response and to flexibly control the chemical composition and corresponding functional performance of target NiTi alloy components by regulating the feeding speeds of Ni wire and Ti wire independently.

Analisis Pengaruh Penambahan Kaolin Sebagai Subtitusi Semen Terhadap Kuat Tekan Beton Ringan

Concrete is a very important construction material and has good compressive properties. According to its mass, concrete is divided into ordinary concrete and lightweight concrete. Light weight concrete is 1000-2000 kg/m3. In high construction projects the use of lightweight concrete can reduce the mass of the building itself. The latest innovation in lightweight concrete is the addition of kaolin as a cement substitute. Kaolin is a clay or clay mineral that contains a lot of aluminum silica. Stryofoam is one of the materials that can be used in lightweight concrete mixes. The use of kaolin and styrofoam waste is sought to support construction materials that are more environmentally friendly. The purpose of this study was to determine the effect of the addition of kaolin on compressive strength so that it can be used as an admixture in lightweight concrete. The results showed that the weight of concrete mixed with 5%, 10%, 15% kaolin and 60% Styrofoam at the age of 28 days was 1836 kg/m³, 1845 kg/m³, 1852 kg/m³. The average compressive strength for the kaolin variants 5%, 10%, 15% were 8.28 MPa, 8.46 MPa, 10.11 MPa. Based on this it was concluded that concrete using a mixture of kaolin and 60% stryofoam can be used in light construction. Because the weight of the lightweight concrete tested was lower than normal concrete and met the specified requirements, namely the specific gravity of the resulting concrete was in the range of 1000-2000 kg/m³.

Gum Arabic as an Admixture in Modified Concrete Mixed with Calcined Kaolin

The use of calcined kaolin (CK) as a cementitious material in construction has attracted the interest of various researchers due to its environmental, mechanical, and physical qualities, all of which contribute to the lowering of cement usage. Studies have reported numerous problems associated with its use in concrete, apart from the ecological benefit that CK can provide. For instance, there is an issue of increased water demand due to smaller particle size, which generates much more heat in concrete, which has a detrimental effect on the mechanical and physical properties of concrete. This paper presents the analysis of an investigation aimed at using gum Arabic (GA) as a biopolymer admixture and calcined kaolin as a partial replacement of cement to improve the mechanical properties and durability of concrete. GA proportions ranged from 0 to 1% by weight of cement. Calcined kaolin (CK) was used to replace 5, 10, 15, 20, 25, and 30% of the cement content, respectively. Compressive strength, splitting tensile strength, density, strength loss, and weight loss tests were all performed to validate the structural performance of the modified concrete. The compressive tests, performed after 28 days from the time the mixture was made, demonstrated that the maximum percentage of CK that could replace cement without affecting the mechanical properties of concrete was 20%. Beyond 20%, concrete does not exhibit good compressive strength properties. The results also revealed decreased compressive strength and splitting tensile strength tests as the percentage of CK increased. After 56 days, compressive strength at 5% CK and 10% CK increased slightly by 0.743% and 1.162 %, respectively, compared to the control sample. The inclusion of 0.8%GA increased the compressive strength by 8.94% compared to the control sample (0%CK + 0%GA + 100%OPC) after 56 days. The results of durability tests showed that 0.6% GA had a higher compressive strength than other percentages containing GA. Doi: 10.28991/CEJ-2022-08-05-010 Full Text: PDF

Interfacial π-π Interactions Induced Ultralight, 300 °C-Stable, Wideband Graphene/Polyaramid Foam for Electromagnetic Wave Absorption in Both Gigahertz and Terahertz Bands.

High-performance electromagnetic wave-absorbing (EMA) materials used in high-temperature environments are of great importance in both civil and military fields. Herein, we have developed the ultralight graphene/polyaramid composite foam for wideband electromagnetic wave absorption in both gigahertz and terahertz bands, with a higher service temperature of 300 °C. It is found that strong interfacial π-π interactions are spontaneously constructed between graphene and polyaramids (PA), during the foam preparation process. This endows the foam with two advantages for its EMA performance. First, the π-π interactions trigger the interfacial polarization for enhanced microwave dissipation, as confirmed by the experimental and simulation results. The composite foam with an ultralow density (0.0038 g/cm3) shows a minimum reflection loss (RL) of -36.5 dB and an effective absorption bandwidth (EAB) of 8.4 GHz between 2 and 18 GHz band. Meanwhile, excellent terahertz (THz) absorption is also achieved, with EAB covering the entire 0.2-1.6 THz range. Second, the interfacial π-π interactions promote PA to present a unique in-plane orientation configuration along the graphene surface, thus making PA the effective antioxidation barrier layer for graphene at high temperatures. The EMA performance of the foam could be completely preserved after 300 °C treatment in air atmosphere. Furthermore, the composite foam exhibits multifunctions, including good compressive, thermal insulating, and flame-retardant properties. We believe that this study could provide useful guidance for the design of next-generation EMA materials used in harsh environments.

Tečno-čvrsti sistemi kao novi pristup razvoju formulacija i proizvodnji čvrstih farmaceutskih oblika lekova - izazovi i perspektive

Liquisolid systems are a novel, promising platform for the production of solid dosage forms with a high liquid content, i.e. dispersion of the drug in a suitable, hydrophilic, non-volatile liquid vehicle or liquid drug. This technology requires conventional, but highly porous excipients (carrier and coating material in the appropriate ratio) able to absorb/adsorb liquid medication, resulting in both good flowability and acceptable compression properties. This approach has shown great potential to improve the dissolution rate and bioavailability of poorly soluble drugs, and has been recognized as a good alternative to common, more complex and expensive techniques. A variety of applications of this simple technique have been investigated recently, including the preparation of: modified release tablets, orally disintegrating tablets, solid dosage forms with liquid herbal extracts, etc. This emerging technology has numerous advantages, and the most important are: simplicity, cost-effectiveness, applicability in large scale production and environmental friendliness. However, it is accompanied by certain challenges as well, such as limited applicability in the case of highly dosed drugs. This article aims to give a comprehensive overview of recent progress regarding the potential applications of this technology, as well as to give an insight into the new liquisolid-based techniques intending to further support its commercial applicability.

Valorization of Recycled Tire Rubber for 3D Printing of ABS- and TPO-Based Composites.

Vulcanized and devulcanized ground tire rubber microparticles have been used as a minor phase in acrylonitrile butadiene styrene copolymer (ABS) and thermoplastic polyolefins (TPO) for the development of materials with desired functionalities by 3D printing. These polymers have been selected because they (i) present part of the plastic waste generated by the automotive industry and (ii) have totally different properties (ABS for its stiffness and robustness and TPO for its softness and ductility). The study aims to improve the circular economy of the automotive industry by proposing a promising route for recycling the generated tire rubber waste. In this respect, emergent technology for plastic processing such as 3D printing is used, as part of the additive manufacturing technologies for the prolongated end of life of recycled plastics originated from automotive waste such as ABS and TPO. The obtained results revealed that (i) the composites are suitable for successful filament production with desired composition and diameter required for successful 3D printing by fused deposition modeling, and that (ii) the optimization of the composition of the blends allows the production of materials with interesting mechanical performances. Indeed, some of the investigated ABS-recycled rubber tire blends exhibit high impact properties as TPO-based composites do, which in addition exhibits elongation at break higher than 500% and good compression properties, accompanied with good shape recovery ratio after compression.

Improvement of mechanical properties of zein porous scaffold by quenching/electrospun fiber reinforcement

As a novel bone substitute material, zein-based scaffolds (ZS) should have suitable mechanical properties and porosity. ZS has shown good compressive properties matching cancellous bone, but there is still a demand to improve its mechanical properties, especially tensile and bending properties without adding plasticizers. The present study explored two simple and environment-friendly factors for this purpose: fiber reinforcement and quenching. Addition of electrospun zein fibers enhanced all mechanical properties significantly including compressive, tensile, and bending moduli; compressive and bending strengths of ZS with both higher (70–80%) and lower (50–60%) porosities, no matter whether heating treated or not treated. Especially, all these parameters were further enhanced significantly by addition of heating treated fibers. AFM provided evidence that high temperature modification could significantly alter the micro-elastic properties of zein electrospun fibers, i.e., increased stiffness of fibers. Quenching treatment also enhanced compressive, tensile, and bending strengths significantly. Finally, quenching treated ZS were implanted into critical-sized bone defects (15 mm) of the rabbit model to compare the repair efficacy with a commercial β-tricalcium phosphate product. The results demonstrated that there were no remarkable differences in bone reconstructions between these two materials.

Mechanical and energy absorption properties of the composite XX-type lattice sandwich structure

In this paper, two types of the composite XX-type lattice sandwich structure (XX (Ⅰ) and XX (Ⅱ)) were made of panels (medium-density fiberboard and plywood) and core (birch) by using a type of insertion-glue method. An out-of-plane compressive test and a short beam shear test were carried out to investigate the failure modes, mechanical and energy absorption properties of the composite XX-type lattice sandwich structure. Results showed that the compression and short beam shear failure modes of composite XX-type lattice sandwich structure were mainly the shear failure of the core and the failure of panels. The sandwich structure with the core diameter of 8 mm had good compression property. The XX (Ⅱ)-type lattice sandwich structure of the combination of Plywood + birch had better compression, short beam shear, and energy absorption properties. The combination of MDF + birch was more suitable for the compressive theoretical model.

Microstructures and Mechanical Properties of Al-Ti-Zr-Nb-Ta-Mo-V Refractory High-Entropy Alloys with Coherent B2 Nanoprecipitation

In this work, the microstructural evolution and mechanical properties of new body-centered cubic (BCC)-based Al-Ti-Zr-Nb-Ta-Mo-V refractory high-entropy alloys (RHEAs) with coherent B2 precipitation are investigated. These designed alloy ingots were solid-solutionized at 1573 K for 2 h and then aged at 873 K for 24 h, in which each treatment was followed by water quenching. It was found that there exists phase separation of BCC matrix, Ti/Zr-rich BCC1 and Nb/Ta-rich BCC2 in these alloys. Moreover, ultra-fine spherical B2 nanoparticles with a size of 3~5 nm were dispersed in BCC2 matrix. These B2 nanoparticles could be coarsened up to 25~50 nm after aging and the particle morphology also changes to a cuboidal shape due to a moderate lattice misfit (ε = 0.7~2.0%). Also, Zr5Al3 phase could coexist with the B2 phase, where the difference between them is that the Ti element is enriched in B2 phase, rather than in Zr5Al3. Among them, the solutionized Al2Ti5Zr4Nb2.5Ta2.5 RHEAs exhibit good compressive mechanical property with a high yield strength of 1240 MPa and a large plasticity, which is mainly attributed to the coherent precipitation in the BCC matrix.

Sustainable, Highly Efficient and Superhydrophobic Fluorinated Silica Functionalized Chitosan Aerogel for Gravity-Driven Oil/Water Separation.

A superhydrophobic fluorinated silica functionalized chitosan (F-CS) aerogel is constructed and fabricated by a simple and sustainable method in this study in order to achieve highly efficient gravity-driven oil/water separation performance. The fluorinated silica functionalization invests the pristine hydrophilic chitosan (CS) aerogel with promising superhydrophobicity with a water contact angle of 151.9°. This novel F-CS aerogel possesses three-dimensional structure with high porosity as well as good chemical stability and mechanical compression property. Moreover, it also shows striking self-cleaning performance and great oil adsorption capacity. Most importantly, the as-prepared aerogels exhibits fast and efficient separation of oil/water mixture by the gravity driven process with high separation efficiency. These great performances render the prepared F-CS aerogel a good candidate for oil/water separation in practical industrial application.

Analysis on hot deformation and following cooling technology of 25Cr2Ni4MoVA steel

The true stress–true strain curves of 25Cr2Ni4MoVA steel were obtained by uniaxial compression experiments at 850–1200 °C in the strain rate range of 0.001–10.0 s−1. And the dynamic continuous cooling transformation curves were obtained at the cooling rate range of 0.5–15.0 °C s−1 from the austenitization temperature of 1000 °C to the room temperature by pre-strain of 0.2 as well. The power dissipation map and the dynamic continuous cooling transformation diagram were constructed based on the data provided by these curves. Compared with the optical micrographs of the compressed samples, the full dynamic recrystallization region is located between 1000 and 1200 °C and at the strain rate range from 0.01 to 10.0 s−1 with the power dissipation efficiency not less than 0.33. In the full dynamic recrystallization region, the power dissipation efficiency increases and the dynamic recrystallization activation energy decreases with the temperature increasing. With the strain rate decreasing, the power dissipation efficiency increases firstly and then starts to decrease as the strain rate is less than 0.1 s−1, and dynamic recrystallization activation energy changes on the contrary. According to the dynamic continuous cooling transformation diagram, slow cooling is a better way for the hot-deformed piece with large size or complex shape to avoid cracking as the temperature of the piece is lower than 400 °C, and different cooling ways can be used for the hot-deformed piece with small size and simple shapes to obtain certain microstructure and meet good compressive properties.

Ferulic acid loaded microspheres reinforced in 3D hybrid scaffold for antimicrobial wound dressing

Here we report the preparation of biomimetic fibrin/chitosan/keratin hybrid scaffolds with a synergistic combination of ferulic acid loaded silica microspheres for antimicrobial wound dressing applications. The infrared and X-ray powder diffraction studies confirm the homogenous nature of the prepared hybrid scaffolds without any major interactions between the constituents. The developed hybrid scaffolds show good thermal, porosity, compression and water uptake properties. Scanning electron microscopic analysis shows that the as-synthesized ferulic acid loaded silica microspheres exhibit an average size of 35 ± 10 μm and also exposes the smooth surface with interconnected porosity in the prepared hybrid scaffolds. The incorporated ferulic acid loaded silica microspheres hybrid scaffolds show effective antimicrobial activity against the common wound pathogens. In vitro NIH3T3 fibroblast cell culture and drug release studies reveal that the prepared hybrid scaffolds have enhanced cell proliferation and adhesion with a prolonged drug release for about 72 h. In vitro wound healing and actin cytoskeleton analysis reveal that the incorporated ferulic acid loaded silica microspheres in fibrin/chitosan/keratin hybrid scaffolds facilitates cell growth and migration to damaged area through cell-cell interactions. These results suggest that the prepared hybrid scaffolds with ferulic acid loaded silica microspheres have great potential for soft tissue engineering applications particularly for the treatment of chronic and infected wounds.

3D-cubic interconnected porous Mg-based scaffolds for bone repair

Abstract Mg-based porous materials, as potential bone tissue engineering scaffolds, are considered an attractive strategy for bone repair owing to favorable biodegradability, good biocompatibility and suitable mechanical properties. In this work, 3D-cubic interconnected porous Mg–xZn–0.3Ca (x = 0,3,6) scaffolds were prepared to obtain desirable pore structures with a mean porosity up to 73% and main pore size of 400–500 µm, which pore structures were close to the human cancellous bone. The structure–property relationships in the present scaffolds were analyzed by experiments and theoretical models of generalized method of cells (GMC). Mg–xZn–0.3Ca scaffolds exhibited good compression properties with a maximum above 5 MPa in yield strength and about 0.4 GPa in elastic modulus. This was attributed to not only the alloy strengthening but also the large minimum solid area. On the other hand, the scaffolds showed undesirable and relatively serious degradation behavior in Hank's solution, resulting from Zn addition in Mg-based scaffolds and the high surface area ratio in the pore structure. Therefore, surface modifications are worth studying for controlled degradation in the future. In conclusion, this research would explore a novel attempt to introduce 3D-cubic pore structure for Mg-based scaffolds, and provide new insights into the preparations of Mg-based scaffolds with good service performances for bone repair.

Effect of MWCNT Surface Functionalisation and Distribution on Compressive Properties of Kenaf and Hybrid Kenaf/Glass Fibres Reinforced Polymer Composites.

The aim of this study is to evaluate the effect of surface treated multi wall carbon nanotubes (MWCNTs) on compressive properties of the unidirectional (UD) kenaf and hybrid woven glass/UD kenaf fibre reinforced polymer composites. The MWCNTs were first treated using concentrated acid (a mix of H2SO4 and HNO3) and silane (three-aminoprophyltriethoxysilane) in order to improve the dispersion within the epoxy matrix using a high shear roll milling technique. In this study, nanomodified epoxies were prepared using 0.5, 0.75 and 1.0 wt % of pristine MWCNT (PCNT), acid treated MWCNT (ACNT) and silane treated MWCNT (SCNT). These nanomodified epoxies were then used for the fabrication of kenaf and hybrid composites using combination of filament winding and resin impregnation. The uniaxial compression test was conducted using a universal testing machine according to the ASTM D3410 standard. The morphology of fractured samples was observed and analysed using scanning electron microscopy (SEM) in order to evaluate the failure behaviour and mechanisms involved during compression. It was found that the addition of treated MWCNT (ACNT and SCNT) improved the compressive properties of kenaf and hybrid composites as compared to those of untreated-MWCNT (PCNT). The addition of 1.0 wt % of SCNT exhibited good compressive properties in both kenaf and hybrid composite systems. The compressive modulus and strength increased by 73.25% and 20.15%, respectively, for composites made of 1.0 wt % SCNT and Kenaf (1.0SCNT/K). For the hybrid composites, the compressive modulus and strength increased by 21.18% and 7.73% for composites made of 1.0 wt % SCNT filled G/K composites (1.0SCNT/G/K).

Fabrication and mechanical characterization of CFRP X-core sandwich panels

A hot-press molding technique is developed to design and manufacture carbon fiber reinforced polymer (CFRP) X-core sandwich panels that allowed both the composite face sheets and its X-core to be simultaneously molded together. Compression tests were performed on the sandwich panels to assess the effects of relative density on its compressive properties and the failure mode that it develops. Analytical models were developed to predict the panel stiffness and strength; and a failure map of its deformation mode is generated based on the geometric parameters of the unit cell. Linear and nonlinear finite element analyses were performed to further investigate the effects of initial geometric imperfection and progressive damage on the response of the sandwich panels with different cell wall slenderness. Predictions from analytical and numerical models will be shown to be in good agreement with the experiments. The CFRP X-core sandwich panels will be shown to attain good compressive properties that are comparable to typical high strength cellular materials, which will be potentially useful for lightweighting applications.