Gypsum-based Silica Gel Humidity-controlling Composite Materials:Preparation,Characterization,and Performance

Gypsum was used as substrate,and silica gel was mixed into substrate at a certain mass ratio to prepare humidity-controlling composites;moreover,the moisture absorption and desorption properties of gypsum-based composites were compared with adding different silica gel particle size and proportion.The morphological characteristics,the isothermal equilibrium moisture content curve,moisture absorption and desorption rate,moisture absorption and desorption stability,and humidity-conditioning performance were tested and analyzed.The experimental results show that,compared with pure-gypsum,the surface structure of the gypsum-based composites is relatively loose,the quantity,density and aperture of the pores in the structure increase.The absorption and desorption capacity increase along with the increase of silica gel particle size and silica gel proportion.When 3 mm silica gel particle size is added with a mass ratio of 40%,the maximum equilibrium moisture content of humidity-controlling composites is 0.161 g/g at 98% relative humidity(RH),3.22 times that of pure-gypsum.The moisture absorption and desorption rates are increased,the equilibrium moisture absorption and desorption rates are 2.68 times and 1.61 times that of pure-gypsum at 58.5% RH,respectively.The gypsum-based composites have a good stability,which has better timely response to dynamic humidity changes and can effectively regulate indoor humidity under natural conditions.

The Evaluation of the Dietary Habits Influence on the Microhardness of Gingiva-Coloured Composite and Acrylic Denture Base Materials

Purpose: The study investigated the impact of dietary habits, specifically soda, milk kefir, water kefir, almond milk, and distilled water (control) consumption, on the microhardness of gingiva-coloured composite and acrylic denture bases. Methods: Materials included gingiva-coloured composite (Fusion Universal G1), acrylic (Imicryl), and subdivided Procryla group. Subgroups comprised 15 and 30-minute heat polymerized (Pro15, Pro30), and 1 wt% (Pro1Z) and 3 wt% (Pro3Z) zirconium added groups. Immersed in beverages for 1, 7, and 14 days, pH and microhardness were assessed. SEM examined random samples. Statistical analysis used repeated measures ANOVA, and post hoc tests (p Results: The gingiva-coloured composites displayed noteworthy time-associated microhardness changes (p 0.05). Despite variable pH levels in beverages, no substantial group interaction effects were observed (p > 0.05). Initial microhardness rankings shifted after a 14-day immersion. Conclusions: Gingiva-coloured composite exhibited the highest microhardness pre- and post-immersion, followed by Procryla30 and Imicryl groups. .

Effect of the Retarder on Initial Hydration and Mechanical Properties of the"one-step"Alkaliactivated Composite Cementitious Materials

This paper studied the effects of different retarders on the performance of the"one-step"alkali-activated composite cementitious material(ACCM)which is composed of ground granulated blast slag(GGBS)and fly ash(FA),and analyzed its mechanical properties,hydration mechanism,and retardation mechanism.The effects of retarders on the hydration products,mechanical properties,and hydration kinetics of ACCM were investigated using XRD,SEM,FTIR,EDS,and thermoactive microcalorimetry.The results showed that Na_(2)B_(4)O_(7)·10H_(2)O(B)delayed the exotherm during the alkali activation process and could effectively delay the setting time of ACCM,but the mechanical properties were slightly decreased.The setting time of ACCM increased with the increase in SG content,but the mechanical properties of ACCM decreased with the increase in SG content.C1_(2)H_(22)O_(11)(CHO)could effectively delay the hydration reaction of ACCM and weakly enhanced the compressive strength.H_(3)PO_(4)(HP)at a concentration of 0.05 mol/L had a certain effect on ACCM retardation,but HP at a concentration of 0.07 and 0.09 mol/L had an effect of promoting the setting and hardening time of ACCM.

Physical and Thermo-Mechanical Properties of Composite Materials Based on Raw Earth and Crushed Palm Leaf Fibers (Borassus aethiopum)

The objective of this study is to seek solutions to reduce the impact of buildings on climate change and to promote the use of local bio-sourced or geo-sourced materials for sustainable construction. Different samples of raw earth from 3 sites were taken in the commune of Mlomp. Geotechnical tests showed that the raw earth samples from sites 2 and 3 have more clay fraction while site 1 contains more sand. The fact of integrating fibers from crushed palm leaves (Borassus aethiopum) (2%, 4% and 6%) into the 3 raw earth samples reduced the mechanical resistance to compression and traction of the 3 raw earths. The experimental results of thermal tests on samples of earth mixtures with crushed Palma leaf fibers show a decrease in thermal conductivity as well as thermal effusivity as the percentages increase (2%, 4% and 6%) of fibers in raw earth for the 3 sites. This shows that this renewable composite material can help improve the thermal insulation of building envelopes.

Research Progress of Carbon-Silicone Composite Materials

Silicone is a kind of polymer material with high cross-linked structure,which is com-posed by Si-O-Si main chain.Due to the special molecular chain structure,silicone mate-rials are characterized by oxidation resistance,aging resistance,high and low temperature resistance and chemical corrosion resistance.Moreover,silicone materials have process-able properties,simple forming process,good mechanical property,non-toxic and pollution-free.Therefore,silicone has been widely concerned by researchers at home and abroad.In this paper,the main research progress and application directions of carbon-silicone composite at home and abroad in recent years are reviewed.

Research Progress on the Preparation of Inorganic/Natural Materials Composite Microspheres

Microspheres are a new type of drug carrier with great potential for development and application.Natural polymers have good biocompatibility,biodegradability,and are easily dispersed in living organisms,making them suitable for preparing microspheres.Inorganic materials(mainly inorganic minerals)have excellent mechanical properties and are inexpensive and easy to obtain.Through the coupling and hybridization of natural polymers and inorganic materials,they can complement each other's advantages and synergistically enhance efficiency,resulting in many excellent physical and chemical properties.Inorganic materials/natural polymer composite microspheres can be prepared by modifying natural polymers with inorganic materials through various methods such as emulsification crosslinking,solution mixing,in-situ synthesis,extrusion,etc.The application of inorganic materials/natural polymer composite microspheres in drug delivery systems has significant sustained-release effects,is safe and non-toxic,and the cost of carrier materials is relatively low,which has certain significance for the development of new drug carriers.This article reviews the recent research on the preparation,drug loading and release properties of inorganic material/natural polymer composite microspheres,analyzes the advantages and disadvantages of commonly used preparation methods,and looks forward to the development direction of composite microspheres.

Exploration on the Optimization Strategy for the Layup of Composite Material Pressure Vessels Based on Advanced Algorithms

This study aims to explore the influence of the laying angle on the pressure shell structure made of composite materials under the condition of a fixed shape. By using a composite material composed of a mixture of T800 carbon fiber and AG80 epoxy resin to design pressure vessels, this material combination can significantly improve the interlaminar shear strength and heat resistance. The article elaborates on the basic concepts and failure criteria of composite materials, such as the maximum stress criterion, the maximum strain criterion, the Tsai-Hill criterion, etc. With the help of the APDL parametric modeling language, the arc-shaped, parabolic, elliptical, and fitting curve-shaped pressure vessel models are accurately constructed, and the material property settings and mesh division are completed. Subsequently, APDL is used for static analysis, and the genetic algorithm toolbox built into Matlab is combined to carry out optimization calculations to determine the optimal laying angle. The research results show that the equivalent stress corresponding to the optimal laying angle of the arc-shaped pressure vessel is 5.3685e+08 Pa, the elliptical one is 5.1969e+08 Pa, the parabolic one is 5.8692e+08 Pa, and the fitting curve-shaped one is 5.36862e+08 Pa. Among them, the stress distribution of the fitting curve-shaped pressure vessel is relatively more uniform, with a deformation of 0.568E−03 m, a minimum equivalent stress value of 0.261E+09 Pa, a maximum equivalent stress value of 0.537E+09 Pa, and a ratio of 0.48, which conforms to the equivalent stress criterion. In addition, the fitting curve of this model can adapt to various models and has higher practical value. However, the stress distribution of the elliptical and parabolic pressure vessels is uneven, and their applicability is poor. In the future, further exploration can be conducted on the application of the fitting curve model in composite materials to optimize the design of pressure vessels. This study provides important theoretical support and practical guidance for the design of composite material pressure vessels.

TiO2-PES Fibrous Composite Material for Ammonia Removal Using UV-A Photocatalyst

This study focused on the development and characterization of TiO2-PES composite fibers with varying TiO2 loading amounts using a phase inversion process. The resulting composite fibers exhibited a sponge-like structure with embedded TiO2 nanoparticles within a polymer matrix. Their photocatalytic performance for ammonia removal from aqueous solutions under UV-A light exposure was thoroughly investigated. The findings revealed that PeTi8 composite fibers displayed superior adsorption capacity compared to other samples. Moreover, the study explored the impact of pH, light intensity, and catalyst dosage on the photocatalytic degradation of ammonia. Adsorption equilibrium isotherms closely followed the Langmuir model, with the results indicating a correlation between qm values of 2.49 mg/g and the porous structure of the adsorbents. The research underscored the efficacy of TiO2 composite fibers in the photocatalytic removal of aqueous under UV-A light. Notably, increasing the distance between the photocatalyst and the light source resulted in de-creased hydroxyl radical concentration, influencing photocatalytic efficiency. These findings contribute to our understanding of TiO2 composite fibers as promising photocatalysts for ammonia removal in water treatment applications.

Enhanced microwave absorption property of silver decorated biomass ordered porous carbon composite materials with frequency selective surface incorporation

Porous carbon(PC)is a promising electromagnetic(EM)wave absorbing material thanks to its light weight,large specific surface area as well as good dissipating capacity.To further improve its microwave absorbing performance,silver coated porous carbon(Ag@PC)is synthesized by one-step hydro-thermal synthesis process making use of fir as a biomass formwork.Phase compositions,morphological structure,and microwave absorption capability of the Ag@PC has been explored.Research results show that the metallic Ag was successfully reduced and the particles are evenly distributed inward the pores of the carbon formwork,which accelerates graphitization process of the amorphous carbon.The Ag@PC composite without adding polyvinyl pyrrolidone(PVP)exhibits higher dielectric constant and better EM wave dissipating capability.This is because the larger particles of Ag give rise to higher electric conductivity.After combing with frequency selective surface(FSS),the EM wave absorbing performance is further improved and the frequency region below-10 d B is located in8.20-11.75 GHz,and the minimal reflection loss value is-22.5 dB.This work indicates that incorporating metallic Ag particles and FSS provides a valid way to strengthen EM wave absorbing capacity of PC material.

Mechanical behavior of entangled metallic wire materials-polyurethane interpenetrating composites

Composite materials exhibit the impressive mechanical properties of high damping and stiffness,which cannot be attained by employing conventional single materials.Along these lines,a novel material architecture is presented in this work in order to fabricate composites with enhanced mechanical characteristics.More specifically,entangled metallic wire materials were used as the active matrix,whereas polyurethane was employed as the reinforcement elements.As a result,an entangled metallic wire material-polyurethane composite with high damping and stiffness was prepared by enforcing the vacuum infiltration method.On top of that,the mechanical properties(loss factor,energy consumption,and average stiffness)of the proposed composite materials were characterized by performing dynamic tests,and its fatigue characteristics were verified by the micro-interface bonding,as well as the macro-damage factor.The impact of the density,preloading spacing,loading amplitude,and exciting frequency on the mechanical properties of the composites were also thoroughly analyzed.The extracted results indicate that the mechanical properties of the composites were significantly enhanced than those of the pure materials due to the introduction of interface friction.Moreover,the average stiffness of the composites was about 10 times the respective value of the entangled metallic wire material.Interestingly,a rise in the loading period leads to some failure between the composite interfaces,which reduces the stiffness property but enhances the damping dissipation properties.Finally,a comprehensive dynamic mechanical model of the composites was established,while it was experimentally verified.The proposed composites possess higher damping features,i.e.,stiffness characteristics,and maintain better fatigue characteristics,which can broaden the application range of the composites.In addition,we provide a theoretical and experimental framework for the research and applications in the field of metal matrix composites.

Durability Testing of Composite Aerospace Materials Based on a New Polymer Carbon Fiber-Reinforced Epoxy Resin

In this study,the durability of a new polymer carbonfiber-reinforced epoxy resin used to produce composite material in the aerospacefield is investigated through analysis of the corrosion phenomena occurring at the microscopic scale,and the related infrared spectra and thermal properties.It is found that light and heat can con-tribute to the aging process.In particular,the longitudinal tensile strength displays a non-monotonic trend,i.e.,itfirst increases and then decreases over time.By contrast,the longitudinal compressive and inter-laminar shear strengths do not show significant changes.It is also shown that the inter-laminar shear strength of carbonfiber/epoxy resin composites with inter-laminar hybrid structure is better than that of pure carbonfiber materials.The related resistance to corrosion can be improved by more than 41%.

A Comparative Investigation of the Biodegradation Behaviour of Linseed Oil-Based Cross-Linked Composites Filled with Industrial Waste Materials in Two Different Soils

The biodegradation of polymeric biocomposites formed from epoxidized linseed oil and various types of fillers(pine needles,pine bark,grain mill waste,rapeseed cake)and a control sample without filler was studied during 180 days of exposure to two types of forest soil:deciduous and coniferous.The weight loss,morphological,and structural changes of polymer composites were noticed after 180 days of the soil burial test.The greatest weight loss of all tested samples was observed in coniferous forest soil(41.8%–63.2%),while in deciduous forest soil,it ranged between 37.7%and 42.3%.The most significant changes in the intensities of the signals evaluated by attenuated total reflectance infrared spectroscopy,as well as morphological changes determined by scanning electron microscopy,were assessed for polymer composite with rapeseed cake and specimen without filler in coniferous forest soil and are in a good agreement with weight loss results.Whereas significantly lower changes in weight loss,morphology,and structure of polymeric film with pine bark were noticed in both soils.It was suggested that fungi of Trichoderma,Penicillium,Talaromyces and Clonostachys genera are the possible soil microorganisms that degrade linseed oil-based cross-linked polymer composites.Moreover,the novel polymer composites have the potential to be an environmentally friendly alternative to petroleum-based mulching films.

Deformation Characteristics and Mechanical Properties of Ti/Al Bimetallic Composite Materials Fabricated by Wire Plus Arc Additive Manufacturing

We focused on Ti/Al composite materials fabricated by wire and arc addictive manufacturing,and the microstructure and interface characteristics of them before and after hot compression deformation were compared.After compression deformation,allαstructures of titanium were compacted with the emergence of Widmanstatten structures.Coarsened coloniesαof titanium were elongated and waved along the original growth direction,resulting in anisotropy of grains.Pores and Ti/Al intermetallic compounds of aluminum are significantly decreased after hot compression.Meanwhile,a good bonding interface between titanium and aluminum is obtained after hot compression,and the element diffusion is more intense.In addition,the mechanical properties and fracture behaviors of Ti/Al composite material with different clad ratio that is defined as the ratio of the thickness of titanium to that of the Ti/Al composite material are investigated by uniaxial tensile test.The experimental results show that the ultimate tensile strength of Ti/Al composite material is between that of single deposited titanium and aluminum,while the elongation of Ti/Al composite material with low clad ratio is lower than that of single aluminum due to the metallurgical reaction.As the clad ratio increases,the two component layers are harder to separate during deformation,which is resulted from the decrease of the inward contraction stress of three-dimensional stress caused by necking of aluminum.This work may promote the engineering application of Ti/Al bimetallic structures.

Machine learning-based stiffness optimization of digital composite metamaterials with desired positive or negative Poisson's ratio

Mechanical metamaterials such as auxetic materials have attracted great interest due to their unusual properties that are dictated by their architectures.However,these architected materials usually have low stiffness because of the bending or rotation deformation mechanisms in the microstructures.In this work,a convolutional neural network(CNN)based self-learning multi-objective optimization is performed to design digital composite materials.The CNN models have undergone rigorous training using randomly generated two-phase digital composite materials,along with their corresponding Poisson's ratios and stiffness values.Then the CNN models are used for designing composite material structures with the minimum Poisson's ratio at a given volume fraction constraint.Furthermore,we have designed composite materials with optimized stiffness while exhibiting a desired Poisson's ratio(negative,zero,or positive).The optimized designs have been successfully and efficiently obtained,and their validity has been confirmed through finite element analysis results.This self-learning multi-objective optimization model offers a promising approach for achieving comprehensive multi-objective optimization.

Materials Selection of Thermoplastic Matrices of Natural Fibre Composites for Cyclist Helmet Using an Integration of DMAIC Approach in Six Sigma Method Together with Grey Relational Analysis Approach

Natural fibre reinforced polymer composite(NFRPC)materials are gaining popularity in the modern world due to their eco-friendliness,lightweight nature,life-cycle superiority,biodegradability,low cost,and noble mechanical properties.Due to the wide variety of materials available that have comparable attributes and satisfy the requirements of the product design specification,material selection has become a crucial component of design for engineers.This paper discusses the study’s findings in choosing the suitable thermoplastic matrices of Natural Fibre Composites for Cyclist Helmet utilising the DMAIC,and GRA approaches.The results are based on integrating two decision methods implemented utilising two distinct decision-making approaches:qualitative and quantitative.This study suggested thermoplastic polyethylene as a particularly ideal matrix in composite cyclist helmets during the selection process for the best thermoplastic matrices material using the 6σtechnique,with the decision based on the highest performance,the lightest weight,and the most environmentally friendly criteria.The DMAIC and GRA approach significantly influenced the material selection process by offering different tools for each phase.In the future study,selection technique may have been more exhaustive if more information from other factors had been added.

Influence of Some Plant Fibers on the Mechanical Performance of Composite Materials

This work focused on the search for biobased materials capable of being used in road techniques as soil inclusions, and on studying the influence of their incorporation on the characteristic parameters of pavement layers. To this end, pineapple, cyperus and imperata plant fibers, due to their endemic availability, were used as reinforcement on sourced materials, notably bar soil, lateritic gravel and silty sand. Complete identification and mechanical tests (Proctor and CBR) were carried out on materials in their natural state (soil) and on composite materials (soil + plant fibers) in the laboratory to determine their classification in road geotechnics, their compaction parameters and their mechanical behavior. Firstly, the various types of 2.5 cm long fibers were incorporated into the different types of soil at mass contents of 1% and 2%. This part of the study showed that the pineapple fiber composite incorporated into class A2 bar soil offered the best results, with a 38% gain in CBR index compared with the natural soil. Pineapple fibers incorporated at 1% in lateritic gravel raise the CBR value of the reinforced soil to 10% of the CBR value of the natural soil and to 7% for silty sand.

Wear behavior of SiC/PyC composite materials prepared by electromagnetic-field-assisted CVI

Silicon carbide/pyrolytic carbon (SiC/PyC) composite materials with excellent performance of self-lubrication and wear resistance were prepared on SiC substrates by electromagnetic-field-assisted chemical vapor infiltration (CVI). The composition and microstructure of the SiC/PyC materials were investigated in detail by XRD, SEM and EDS, etc. The effects of the deposition temperature on the section features and wear resistance of the SiC/PyC were studied. The results show that the PyC layers were deposited onto SiC substrates spontaneously at a lower deposition temperature. The SiC substrates deposited with PyC can significantly reduce the wear rate of the self-dual composite materials under dry sliding condition. The wear tests suggest that the SiC/PyC composite materials own a better wear resistance property when the deposition temperature is 800 °C, and the wear rate is about 64.6% of that without the deposition of PyC.

Effects of current density on preparation and performance of Al/conductive coating/α-PbO_2-Ce O_2-TiO_2/β-Pb O_2-MnO_2-WC-ZrO_2 composite electrode materials

Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique. The effects of current density on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated by energy dispersive X-ray spectroscopy（EDXS）, anode polarization curves, quasi-stationary polarization（Tafel） curves, electrochemical impedance spectroscopy（EIS）, scanning electron microscopy（SEM）, and X-ray diffraction（XRD）. Results reveal that the composite electrode obtained at 1 A/dm2 possesses the lowest overpotential（0.610 V at 500 A/m2） for oxygen evolution, the best electrocatalytic activity, the longest service life（360 h at 40 °C in 150 g/L H2SO4 solution under 2 A/cm2）, and the lowest cell voltage（2.75 V at 500 A/m2）. Furthermore, with increasing current density, the coating exhibits grain growth and the decrease of content of Mn O2. Only a slight effect on crystalline structure is observed.

Development and application of novel high‐efficiency composite ultrafine cement grouts for roadway in fractured surrounding rocks

The fractured surrounding rocks of roadways pose major challenges to safe mining.Grouting has often been used to reinforce the surrounding rocks to mitigate the safety risks associated with fractured rocks.The aim of this study is to develop highly efficient composite ultrafine cement(CUC)grouts to reinforce the roadway in fractured surrounding rocks.The materials used are ultrafine cement(UC),ultrafine fly ash(UF),ultrafine slag(US),and additives(superplasticizer[SUP],aluminate ultrafine expansion agent[AUA],gypsum,and retarder).The fluidity,bleeding,shrinkage,setting time,chemical composition,microstructure,degree of hydration,and mechanical property of grouting materials were evaluated in this study.Also,a suitable and effective CUC grout mixture was used to reinforce the roadway in the fractured surrounding rock.The results have shown that the addition of UF and US reduces the plastic viscosity of CUC,and the best fluidity can be obtained by adding 40%UF and 10%US.Since UC and UF particles are small,the pozzolanic effect of UF promotes the hydration reaction,which is conductive to the stability of CUC grouts.In addition,fine particles of UC,UF,and US can effectively fill the pores,while the volumetric expansion of AUA and gypsum decreases the pores and thus affects the microstructure of the solidified grout.The compressive test results have shown that the addition of specific amounts of UF and US can ameliorate the mechanical properties of CUC grouts.Finally,the CUC22‐8 grout was used to reinforce the No.20322 belt roadway.The results of numerical simulation and field monitoring have indicated that grouting can efficaciously reinforce the surrounding rock of the roadway.In this research,high‐performance CUC grouts were developed for surrounding rock reinforcement of underground engineering by utilizing UC and some additives.

Microstructure and ablation behavior of Zr-based ultra-high-temperature gradient composites

To obtain high-performance Zr-based ultra-high-temperature composites,Zr-based ultra-high-temperature gradient composites were prepared by changing the laying method of the infiltrant via reactive melt infiltration.The effects of different infiltrant laying methods on the microstructure and ablative properties of Zr-based ultrahigh-temperature gradient composites were investigated.The results showed that the gradient structure of the Zr-based ultrahigh-temperature gradient composites differed when the composition ratio of the infiltrant was changed.When the thicknesses of the Zr/Mo/Si layers were 6/4/12 mm and 8/2/12 mm,the SiMoZrC solid solution content in the samples increased and decreased along the infiltration direction,respectively.The gradient samples were ablated in an oxyacetylene flame at 3000°C for 40 s.The ablation resistance of the sample was the highest when the infiltrant was a powder and the thickness of the Zr/Mo/Si layer was 6/4/12 mm.