Bending Modulus Of Elasticity Research Articles

Preparation and performance of C/Ta4HfC5-SiC composite fabricated by PIP combined with RMI process

Based on self-made Ta4HfC5 precursor, C/Ta4HfC5-SiC composite material were prepared by precursor impregnation and pyrolysis (PIP) combined with reactive melting infiltration (RMI) process. The density and open porosity of C/Ta4HfC5-SiC composite material are 2.71 ± 0.73 g/cm3 and 7.07 ± 1.29 %, respectively. Pores are distributed at multiple levels, including primarily nanopores below 40 nm, micropores between 0.04 - 8.5 μm, and a small number of macropores between 10 - 285 μm. The Ta4HfC5 phase exists in two forms: dispersed particles in the matrix and a "layered interface" on the surface of fibers within the bundle. The average bending strength, elastic modulus and fracture toughness of C/Ta4HfC5-SiC composite are 84.24 ± 8.71 MPa, 16.13 ± 5.42 GPa and 3.62 ± 0.63 MPa∙m1 /2, respectively, showing a clear brittle fracture mode during the test. The line ablation rate and mass ablation rate of 60 s assessed by the oxyacetylene flame were 7.20 ± 0.35 μm/s and 10.84 ± 0.84 mg/s, respectively. The oxidation products such as Ta2O5, HfO2, Ta(Hf)CxOy formed by Ta4HfC5 phase during ablation present as thicker oxide layers, forming the main anti-ablation components.

Some physical and mechanical properties of particle boards produced with hazelnut husk and astragalus (Astragalus membranaceus) plant

In this study, under laboratory conditions, hazelnut husk and astragalus plant were mixed separately into black pine wood chips, and multi-purpose boards were produced from the obtained chips with urea formaldehyde glue. After the hazelnut husk and astragalus plant were dried and ground, they were added to the chip and glue mixture in certain proportions. Hazelnut husk mixture ratios were applied as 100 %; 0 %, 75 %; 25 %, 50 %; 50 %, 25 %; 75 %, 0 %; 100 % to black pine wood chip in the particle board mixture. These ratios were made in the same way for the astragalus plant. From these mixtures, chipboard blanks of 16 mm thickness and densities between 0,68 g/cm3 and 0,72 g/cm3 were produced. Density, moisture content, thickness increase, water intake, bending strength, modulus of elasticity in bending and tensile strength perpendicular to the surface were tested in physical and mechanical experiments. According to the results obtained, as the participation rate of hazelnut shells and astragalus increased, the durability properties of the panels decreased. At the same time, it shows that the technological properties of the panels produced by adding up to 25 % astragalus plant and hazelnut shells to the mixture comply with the standards.

Experimental study on the improvement of bamboo properties using amide polymer repair material based on the principle of self-energy dissipation

Traditional bamboo and wood components have different holes due to their own and external factors, and the appropriate hole repair technology is the key to improve the component's energy dissipation capacity. In this paper, based on the principle of in-situ free radical polymerization and hollow glass microsphere (HGM) reinforced polymer, PAM hydrogel (PAMHG) with better deformation recovery ability and PAM/HGM amide polymer (AP) with better mechanical properties were prepared. Based on the principle of self-energy dissipation of components, AP is used to improve the deformation capacity of hollow bamboo. The ratio of PAMHG and AP was optimized by single factor test and orthogonal test. The performance of AP was verified by bending test, SEM, energy consumption analysis，durability test and statistical analysis of small diameter round bamboo. The size of the bamboo sample is 250 mm (L)×15 mm (D)×2.5 mm (t), in accordance with LY/T 3347–2023 " Testing methods for physical and mechanical properties of small diameter round bamboo " (China). The results showed that an appropriate amount of glycerol could effectively improve the volume stability of the hydrogel. HGM effectively improved the strength of the polymer, and when the mass ratio of HGM/PAM was 0.48, the maximum compressive strength was 0.8 MPa, which was 2.4 times higher than that of the undoped HGM, and at this time, the optimal polymer ratios were 25 g of AM, 1 g of MBA, 0.01 g of APS, 2 g of TEA, 2 g of Carbomer SF-1, a volume ratio of 1:1 of glycerol/deionized water that the dispersion medium was 70 ml, and HGM was 12 g. The average energy dissipation of grouted bamboo at ultimate load was 2.02 times that of the control group, and the highest bending strength and elastic modulus were 128.01 MPa and 11.24 GPa, which were 41.39 % and 39.75 % higher than that of the control group, respectively. The SEM results revealed that the AP partially prepolymerized solution could infiltrate into the cells and pores of the bamboo material to achieve filling, bonding, as well as reinforcing the bamboo tissue. In addition, the durability test shows that AP has good resistance to environmental pressure. The results of this paper can provide a reference for the restoration materials of bamboo and wood components.

Composites with Synergistically Enhanced Thermodynamic and Mechanical Properties for Geothermal Heat Exchangers

Geothermal energy, derived from the radioactive decay of elements within the Earth's core, is a renewable and clean energy source. The extraction of geothermal energy primarily depends on ground heat exchangers. To address the issue of incompatibility between corrosion resistance, high thermal conductivity, and mechanical performance in current ground heat exchangers, this study develops composites (PEPOE/SCA@SiC) composed of high‐density polyethylene (HDPE) modified with toughener polyethylene‐octene copolymer elastomer (POE) and silicon carbide (SiC) crystals modified with γ‐aminopropyltriethoxysilane (SCA). HDPE offers excellent corrosion resistance, SiC crystals provide efficient phonon transport, and SCA improves the interface compatibility of the composite. The thermal conductivity of PEPOE/SCA@SiC reaches 3.83 W m−1K−1, with a maximum tensile strength of 20.3 MPa, a tensile elastic modulus of up to 498 MPa, and a maximum bending stress of 22.2 MPa with a bending elastic modulus of 561 MPa. Corrosion resistance tests indicate no signs of corrosion in PEPOE/SCA@SiC when exposed to geothermal simulation fluids at 90 °C for 30 days. This study demonstrates that PEPOE/SCA@SiC composites have substantial potential for application in ground heat exchangers, offering promising prospects for advancing sustainable use of geothermal energy and environmental protection.

EVALUATION OF PROPERTIES OF WOOD PLASTIC COMPOSITES MADE FROM SEVEN TYPES OF LIGNOCELLULOSIC FIBERS

This article aims to investigate the characteristics of wood plastic composites (WPC) prepared from polyethylene (PE) reinforced with lignocellulosic fibers derived from the xylem and bark of Masson pine, fir, cypress, as well as from Moso bamboo. The surface polarity and elemental composition of fibers were determined through contact angle measurements and X-ray photoelectron spectroscopy (XPS). The lignocellulosic fiber/PE composites were manufactured through hot-pressing technique, and their water absorption, mechanical properties, and mildew resistance were evaluated. The results revealed that the surface free energy of xylem fibers was higher than that of bark fibers among the three conifer species. XPS analysis showed that the O/C ratio of bark was consistently lower than that of xylem fiber. Among the three conifers, the Masson pine bark had the lowest O/C ratio (22.25%), while its xylem fibers had the highest ratio of 41.64%. WPC made with bark fibers had better water resistance. Additionally, the composites reinforced with xylem fibers showed superior static bending strength, impact strength, and mildew-resistant properties as compared to the composites reinforced with bark fibers. WPC made from bamboo fibers exhibited the best water resistance, with a water absorption rate and thickness swelling rate of 1.83% and 1.42%, respectively. They also had the highest static bending strength, elastic modulus, and impact strength, at 41.31 MPa, 3.82 GPa, and 10.24 kJ/m2, respectively. The WPC made from fir xylem fibers showed the most effective mildew resistance, with the smallest damage (0.50).

Production and technical performance of scrimber composite manufactured from industrial low-value wood for structural applications

Development of scrimber composites and other engineered wood products from low-value wood and wood waste provides an effective opportunity to preserve natural resources, minimize waste, and innovate the production of higher-performance, environment-friendly construction materials. In this study, peeler cores, which are the center of poplar logs remaining after the peeling process in the veneer production, were utilized to develop scrimber composites. This study investigated the effects of different resins, including phenol-formaldehyde (PF) and urea formaldehyde (UF), as well as hydrothermal treatments at various temperatures (60 °C and 130 °C), on the physical and mechanical properties of the scrimber composites. Chemical changes in wood components and morphological changes in wood cell walls resulting from hydrothermal treatment were analyzed using Fourier transform infrared spectroscopy and scanning electron microscopy. To clarify how resin type and hydrothermal treatment affect structural performance, several physical and mechanical properties of scrimber composites, including thickness swelling, water absorption, internal bond strength, bending modulus of elasticity, and modulus of rupture, were measured. The test results revealed that hydrothermally treated wood scrims at 130 °C, when bonded with PF resin, produced scrimber composites with superior structural performance.

Theoretical and experimental studies on the bending properties of glued laminated timber manufactured with Chinese fir

China has been increasingly promoting the use of prefabricated timber structure buildings in recent years. However, unlike other countries, China lacks a diverse range of local tree species and engineered wood products suitable for load-bearing components in timber structures. This shortage poses a risk to the sustainable development of timber structures in China. This issue is addressed in this study, which focuses on the development and manufacture of glued laminated timber (GLT) using Chinese fir from plantation forests. The dynamic elastic modulus of 549 laminae was evaluated using the FAKOPP stress wave approach. A total of 28 laminae were randomly selected from Classes I, II, and III to assess the influence of stress grading on bending performance. This study included an analysis of failure modes, bending capacity, and the prediction model for bending stiffness of GLT with different layups and cross-sectional heights. The findings showed that the dynamic elastic modulus of the laminae followed a normal distribution. The bending strength and modulus of elasticity of finger-jointed laminae across different grades were 29.59 MPa to 37.05 MPa and 8.13 GPa to 10.94 GPa, respectively. The mechanical properties of both same-grade and mixed-grade composition GLT manufactured from Chinese fir met the TCT28 (MOR≥28 MPa, MOE≥8000 MPa) and TCYD24 (MOR ≥ 24 MPa, MOE ≥ 8000 MPa) garde requirements in GB/T26889, respectively. Failure modes in the GLT specimens typically began at the knots or finger joints of the bottom layer laminae. The cross-sectional height had no significant effect on the modulus of elasticity of GLT but exerted a significant effect on bending strength. The prediction model for bending stiffness, developed using the transformed section method, agreed with the experimental results. The outcome of this research provides a scientific and data-driven foundation for the application of Chinese fir in the field of structural materials.

Improving flexural performances of fused filament fabricated short carbon fiber reinforced polyamide composites with natural‐inspired structural design

AbstractBoth the nacre‐like bionic microstructure and the spiral laminated bionic configuration exhibit superior damage‐tolerance characteristics. On the basis of this observation, the design concept of the bionic helical‐interlayer configuration is innovatively integrated into the design of a bionic nacre‐like honeycomb structure. By systematically studying different spiral angles of honeycomb's interlayer stacking forms, their influence on the structural performance is deeply discussed with four‐point bending tests. Mechanical samples are carefully prepared using short carbon fiber reinforced polyamide composites (i.e., PA6‐CF) through conventional fused filament fabrication (FFF) 3D printing technology, where the accuracy and reliability of the designed bio‐inspired samples are ensured. The experimental results reveal significant improvements in bending strength and elastic modulus across various bionic nacre‐like honeycomb spiral structures compared to uniformly overlap configurations. In particular, the SH‐7.5 sample shows a remarkable 35.47% increase in bending strength and a 65.10% increase in elastic modulus over the SH‐11.25 sample. SEM‐based microstructural analyses are carried out to further explore the fracture mode of the carbon fibers, implied the helical configuration adopted in the nacre‐like honeycomb structure enhances the flexural resistant ability of the PA6‐CF composites. The findings above bear important guiding significance and reference value for the design of lightweight and high damage‐tolerance composite structures.Highlights A novel bio‐inspired structure is implemented to improve the mechanical performance of fused filament fabricated polyamide composites, where the bionic spiral helical configuration is integrated into high‐fracture‐resistance nacre‐like honeycomb structures. Mechanical testing results indicate that a helix angle under 10° results in a significant improvement in the structural performance of flexural strength. Microstructural analysis reveals that the helical configuration enhances the load‐bearing functionality of reinforcing carbon fibers in the printed polyamide composites. FFF 3D printing enables further implementation of the proposed bio‐inspired novel structure for lightweight and damage‐tolerant composite applications with high customization demands.

The effect of resin type on the properties of fibreboards coated with digilam decor papers used in interior design

The decorative paper industry is a highly competitive industrial sector. Manufacturers of impregnated paper for face-laminated medium-density fibreboard (MDF) and particleboard need to significantly reduce production costs to increase profit margins. Melamine formaldehyde resin (MF) formulations are a costly raw material widely used for impregnating and coating such papers. In this study, the effect of resin-impregnated digilam decor paper on the physical, mechanical and surface properties of MDF board was investigated using a new melamine-urea-formaldehyde resin formulation.100% melamine (MF), 100% urea formaldehyde (UF) and 50% MF + 50% UF resin were used in the impregnation process of the digilam decorative papers. In physical properties, the minimum water absorption and thickness swelling values after 24 hours of soaking in water are 21.93% and 1.81% in UF, 16.84% and 1.22% in MF, 13.79% and 1.22% in UF+MF, respectively. In mechanical properties, the values of bending strength and modulus of elasticity in bending were obtained as 32.14 and 3957.73 N/mm2, in UF, 40.39 and 6983.82 N/mm2 in MF, and 36.96 and 5290.06 N/mm2 in UF+MF, respectively. The results of simple statistical analysis of the data obtained from the surface tests have determined that the resistance values against staining, water vapor and scratching on the board scovered with digilam decorative papers produced using MF and UF + MF meet the limits required in the relevant standards. As a result, the boards covered with MF impregnated digilam decorative papers showed better performance than the boards coated with UF and UF+MF impregnated digilam decorative papers.

Chitosan hybrid nanomaterials: A study on interaction with biomimetic membranes

This study examined the influence of nanomaterials (NMs) on the organization of membrane lipids and the resulting morphological changes. The cell plasma membrane is heterogeneous, featuring specialized lipid domains in the liquid-ordered (Lo) phase surrounded by regions in the liquid-disordered (Ld) phase. We utilized model membranes composed of various lipids and lipid mixtures in different phase states to investigate the interactions between the NMs and membrane lipids. Specifically, we explored the interactions of pure chitosan (CS) and CS-modified nanocomposites (NCs) with ZnO, CuO, and SiO2 with four lipid mixtures: egg-phosphatidylcholine (EggPC), egg-sphingomyelin/cholesterol (EggSM/Chol), EggPC/Chol, and EggPC/EggSM/Chol, which represent the coexistence of Ld, Lo, and Ld/Lo, respectively. The data show that CS NMs increase the membrane lipid order at glycerol level probed by Laurdan spectroscopy. Additionally, the interaction of CS-based NMs with membranes leads to an increase in bending elasticity modulus, zeta potential, and vesicle size. The lipid order changes are most significant in the highly fluid Ld phase, followed by the Lo/Ld coexistence phase, and are less pronounced in the tightly packed Lo phase. CS NMs induced egg PC vesicle adhesion, fusion, and shrinking. In heterogeneous Lo/Ld membranes, inward invaginations and vesicle shrinking via the Ld phase were observed. These findings highlight mechanisms involved in CS NM-lipid interactions in membranes that mimic plasma membrane heterogeneity.

Novel kraft-lignin-based adhesives for the production of particleboards

Lignin is produced worldwide in pulp mills and is currently mainly used for energy recovery. Because of its chemical properties, one possible utilisation is the production of lignin-based materials. Currently, developed lignin-based adhesives are based mainly on lignosulfonate instead of kraft lignin since lignosulfonate is more reactive than kraft lignin. However, worldwide substantially more kraft lignin is produced. The presented research deals with the development of resin chemically modified with kraft lignin up to 40% (w/w) content of kraft lignin. The synthesis of adhesives is described, and developed adhesives are characterised. Namely, viscosity, mechanical properties of resins and results of differential scanning calorimetry are presented. Furthermore, the developed kraft-lignin-based adhesives were used for the production of particleboards. Pre-pressing in a cold press followed by hot pressing in a laboratory press was used for the production of particleboards. The physical (thickness swelling, moisture uptake, vertical density profile), as well as mechanical (internal bonding, modulus of rupture, modulus of elasticity in three-point bending) properties of particleboards, were evaluated. The results clearly show that kraft lignin can be used for the production of lignin-based adhesives for the production of particleboards.

A high-strength laminate made of small-diameter plantation wood: Flatwise bending mechanical properties

The aim of this study was to explore the feasibility of manufacturing high-strength laminates from small-diameter plantation wood. A Chinese fir (Cunninghamia lanceolata) plantation comprising trees with a diameter at breast height of less than 30 cm was selected as the material in this study. The flatwise bending mechanical properties of the Chinese fir laminates with both non-finger-jointed (NFJ) and finger-jointed (FJ) were investigated. The results indicated that finger jointing did not affect the bending elastic modulus (MOE) of the laminates, but it could reduce the bending strength index and the coefficient of variation of the bending strength (MOR). Notably, an optimal correlation existed between the MOE and MOR for both NFJ and FJ laminates, indicating that the MOE could serve as the dominant control variable for the machine grading of laminates. The failure mode significantly influenced the bending mechanical properties of both the NFJ and FJ laminates, whose dominant failure modes were fiber failure near the knot and whole fractures of the finger jointing teeth roots, respectively. For both the NFJ and FJ laminates, the overall macroscopic morphology of the high-strength specimen was relatively flat, but the microscopic morphology was uneven owing to fiber pull out, while the low-strength specimen was the opposite. Compared to the traditional visual grading method, the proposed machine grading method could more scientifically and effectively identify the quality, reduce the coefficient of variation of the bending mechanical properties, and significantly improve the strength index of laminates. This study provides basic support for manufacturing high-strength laminates from small-diameter plantation wood.

Incipient decay in beech (Fagus sylvatica L.) and linden (Tilia cordata Mill.): An interspecific static and dynamic material analysis

With increasing awareness of the ecological value of trees in urban areas, there is a growing need to preserve mature specimens often colonised by wood-decay fungi. Nonetheless, cases of stem collapse or uprooting of such trees under adverse weather conditions remain a significant issue requiring further investigation. Depending on the decay type and the wood structure of the host tree, different combinations of wood-decaying fungi and host species can have varying impacts on the mechanical and vibroacoustic properties of green wood. This study compares the physical and mechanical properties of green European beech (Fagus sylvatica L.) and small-leaved linden (Tilia cordata Mill.) artificially exposed to Fomes fomentarius (L.) Fr. and Kretzschmaria deusta (Hoff.) P.M.D. Martin after different exposure periods. Mass loss (ML) caused by both fungi differed according to the wood species. A statistically significant difference between the two fungal species was observed in beech wood, but not in linden. Significant differences in the modulus of rupture (MOR) and dynamic bending modulus of elasticity (MOED) were observed among the fungus-wood combinations, also depending on the exposure time. The relationships between ML and MOR varied according to the fungal species, where at the same ML values, K. deusta caused a higher MOR loss in both wood species. Strong relationships between MOED and MOR were demonstrated for all fungus-wood combinations, without significant differences related to the decay type. The MOED is a reliable parameter for predicting MOR loss even at incipient degradation stages, irrespective of the type of decay. The presented results can lead to better prediction of the impact of fungal colonization on standing trees and improve non-destructive methods used for tree stability assessment.

Study on the Shear and Bending Mechanical Properties of Millet Stem

To determine the patterns and influencing factors of the mechanical properties of millet stems from different varieties during the maturity period, this study employed a complete block experiment method and conducted shearing and bending tests on millet stems using the INSTRON5544 electronic universal material testing machine. The research investigated the variation in the shear strength, specific shear energy, bending strength, elastic modulus, and bending stiffness at different internode positions of the stems of Changza 466, Zhangza 16, and Jingu 21 during their maturity period. The results indicated that the variety had a significant impact on the mechanical properties of millet stems: from largest to smallest, the order of shear and bending forces was Jingu 21, Zhangza 16, and Changza 466. The shear strength and bending strength of Jingu 21 were the greatest among the three stem samples. The internode position significantly affected the shear mechanical properties of the millet stems, showing a general trend of decreasing shear strength with ascending internode position. The effect of the internode position on the bending stiffness was highly significant, whereas its impact on the bending strength and elastic modulus was not significant. The shear strength of the millet stems ranged from 3.866 ± 1.086 to 6.953 ± 2.208 MPa, significantly lower than the bending strength, which ranged from 18.934 ± 4.374 to 34.286 ± 6.875 MPa. The lowest shear strength and specific shearing energy, recorded at the fifth internode, were 4.028 ± 1.918 MPa and 15.097 ± 12.633 MJ/mm2, respectively. Jingu 21 and Changza 466 exhibit better lodging resistance than Zhangza 16. It is recommended to use a cutting-type platform for harvesting millet stems, with the cutting height set at the fifth internode position. This study provides a theoretical basis for the design of millet harvesting machinery and the selection of harvest parameters.

Evaluation of Timber Degradation Caused by Insects to Quantify the Mechanical Strength of Load-Bearing Elements

ABSTRACT Timber elements within historic structures are often susceptible to biological decay caused by insects. The areas affected by insect attacks are typically not considered in the structural analysis, although they may still provide some strength. Hence, accurately assessing the extent and intensity of insect damage is crucial for determining the actual strength of timber members. The present work presents the results obtained on insect-damaged timber members that were evaluated based on the proportion of the surface area occupied by bore holes, a method that is readily applicable by skilled operators during on-site inspections. Resistance to penetration (by drilling) and standard mechanical tests were then carried out to measure density in addition to strength (compression, shear, bending) and modulus of elasticity in bending. The results evidenced moderate yet highly significant inverse correlations between degree of degradation and mechanical properties. In contrast, density showed no discernible correlation with the degree of decay, nor did penetration resistance. However, drilling resistance showed a robust correlation with density and mechanical characteristics. The coupling between visual assessment of decay and evaluation of resistance to penetration allowed accurate prediction of mechanical properties similar to healthy wood.

Biomechanical Properties of Novel Porous Scaffold Core and Hollow Lateral Hole Pedicle Screws: A Comparative Study in Bama Pigs.

Screw loosening is a common complication of internal fixation of pedicle screw. Therefore, the development of a pedicle screw with low loosening rate and high biosafety is of great clinical significance. This study aimed to investigate whether the application of a porous scaffold structure can improve the stability of pedicle screws by comparing the biomechanical properties of novel porous scaffold core pedicle screws (PSCPSs) with those of hollow lateral hole pedicle screws (HLHPSs) in a porcine lumbar spine. Thirty-two pedicle screws of both types were implanted bilaterally into the L1-4 vertebrae of four Bama pigs, with our newly designed PSCPSs on the right and HLHPSs on the left. All the Bama pigs were sacrificed 16 weeks postoperatively, and the lumbar spine was freed into individual vertebrae. Biomechanical properties of both the pedicle screws were evaluated using pull-out tests, as well as cyclic bending and pull-out tests, while the mechanical properties were assessed using three-point bending tests. The data generated were statistically analyzed using paired-sample t-tests and two independent sample t-tests. We found that the maximal pull-out forces before and after cyclic bending of the PSCPSs (1161.50 ± 337.98 N and 1075.25 ± 223.33 N) were significantly higher than those of the HLHPSs (948.38 ± 194.32 N and 807.13 ± 242.75 N) (p < 0.05, p < 0.05). In 800 cycles of the bending tests, neither PSCPS nor HLHPS showed loosening or visible detachment, but their maximal pull-out forces after cyclic bending tests decreased compared to those in cycles without cyclic bending tests (7.43% and 14.89%, respectively), with no statistical significance (p > 0.05 and p > 0.05, respectively). Additionally, both screws buckled rather than broke in the three-point bending tests, with no statistically significant differences between the maximal bending load and modulus of elasticity of the two screws (p > 0.05 and p > 0.05, respectively). Compared with the HLHPSs, the PSCPSs have greater pull-out resistance and better fatigue tolerance with appropriate mechanical properties. Therefore, PSCPSs theoretically have significant potential for clinical applications in reducing the incidence of loosening after pedicle screw implantation.

Characterization of fly ash reinforced wood polypropylene composites

In this study, fly ash, which is released as waste from thermal power plants and has negative effects on the environment, was evaluated as a filler in wood-plastic composite materials (WPC). For this purpose, inorganic fly ash from thermal power plants was mixed with polypropylene (PP) thermoplastic polymer at 10%, 20%, 30%, 40%, and 50% by extrusion method instead of wood flour used in wood plastic composite materials. Maleic anhydride-treated polypropylene (MAPP) was used to strengthen the bonding during WPC production. The material mixed in extrusion was passed through a crusher and turned into pellets. Test samples were prepared using injection molding of pelletized WPC material. Density, thickness swelling, water absorption, modulus of rupture, impact strength, modulus of elasticity in bending, tensile strength, janka hardness, differential scanning calorimetry (DSC), and thermogravimetric analyses (TGA) were performed on the prepared test samples. The results indicated that as the amount of fly ash used in the wood-plastic composite material increases, the density increases but the thermal degradation temperature of the material, water uptake, the swelling ratio to its thickness, tensile strength, impact strength, janka hardness, modulus of rupture, and modulus of elasticity decrease.

Gradient Variation and Correlation Analysis of Physical and Mechanical Properties of Moso Bamboo (Phyllostachys edulis).

This study aimed to investigate the gradient properties of bamboo at the microscopic level and provide a basis for improving the utilization rate of bamboo. Using moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) as a research subject, the variation of vascular bundle area percentage, chemical content, relative crystallinity (CR), mechanical properties of different bamboo slivers, and correlation between those parameters were analyzed. From the bamboo green layer (BGL) to the bamboo yellow layer (BYL), the distribution of vascular bundles changed from dense to sparse. Cellulose and lignin mass content decreased gently, and hemicellulose mass content showed gradual increases. The CR showed an order of bamboo middle layer (BML) > BGL > BYL. The tensile modulus of elasticity, tensile strength, bending modulus of elasticity, and bending strength decreased from BGL to BYL. The order of influence degree on mechanical properties of moso bamboo was vascular bundle area, hemicellulose content, lignin mass content, density, and CR, and these factors correlated with mechanical properties at a significant level (p < 0.05). Vascular bundle area had a decisive effect on the mechanical properties of bamboo. The vascular bundle area and density were linearly correlated with mechanical properties, while the lignin mass content and CR were curve-linearly correlated with mechanical properties.

INFLUENCE OF SITES ON THE PHYSICAL AND MECHANICAL PROPERTIES OF NATIVE TROPICAL WOODS

The Amazon rainforest displays wide ecological diversity, reflected in its wood variation. The study evaluated the influence of different locations on the properties of wood from native tropical species extracted from the Brazilian Amazon. The most frequent species in the locations were selected, and a total of 104 trees were extracted. The logs were sawed breakdown to make beams (50 × 110 × 2,000 mm). The wood density and mechanical resistance of these samples were determined. The wood density ranged of 0.25-1.00 g/cm3, modulus of elasticity and rupture in static bending ranged of 5,982-19,025 MPa and 35-204 MPa, respectively. For compressive strength parallel to the grain, the range was 24-111 MPa; the strength of wood compressed parallel was 20-245 MPa, and the shear strength was 50-245 MPa. The study detected differences in the physical and mechanical properties of the woods regarding the origin of the sites (Amazonas-Pará/Brazil), with the modulus of elasticity and the wood density showing the greatest variations.

Effects of three different powder pre-processing and two-step sintering processes on the microstructure and mechanical properties of Cu–Sn–Ti porous matrix materials

It is difficulty to utilize the pore formation function of TiH2 in the copper-based matrices of diamond tools due to the mismatch between dehydrogenation temperature and densification temperature. In this study, Cu–Sn–Ti porous materials were prepared by innovative powder pre-processing and two-step sintering processes. The results showed that Cu–Sn–TiH2 powder with uniform composition, high alloying degree and high TiH2 retention rate were achieved by optimizing pre-processing parameters. During the subsequent sintering process, Sn and Ti elements were precipitated from the copper matrix, leading to the formation of Ti-rich phases at grain boundaries and pore walls. Simultaneously, pores with higher sphericity and uniform distribution were formed due to the thermal decomposition of TiH2. The porosity, average pore size, bending strength, and bending elastic modulus of Cu–Sn–Ti porous material were measured as 30.6%, 2.15 μm, 245 MPa, and 2.23 GPa, respectively. The comprehensive properties were better than the reported results.