Dimensional Stability Research Articles

ASSESSING THE IMPACT OF ENGINEERED WOOD PRODUCTS ON SUSTAINABLE CONSTRUCTION: A COMPARATIVE STUDY WITH CONVENTIONAL CONCRETE BUILDING METHODS

Renewable-sourced EWPs offer enhanced dimensional stability, durability, and mechanical properties, facilitating larger and more complex structural elements, and contributing to faster construction times and better energy performance. The research investigates the feasibility and effectiveness of Engineered Wood Products (EWPs) as sustainable building materials in the construction sector by a comparison of their cost, performance, and environmental impact against conventional concrete. The research emphasises the importance of innovative design, recycling, and waste reduction in fostering sustainable construction methods that satisfy the demands of present and future generations while conserving energy. However, there are negative environmental impacts linked to the production of concrete, such as habitat destruction, atmospheric emissions, and waste generation. The research adopted a web-based survey to gather quantitative data from construction experts. The Relative Importance Index (RII) was adopted to analyze the respondents' perceptions of the benefits of EWP and concrete negative effects. The results of the research reflect respondents' significant preference for EWPs and are consistent with their outstanding environmental qualities. In conclusion, this paper argues that EWPs possess the potential to effectively revolutionise the construction industry by minimising its carbon footprint and encouraging sustainable construction practices that are required for addressing the expectations of both the present and the future.

Programmable, Self-Healable, and Photochromic Liquid Crystal Elastomers Based on Dynamic Hindered Urea Bonds for Biomimetic Flowers.

Recently, researchers have been exploring the use of dynamic covalent bonds (DCBs) in the construction of exchangeable liquid crystal elastomers (LCEs) for biomimetic actuators and devices. However, a significant challenge remains in achieving LCEs with both excellent dynamic properties and superior mechanical strength and stability. In this study, a diacrylate-functionalized monomer containing dynamic hindered urea bonds (DA-HUB) is employed to prepare exchangeable LCEs through a self-catalytic Michael addition reaction. By incorporating DA-HUB, the LCE system benefits from DCBs and hydrogen bonding, leading to materials with high mechanical strength and a range of dynamic properties such as programmability, self-healing, and recyclability. Leveraging these characteristics, bilayer LCE actuators with controlled reversible thermal deformation and outstanding dimensional stability are successfully fabricated using a simple welding method. Moreover, a biomimetic triangular plum, inspired by the blooming of flowers, is created to showcase reversible color and shape changes triggered by light and heat. This innovative approach opens new possibilities for the development of biomimetic and smart actuators and devices with multiple functionalities.

3D Printed P(VdF‐HFP)/SBA‐15 composite‐based gel polymer electrolyte versus commercial celgard: A comparative investigation on thermal stability and electrochemical performance for lithium‐ion battery application

AbstractThe current work reports on tailoring of 3D printed gel polymer electrolyte (GPE) employing poly(vinylidene fluoride‐co‐hexafluoropropylene) P(VdF‐HFP) as the host matrix and mesoporous Santa Barbara Amorphous‐15 (SBA‐15) mesoporous sieve as ceramic filler. Further, this work envisages an investigation on its physicochemical properties, thermal shrinkage behavior, and electrochemical performance. An effort has been undertaken to formulate 3D printable P(VdF‐HFP)/SBA‐15 composite‐based GPE ink with suitable rheological properties. The breath figure method is followed to investigate the influence of 1‐methyl‐2‐pyrrolidinone (NMP)/tetrahydrofuran (THF) mixture as a solvent on the porosity of 3D printed GPE, through which enhanced porosity is evident from scanning electron microscopy (SEM) analysis. The morphological analysis further confirms the hybrid porous structure facilitated by the addition of SBA‐15 into the P(VdF‐HFP) matrix. The 3D printed P(VdF‐HFP)/SBA‐15 (10%) composite‐based GPE shows promising ionic conductivity in the order of 0.2 × 10−4 S/cm at room temperature and demonstrates excellent dimensional thermal stability up to 175°C. The electrochemical measurement of 3D printed GPE is tested separately using 3D printed cathode half‐cell (3D printed LFP vs. Li+) and 3D printed anode half cell (3D printed LTO vs. Li+) with GPE as separator. Further, also tested with conventionally prepared electrode and the coin cell studies show discharge capacity of 3D printed P(VdF‐HFP)/SBA‐15 (10%) composite‐based GPE is comparable to commercial celgard separator. All these features speculate that the 3D printed fabricated in the current work may find potential application in lithium‐ion battery.

Dynamics and Internal Structure Evolution during the Glass Transition of the Ethylene-Cyclic Olefin Copolymers: A Molecular Dynamics Simulation.

Amorphous ethylene-cyclic olefin copolymers (COCs) which can be used in cell phone lenses and prefilled syringes have attracted increasing attention due to their excellent and tunable thermal properties. In order to better explain the influence of COC microstructure (cyclic olefin types and content) on the glass transition mechanism, we used molecular dynamics (MD) simulations to track the evolution of free volume, diffusion coefficients, atomic mobility, trans conformation probabilities, and characteristic parameters of α-relaxation kinetics during the quenching process. MD results show that for the classic COC E-co-NB (ethylene-norbornene copolymer), an increase in cyclic olefin content from 25 to 50 mol % reduces atomic mobility, limiting the molecular chain movement at higher temperatures and improving Tg. Compared to NB, the more rigid rings in tricyclopentadiene (TCPD) and exo-1,4,4a,9,9a,10-hexahydro-9,10(1',2')-bridged phenylidene-1,4-bridged methylideneanthracene (HBM) have the following effects: (1) reducing the thermal expansion coefficient and overall chain mobility; (2) enhancing the diffusion energy barrier; (3) promoting the formation of local ordered structures; (4) accelerating α-relaxation dynamics at high temperatures and improving the dynamic fragility m. These lead to an upward shift in the temperature region where chain movement is limited and thus improve Tg and high-temperature dimensional stability. In this simulation, the correlation equation between Tg, m, and the microstructural parameters of COCs is established, which is of great significance for the development of COCs with high performance.

Study on the characteristics of glass fiber‐reinforced polymers from recycled wind turbine blades as reinforcement in particleboard

AbstractGlass fiber‐reinforced polymer (GFRP), extensively employed in diverse industries, generates considerable waste, especially from decommissioned wind turbine blades. Our research group has developed a new method of mechanical recovery for GFRP from wind turbine blades. In this study, waste GFRP was processed into a mixed particle size of 0.9–6 mm using a crusher and a screening machine, and then added as reinforcement materials to particleboards. The effects of different levels of four factors (GFRP addition, hot pressing temperature, hot pressing time, and binder dosage) on the properties of GFRP particleboards were evaluated by orthogonal experiments. The study results showed that the particleboards with 30 wt% GFRP improved modulus of rupture (MOR), modulus of elasticity (MOE), and internal bonding strength (IB) by 74.94%, 42.28%, and 92.05%, respectively, compared to pure poplar particleboards. Moreover, GFRP particleboards demonstrated better water resistance and dimensional stability than commercial particleboards and excelled in thermal stability. Recycling GFRP waste from decommissioned wind turbine blades and incorporating it into particleboard production can reduce environmental pollution, increase the resource recovery utilization rate, and contribute to sustainable manufacturing practices.Highlights Low‐cost and efficient methods of recycling wind turbine blades were proposed. Recycled GFRP from wind turbine blades can be used as reinforcement for particleboard. The prepared particleboards have excellent physical and mechanical properties and are thermally stable. Determination of the optimal glass fiber‐reinforced polymer addition level in particleboard at 30 wt%.

Enhancing water resistance and flame retardancy of wood through phytic acid catalyzed in-situ polyesterification

The treatment of wood using in-situ polyesterification with citric acid and D-sorbitol (SCA) is a novel method for enhancing wood properties. This method can effectively improve the dimensional stability and biological durability of wood. However, achieving effective fixation of polyester in wood at lower curing temperatures has not been achieved. In this study, phytic acid was used to catalyze in-situ polyesterification of SCA. The autocatalytic reaction pattern of SCA polyesterification was elucidated through an investigation of the kinetics of the curing reaction. It was also confirmed that phytic acid reduces the curing temperature and activation energy of SCA. The investigation of polyesters revealed that phytic acid catalysis enhances the esterification degree and thermal stability of the polyester. Wood treated with SCA and 2%wt phytic acid exhibited a 44% reduction in polyester leaching. Moreover, it demonstrated high water resistance and dimensional stability, with water repellency efficiency of up to 33.8% and anti-swelling efficiency of up to 46.2%. Remarkably, it exhibited excellent flame retardancy, with an oxygen index of 33.1% and a 47.5% reduction in total heat release. The outstanding flame retardancy is attributed to the dual action of phytic acid in both the solid phase and gas phase.

Oxygenated moiety enhanced thermal stabilization, mechanical, and thermomechanical performance of polyacrylonitrile/single wall carbon nanotubes films

AbstractThermo‐oxidative stabilization of polyacrylonitrile (PAN)‐copolymer and PAN/single‐walled carbon nanotube (SWCNT) composite films were studied in the presence of oxygenated entities which may act as an internal oxygen supplier. The oxygenated moiety exhibited dual behavior, enhancing the stabilization efficiency of PAN while also improving the dispersion of SWCNT. The addition of oxygenated moiety treated SWCNT to PAN resulted in a significant reduction in activation energy from 118 kJ/mol to 99 kJ/mol, owing to a more stable oxidation reaction. Thermogravimetric analysis showed weight loss due to stabilization, and polymer chain degradation was lower in treated SWCNT composite films, resulting in an approximate 6% increase in residual weight. Mechanical testing showed a significant increase in tensile strength to 54.15 MPa and tensile modulus to 2.53 GPa with elongation at break of 13.2%, which is attributed to the enhanced interfacial shear strength resulting from the improved dispersion of oxygenated moiety‐treated nanotubes. Furthermore, thermomechanical analysis studies showed improvement in dimension stability with oxygenated moiety treated SWCNT composite films, attributed to better dispersion and increased interfacial strength between the polymer and filler.Highlights Oxygenated entities stabilize PAN and improve SWCNT dispersion. Activation energy was reduced from 118 to 99 kJ/mol with Tween‐80. Residual weight increased by 6% with treated SWCNT in TGA. Improved tensile strength (54.14 MPa), modulus (2.53 GPa) with modified SWCNT. Dimension stability is enhanced by interfacial strength with modified SWCNT.

MMT‐St and PLA synergistically enhanced the microcellular of TPU foam and improved its dimensional stability

Thermoplastic polyurethane elastomer (TPU) is a commonly used material for foam preparation. However, its application is hindered by significant shrinkage behavior. To reduce the foam shrinkage, polylactic acid (PLA) and calcium stearate‐modified montmorillonite (MMT‐St) were incorporated into the polyurethane matrix. The TPU/PLA/MMT‐St composite foams were formed using an intermittent supercritical carbon dioxide (scCO2) foaming process. The addition of PLA inhibited the relaxation of TPU chain segments, while the introduction of calcium stearate (GaSt2) improved the dispersion of MMT within the matrix, increased the nucleation sites of cell growth, and improved cell structure. The cell diameter decreased from 10 to 4 μm, while the cell density increased from 4.1×1012 to 15.8×1012 cell/cm3. In addition, the cell distribution range narrowed from 4‐19 to 2‐6 μm. Incorporating MMT‐St increased the crystallinity and thermal stability of TPU/PLA, mitigated chain relaxation at room temperature, and enhanced foam dimensional stability. As a result, this led to a decrease in shrinkage rate from 27.5 to 5%. As both matrices of the material are thermoplastic, this composite foam possesses recyclability with enhanced material utilization.This article is protected by copyright. All rights reserved.

The impact of base design and restoration type on the resin consumption, trueness, and dimensional stability of dental casts additively manufactured from liquid crystal display 3D printers.

To evaluate the effects of two base types and three restoration designs on the resin consumption and trueness of the 3D-printed dental casts. Additionally, the study explored the dimensional stability of these 3D-printed dental casts after 1 year of storage. Various types of reference dental casts were specifically designed to represent three types of dental restoration fabrications, including full-arch (FA), long-span (LS), and single-unit (SU) prostheses. The reference casts were digitized with a dental laboratory scanner and used to create flat and hollow base designs (N = 18) for the 3D-printed study casts. The 3D-printed study casts were digitized and evaluated against their corresponding references immediately after 3D printing and again after 1 year of storage, with the trueness quantified using the root mean square error (RMSE) at both time points. Volumes of resin used were recorded to measure resin consumption, and the weights of the 3D-printed study casts were also measured. The data were analyzed using two-way ANOVA and a Tukey post hoc test, α = 0.05. Volumetric analysis showed the flat-base design had significantly higher resin consumption with weights for the FA group at 42.51 ± 0.16g, the LS group at 31.64 ± 0.07g, and the SU group at 27.67 ± 0.31g, as opposed to 26.22 ± 1.01g, 22.86± 0.93g, and 20.10 ± 0.19g for the hollow designs respectively (p < 0.001). Trueness, assessed through two-way ANOVA, revealed that the flat-base design had lower RMSE values indicating better trueness in the LS (54 ± 6 µm) and SU (59 ± 7 µm) groups compared to the hollow-base design (LS: 73 ± 5, SU: 99 ± 11 µm, both p < 0.001), with no significant difference in the FA group (flat-base: 50 ± 3, hollow: 47 ± 5 µm, p= 0.398). After 1 year, the flat-base design demonstrated superior dimensional stability in the LS (flat base: 56 ± 6 µm, hollow base: 149 ±45 µm, p < 0.001) and SU groups (flat base: 95 ± 8 µm, hollow base: 183 ±27 µm, p < 0.001), with the FA group showing no significant difference in the base design (flat base: 47 ± 9, hollow base: 62 ± 12 µm, p = 0.428). The hollow-base design group showed lower resin consumption than the flat-base design group. However, the flat-base designs exhibited superior trueness and less distortion after 1 year of storage. These findings indicate that despite the higher material usage, flat-base designs provide better initial accuracy and maintain their dimensional stability over time for most groups.

Recycling of mineral wool waste as supplementary cementitious material through thermochemical treatment.

Mineral wool is commonly used in construction as thermal insulation material. After the product's lifetime, it is classified as hazardous waste if no trademark of the European Certification Board for Mineral Wool Products (EUCEB) or the German Institute for Quality Assurance and Labelling (RAL) exists. Mineral Wool Waste (MWW) is typically landfilled in Europe, which is challenging due to its low bulk density and dimensional stability. This circumstance highlights the need for alternative recycling methods that increase the recycling rate of construction and demolition (C&D) waste. This article outlines the recycling opportunities of MWW and focuses on the use of thermochemical treatment of different mixtures of input materials to produce a supplementary cementitious material (SCM). The material characterisation results and investigations on the binder suitability demonstrate that the slag fractions after the thermochemical treatment are well-qualified to be used as reactive binder components. Additionally, a material flow analysis was conducted to estimate the substitution potential of MWW as SCM in the Austrian cement industry.

Remarkable impact of chain backbone on the performance of Poly(norbornene derivatives)-based anion exchange membranes

Chemical stability and the trade-off between ion conductivity and dimensional stability are two primary challenges for the development of suitable anion exchange membranes (AEMs). Herein, a series of non-crosslinked poly(norbornene derivatives)-based AEMs containing a bulky steric hindrance hydrophobic arylene substituent were prepared by vinyl addition polymerization (VAP), ring-opening metathesis polymerization (ROMP), and ROMP followed post-hydrogenation, respectively. Compared with ROMP and hydrogenated type membranes, VAP-type membranes, especially the VAP-N-50, exhibited excellent dimensional stability with limited swelling ratio (SR = 27.9 %) while higher water uptake (WU = 213.8 %) at 80 °C, which is attributed to its rigid VAP-type cyclic chain backbone. Microtopography study demonstrated the existence of nanoscale phase separation in VAP-type AEMs and its association with water uptake and swelling behavior. VAP-N-60 showed excellent hydroxide conductivity up to 105.5 mS cm−1 at 80 °C, while exhibited superior alkaline stability that was not found in ROMP-type membrane ROMP-N-50 and the hydrogenated-type membrane H-ROMP-N-50. After being immersed in 2 M NaOH solution at 80 °C for 1200 h, the hydroxide conductivity loss of VAP-N-60 was only 3.0 %. Furthermore, a H2/O2 single cell using VAP-N-50 membrane achieved the highest peak power density of 722 mW cm−2 at 60 °C without back pressure.

Dimensional Stability of Additively Manufactured Dentate Maxillary Diagnostic Casts in Biobased Model Resin.

This study aimed to evaluate the dimensional stability of maxillary diagnostic casts fabricated from a biobased model resin, which consists of 50% renewable raw materials for sustainable production, a model resin, and stone, over one month. A master maxillary stone cast was digitized with a laboratory scanner to generate a reference file. This master cast was also scanned with an intraoral scanner to additively manufacture casts with a biobased model resin (BAM) and a model resin (AM). Polyvinylsiloxane impressions of the master cast were also made and poured in type III stone (CV) (n = 8). The same laboratory scanner was used to digitize each model one day (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4) after fabrication. Deviations from the reference file were calculated with an analysis software and analyzed with generalized linear model analysis (α = 0.05). The interaction between the material and the time point affected measured deviations (p < 0.001). Regardless of the time point, CV had the lowest and AM had the highest deviations (p < 0.001). BAM mostly had lower deviations at T0 and mostly had higher deviations at T4 (p ≤ 0.011). AM had the highest deviations at T4 and then at T3, whereas it had the lowest deviations at T0 (p ≤ 0.002). The measured deviations of CV increased after each time point (p < 0.001). BAM casts had deviations within the previously reported clinically acceptable thresholds over one month and had acceptable dimensional stability. Therefore, tested biobased resin may be a viable alternative for the sustainable manufacturing of maxillary diagnostic casts that are to be used clinically.

High-temperature dimensional stability and radiation behavior of high-entropy rare earth tungstate ceramics

Materials with high-temperature dimensional stability and resistance to radiation damage are receiving increasing attention in advanced nuclear energy systems. In this research, (Sm0.2Eu0.2Gd0.2Dy0.2A0.2)2W3O12-type (A = Y, Tm ,Ho) high-entropy ceramics is presented. The coefficients of thermal expansion of (Sm0.2Eu0.2Gd0.2Dy0.2Y0.2)2W3O12 (HE-RE2W3O12) is 7.21×10-6K-1 at 300-1100K, which is the lowest among the three synthesized high-entropy ceramics and indicates good dimensional stability at high temperatures. After irradiation with Kr+ fluence of 4.58×1016 ions/cm2 at 400oC, both HE-RE2W3O12 and Gd2W3O12 maintained crystalline, but the lattice volume expansion rate of HE-RE2W3O12 (0.71%) is much lower than that of Gd2W3O12 (1.49%). Additionally, in the post-irradiated HE-RE2W3O12, the Raman spectra vibration peak remained unchanged and no radiation-induced segregation was observed. Nanoindentation tests displayed that the degradation of hardness and elastic modulus in HE-RE2W3O12 is rarely degrade. Overall, these results provide new insights for research on advanced nuclear materials in the future.

Simultaneously enhanced the sound absorption coefficient and dimensional stability of Carboxymethyl cellulose/Clay Aerogel by impregnating polyurethane

Simultaneously enhanced the sound absorption coefficient and dimensional stability of Carboxymethyl cellulose/Clay Aerogel by impregnating polyurethane

Silk fibroin incorporated electrospun aliphatic polyester nanofiber scaffolds with excellent dimensional stability and cytocompatibility

Poly (lactide-co-glycolide) (PLGA) has been extensively utilized to fabricate electrospun fibers for tissue engineering scaffolds due to its good biocompatibility and biodegradability. However, such scaffolds in biological media shrink and distort severely, which is undesired for practical application. In this study, a silk fibroin incorporated electrospun aliphatic polyester nanofiber scaffold (PLGA/PCL/SF) was developed via facile one-step electrospinning, with PLGA as the substrate and incorporating polycaprolactone (PCL) and silk fibroin (SF). The resulting scaffold exhibited fine fibers and water absorbency. Particularly, the addition of SF into scaffolds improved the water adsorption ability, and that of PCL effectively prevented scaffold shrinkage behaviors. In vitro degradation analyses showed that it was accelerating for the obtained scaffolds with SF added, without any undesirable acidic environment induced. Additionally, the PLGA/PCL/SF scaffold exhibited the most promising result in cell proliferation, presenting a valuable insight into the design of tissue engineering scaffolds.

The metamaterial with high thermal-mechanical stability and the practical application as the microwave antenna: mechanical designs, theoretical predictions, and experimental demonstrations

To address the demand of maintaining the structural configuration upon extreme temperature changes, metamaterials with high thermal-mechanical stability have attracted wide attention recently. However, there are still some challenges for previous studies regarding mechanical design and practical application exploration. This manuscript proposes the design strategy for the lattice sandwich metamaterial with excellent zero thermal-induced warping, along with the metamaterial-based antenna with a high stability of electromagnetic signal transmission. Through the design strategy of discrete lattice units of the metamaterial, the ultra-low thermal warping of the metamaterial is realized upon the non-uniform temperature field. Here, the theoretical model is established to predict both heat transfer and thermal-induced deformation behavior upon complex mechanical-thermal loading conditions. The combination of theoretical predictions, finite element analysis, and experiments verifies the thermal dimensional stability of the metamaterial proposed here. Compared with the heterogeneous bilayer plate, experimental thermal warping of the metamaterial specimen is reduced by 99.7%. Additionally, compared with the bilayer-based specimen, gain attenuation, the main lobe's offset angle, and the voltage standing wave ratio offset of the metamaterial-based antenna specimen are experimentally reduced by 99.5%, 99.9% and 74.2%, revealing the huge application potential of this metamaterial in the field of spacecraft communication.

Enhanced interfacial, mechanical, and anti-hygrothermal properties of carbon fiber/cyanate ester composites with the catalytic sizing agents of titanium epoxy

The mechanical properties of composites are closely related to the interfacial behavior, especially under the hygrothermal circumstance. A catalytic sizing agent of titanium epoxy is designed to enhance interfacial, mechanical, and anti-hygrothermal properties of high modulus carbon fiber (HMCF)/cyanate ester composites simultaneously. The mechanisms of interface enhancement and low hygroscopicity of composites are investigated. The titanium epoxy is synthesized and its catalytic effect on the curing of cyanate ester is proved. The interfacial properties of HMCF composites with catalytic sizing agents are improved to 95.5 MPa, which is attributed to the interphase with high crosslinking density and sufficient triazine rings and oxazolidinone structure due to preferential curing induced by interfacial catalysis, stimulating the smooth transition of interphase modulus. Further, the formed interphase exhibits few interface defects and low content of hydroxyl groups, which changes the moisture diffusion path and reduces saturated water absorption of composites to only 0.36%, resulting in the release of interfacial wet stress concentration and high retention of mechanical properties in hygrothermal environment. The resultant composites with high stiffness, excellent temperature resistance, superior dimensional stability and low moisture absorption are expected to be applied to high-orbit space, aerospace, precision instruments.

Epoxy resin-based root canal sealers: An integrative literature review.

The correct obturation of the root canal system achieved by means of a core and a cement is essential for the success of endodontic treatment. There are several root canal cements (RCCs) on the market; however, because of their excellent characteristics, epoxy resin-based sealers (ERBSs) have been widely used. The main aim of this review was to analyze and integrate the available information on different ERBSs. An electronic search was performed in the PubMed and Scopus databases, using "epoxy resin" AND "root canal treatment", and "epoxy resin" AND "endodontics" as search terms. In general, ERBSs have good flow properties, film thickness, solubility, dimensional stability, sealing capacity, and radiopacity. They are also able to adhere to dentin while exhibiting low toxicity and some antibacterial effects. However, their main disadvantage is the lack of bioactivity and biomineralization capability. A large number of ERBSs are available on the market, and AH Plus keeps being the gold standard RCC. Yet, information on many of them is limited or non-existent, which could be due to the fact that some of them are relatively new. The latter emphasizes the need for relevant research on the physicochemical and biological properties of some ERBSs, with the aim of supporting their clinical use with sufficient evidence via prospective and long-term studies.

Hybrid coaxial 3D printing with nested-screw mechanism: Optimizing material integration and structural performance for coaxial designs

The emergence of multi-material extrusion systems has opened up new possibilities for 3D printing, spurring research on the combination of diverse materials and structures to enhance part quality and performance. In this work, a nested-screw coaxial co-extrusion 3D printing mechanism was designed for hybrid coaxial structures to address the viscosity matching limitation that is present in traditional coaxial extrusion. The high-viscosity shell material, with 3 wt% added carbon fiber, can be extruded and printed at room temperature. This suggests that the nested-screw can be used to adjust the high viscosity difference between the core and shell materials for co-extrusion. A model for coaxial extrusion was developed to establish appropriate printing parameters for the hybrid integration of materials and structures in coaxial designs. The resulting model for determining the printing parameters of the C-S structure improves dimensional stability and print repeatability. The coaxial printing was also employed to validate the bionic coaxial structure of antlers. The influence of the core-shell material and structure combinations on strength and toughness was thoroughly examined, enabling the optimization of structures with superior strength-toughness combinations. The comparative truss structure tests demonstrated that the core-shell structure enhanced damage absorption by 30.1 % compared to a single-structure design. This confirms the adjustability of mechanical properties in printed systems through a combination of hybrid materials and structure.

The Effect of Wet and Dry Cycles on the Strength and the Surface Characteristics of Coromandel Lacquer Coatings

Research on the degradation mechanism of coating materials is crucial for the preservation of cultural heritage. The purpose of this study was to evaluate the protective effect of Coromandel coatings on wooden substrates by analyzing their dimensions, weight, adhesion strength, hydrophobicity, and glossiness. The results indicate that after five cycles, the radial moisture expansion rate of the wood specimen is 0.332%, while that of the lacquer specimen is 0.079%, representing 23.8% of the radial moisture expansion rate of untreated wood specimens. This performance is superior to that of the ash and pigment specimens. Across different experimental conditions, the change in the mass of the Coromandel specimens aligns with the trend in their dimensional changes, indicating that moisture absorption and desorption are the primary reasons for dimensional changes. The influence of temperature on mass and dimensional stability is significant only in terms of dry shrinkage rate. After wet and dry cycles at 40 °C, the adhesion strength of the Coromandel specimens decreases the most, with the ash specimens decreasing by 7.2%, the lacquer specimens by 3.2%, and the pigment specimens by 4.5%. Following wet and dry cycles at three different temperatures, the contact angle of the lacquer layers changes by less than 5%, with their contact angle values exceeding 120°. These data indicate that among the Coromandel coatings, the lacquer layer provides the best protection for the wooden substrate, while the ash coating is the most fragile. The degradation rate of the Coromandel specimens increases with rising temperatures. These findings emphasize the critical roles of humidity and temperature in protecting wooden coatings and aim to provide theoretical insights and practical significance for the preservation of wooden artifacts and the assessment of coating performance.