Surface Of Composite Material Research Articles

Influence of Different Environmental Factors on the Aging of Corn Straw/Polycarbonate (PPC)/Polylactic Acid (PLA) Composite Materials.

This study aims to gain a deeper understanding of the effects of different environmental factors on the mechanical properties, surface morphology, and microstructure of corn straw/polycarbonate/poly(lactic acid) composite materials. Three different aging methods, namely wet heat aging, natural aging, and oxidative thermal aging, were used to investigate the effects of high temperature, humidity, and light on the mechanical properties, surface morphology, and microstructure of the composite materials. The surface morphology, chemical, thermal properties, and crystallization behavior of aged samples were analyzed using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and multifunctional X-ray diffraction, respectively. Research findings reveal the impact of environmental factors as follows: First, elevated-temperature environments induce plastic degradation and activation of polymer molecular chains, significantly reducing the mechanical properties of composite materials. Specifically, the flexural and impact strengths experience reductions of 57.6 and 30.3%, respectively. Second, elevated humidity leads to the infiltration of water molecules, causing changes in the internal structure of composite materials. It, in turn, diminishes the bonding degree between fibers and plastics, induces surface cracks, and adversely affects mechanical properties. Consequently, flexural and impact strengths are reduced by 58.1 and 7.2%, respectively. Third, exposure to light triggers lignin photo-oxidation, causing the surface of composite materials to fade, △E increased by 19.28%.

P-doped g-C3N4/BiOCl Z-type heterojunction with N and O double vacancies and synergistically enhanced photocatalytic activity under sunlight irradiation

The use of inexhaustible natural sunlight is a highly effective method for wastewater treatment. In this study, P-doped g-C3N4/BiOCl Z-type heterojunction semiconductor photocatalyst with N and O double vacancies was constructed through calcination and coprecipitation. The obtained results revealed that the degradation rate of Rhodamine B (Rh B) reached 0.05642 min −1 within 60 min under visible light irradiation with a 300 W xenon lamp (λ≥400 nm), which was 73 and 8 times that of pure CN and BiOCl, respectively. Under natural sunlight irradiation, Rh B was almost completely degraded within 6 min, and its degradation rate reached 0.95641 min−1, which was 17 times that of Rh B simulated by visible light in the laboratory. The doping of non-metallic P and construction of a heterojunction significantly improved the photocatalytic activity of P-doped g-C3N4/BiOCl, which could be attributed to the synergistic effect of N, O vacancies and heterojunction structure interfaces on the composite material surface, which apparently expanded the light absorption range, promoted the transfer of charge, increased the quantity of active sites for the light-induced reaction, and improved the redox ability of the catalyst. The heterojunction semiconductor with surface defects prepared in this study provides a green approach for future wastewater treatment applications.

Study on the mechanical properties of layered gradient structure PBT-based flame retardant composite materials

Abstract To enhance the flame retardancy of Polybutylene Terephthalate (PBT) based composite materials and overcome the decrease in mechanical properties due to the high content of nano-antimony trioxide (nano-Sb2O3), this study initially applies a composite modification method to treat the surface of nano-Sb2O3. Subsequently, composite materials with a gradient distribution of nano-Sb2O3 are prepared through lamination hot-pressing technology, and their mechanical and flame retardant properties are investigated. The results show that the modifiers CTAB and KH560 are successfully grafted onto the surface of nano-Sb2O3, altering its surface properties. Through lamination hot-pressing technology, a gradient distribution from the surface to the core is achieved. Compared to the homogeneous distribution P666, G828 exhibits a 6% increase in Limiting Oxygen Index (LOI), improving the flame retardancy of the composite material. As nano-Sb2O3 enriches on the composite material's surface, the amount of char residue increases. The tensile strength, bending strength, and impact strength of G828 composite material increase by 19.7%, 37.1%, and 103%, respectively, compared to the homogeneous composite material P666, proving the significant effect of G828's gradient distribution in enhancing the mechanical properties of the composite material.

Efficient Capture of Phosphate From Aqueous Media Using Bimetallic La‐Zr‐MOF

ABSTRACTDeposition of excessive phosphate in natural water column caused several issues, like the eutrophication and destruction of aquatic ecosystems. Adsorption has been an effective and convenient method for phosphate elimination. Herein, a novel bimetallic metal–organic framework adsorbent, namely, La‐Zr‐MOF, was prepared, and the morphology, crystallite, characteristic functional groups, specific surface area, and composite material surfaces were analyzed using XRD, FT‐IR, SEM‐EDS, and BET. The adsorption performance of the adsorbent was systematically evaluated by batch adsorption experiments, and the adsorption thermodynamic and kinetic properties were analyzed. The results reveal that La‐Zr‐MOF exhibits a high selectivity and sorption performance for phosphate, and the adsorption of La‐Zr‐MOF follows the Langmuir and pseudo–second‐order models; the phosphate removal procedure is a chemisorption accompanied by an endothermic reaction, and the maximum capacity was 127.7 mg g−1. Combined with batch adsorption experiments, kinetic and thermodynamic studies and various characterization analyses together revealed the phosphate removal mechanism, mainly ligand exchange and electrostatic interactions.

Nanocarbon-Polymer Composites for Next-Generation Breast Implant Materials.

Most breast implants currently used in both reconstructive and cosmetic surgery have a silicone outer shell, which, despite much progress, remains susceptible to mechanical failure, infection, and foreign body response. This study shows that the durability and biocompatibility of breast implant-grade silicone can be enhanced by incorporating carbon nanomaterials of sp2 and sp3 hybridization into the polymer matrix and onto its surface. Plasma treatment of the implant surface can be used to modify platelet adhesion and activation to prevent thrombosis, postoperative infection, and inflammation disorders. The addition of 0.8% graphene flakes resulted in an increase in mechanical strength by 64% and rupture strength by around 77% when compared to pure silicone, whereas when nanodiamond (ND) was used as the additive, the mechanical strength was increased by 19.4% and rupture strength by 37.5%. Composites with a partially embedded surface layer of either graphene or ND showed superior antimicrobial activity and biocompatibility compared to pure silicone. All composite materials were able to sustain the attachment and growth of human dermal fibroblast, with the preferred growth noted on ND-coated surfaces when compared to graphene-coated surfaces. Exposure of these materials to hydrogen plasma for 5, 10, and 20 s led to substantially reduced platelet attachment on the surfaces. Hydrogen-treated pure silicone showed a decrease in platelet attachment for samples treated for 5-20 s, whereas silicone composite showed an almost threefold decrease in platelet attachment for the same plasma treatment times. The absence of platelet activation on the surface of composite materials suggests a significant improvement in hemocompatibility of the material.

Development of superhydrophilic ZnOX/TiO2 with visible light-induced self-cleaning and antibacterial properties

Many studies aimed to improve the antibacterial ability and applicability of antibacterial surface materials by altering their chemical composition and structure. In this study, we successfully prepared a multifunctional ZnOX/TiO2 (0<X ≤ 2) nanocomposites by a sol-gel method, which exhibits visible light responsive self-cleaning, antibacterial adhesion, and antimicrobial properties. In the comparison of the three zinc sources, it was found that the ZnOX/TiO2 prepared with zinc sulfate doping had a water contact angle of only 1.7°, with enhanced hydrophilicity, and exhibited the best photocatalytic activity under visible light, with a removal rate of up to 90.2% of methylene orange (MO). Antibacterial tests revealed the average diameters of the inhibition halos for Escherichia coli and Staphylococcus aureus were 10 and 12 mm, respectively, thereby showing excellent antibacterial activity under visible light. The low photogenerated electron-hole recombination and the high rates of ·OH and ·O2- generation through photo-induced interface charge transfer in ZnOX/TiO2 composite, which is the main reason for enhancing the photocatalytic antibacterial activity under visible light irradiation. Release of Zn2+ species, resulting in significant antibacterial performance even under dark conditions. This study combines doping and surface modification, introduce abundant surface hydroxyl groups to endow the composite material surface with superhydrophilicity, anti-bacterial adhesion, and antibacterial properties that can meet the needs of clean and antibacterial surfaces in medical.

Development of polyurethane urea（PUU）– Waste rubber particles (WRP) composite materials for active ice-breaking of groove-filled asphalt pavement

The grooved-filled asphalt pavement has certain advantages in terms of pavement ice-breaking and anti-skid. However, the performances of the filling material limit its development. In this study, a polyurethane urea (PUU) - waste rubber particles (WRP) composite filling material was prepared by using a polyurethane (PU) and adding polyurea (PUa) with a similar microstructure as the cementing material, and adding WRP as the elastic reinforcing phase. The proportions of nine PUU-WRP composite materials were designed by changing the particle size and content of WRP, and then the filled composite materials were evaluated in terms of physical and mechanical properties, ice adhesion properties, interface bonding properties and aging resistance. The test results showed that the shore hardness, tensile strength, compression permanent deformation, and contact angle of PUU-WRP composite decreased as content of the WRP increased. Except the ice adhesion force results were the opposite. On the other hand, increased the WRP size resulted in increase in PUU-WRP composite’s shore hardness, compression permanent deformation, and ice adhesion force, while the tensile strength and contact angle were the opposite. The surface of the PUU-WRP composite material was hydrophobic, and the maximum contact angle was 102.3°. The reduction of WRP particle size and dosage was beneficial for reducing the ice adhesion force on the surface of PUU-WRP composite materials. The maximum interfacial shear and tensile strength of PUU-WRP composite material were 1.082 MPa and 0.244 MPa, respectively. After 42 days of UV aging, the maximum attenuation rate did not exceed 30 %. After the immersion test, the tensile strength attenuation of PUU-WRP composite material was basically controlled within 10 %. Finally, based on the fuzzy comprehensive evaluation (FCE) method, it was recommended to use WRP with a particle size of 0.6 mm and a dosage of 30 wt%-40 wt%.

Prospects of coating application for improving surface properties of cast composite materials

Foundry production is a versatile industry that allows the production of products of almost any configuration and geometric dimensions. These products can be made from materials based on various metals and alloys, bimetallics, and composite materials. The obtained products can have uniform or gradient properties. However, to obtain a product with significantly different properties on the surface and in the volume from the casting, it is expedient to apply coatings with desired properties on the castings that complement the properties, allowing the improvement of coating performance. The paper focuses on the production of cast composite materials with improved surface properties. Various types of coatings based on high‑entropy alloys, cermets, polymers, carbon nanotubes, capable of enhancing the properties of cast composite materials, are considered. The classification and peculiarities of applying these coatings on the surface of composite materials are presented. The prospects of using these coatings to improve the properties of cast composite materials are shown.

A Visual Measurement Method for Deep Holes in Composite Material Aerospace Components.

The visual measurement of deep holes in composite material workpieces constitutes a critical step in the robotic assembly of aerospace components. The positioning accuracy of assembly holes significantly impacts the assembly quality of components. However, the complex texture of the composite material surface and mutual interference between the imaging of the inlet and outlet edges of deep holes significantly challenge hole detection. A visual measurement method for deep holes in composite materials based on the radial penalty Laplacian operator is proposed to address the issues by suppressing visual noise and enhancing the features of hole edges. Coupled with a novel inflection-point-removal algorithm, this approach enables the accurate detection of holes with a diameter of 10 mm and a depth of 50 mm in composite material components, achieving a measurement precision of 0.03 mm.

A comprehensive XPS investigation of the effect of aqueous corrosion on the surface of glass-zirconolite composite material (Fe–Al–BG–CaZrTi2O7)

Extensive X-ray photoelectron spectroscopy (XPS) analyses of iron–aluminum borosilicate glass (Fe–Al–BG), zirconolite (CaZrTi2O7), and Fe–Al–BG–CaZrTi2O7 composite material have demonstrated that a hydrated layer has been formed on the surface of these materials after exposure to water. The surface chemistry of Fe–Al–BG–CaZrTi2O7 composite material as a potential nuclear wasteform candidate was observed to change in a similar fashion to the borosilicate glass as a current wasteform material after these materials are exposed to water. The XPS measurements suggest that the aqueous corrosion of the Fe–Al–BG–CaZrTi2O7 composite material is a result of ion exchange, hydrolysis, and redox reactions of metal–oxygen bonds with water at the surface of the Fe–Al–BG–CaZrTi2O7 composite material. Moreover, the XPS results proved that the composition and chemical environment of the precipitated layer on the surface of the Fe–Al–BG–CaZrTi2O7 composite material after exposure to water remained unchanged between 270 and 365 days of exposure to water. The stability of the surface layer during this time frame could potentially protect the surface of the Fe–Al–BG–CaZrTi2O7 composite material from further corrosion.

Microwave-assisted fabrication of 1D/2D CeO2/Bi2MoO6 heterojunction for efficient photocatalytic CO2 reduction to CH3OH

Photocatalytic CO2 reduction to fuels via visible light is regarded as a highly promising sustainable technology to address resource depletion and environmental apprehensions. However, the elevation of photocatalytic performance is limited due to some drawbacks of isolated catalysts such as poor CO2 adsorption performance, inadequate utilization of visible light, and rapid recombination of photo-generated carriers. Herein, a series of novel heterojunction catalysts, 1D/2D CeO2/Bi2MoO6 (CBMO-X), were fabricated utilizing the microwave-assisted method for the photocatalytic reduction of CO2. The CH3OH yield of the optimized CBMO-10 composite material reached 4.31 μmol⋅g−1⋅h−1 with excellent stability and structural integrity. Through a series of characterizations, it was found that the introduced CeO2 nanorods served as bifunctional sites for CO2 adsorption and photoelectron accumulation, effectively promoting CO2 conversion under visible light. In addition, CBMO-X exhibited faster photo-generated carriers migration rate due to the formation of the II-scheme heterojunction, which improved the photocatalytic performance obviously. Furthermore, the density functional theory (DFT) calculations and in situ XPS were used to investigate the carrier migration paths on the surface of composite materials. This work provided a novel strategy for the design of photocatalysts for efficient CO2 conversion.

Wetting, droplet evaporation and corrosion behavior of various composite and textured materials

Experimental studies were conducted on the evaporation rate of a droplet located on the surfaces of various composite and textured materials with different wettability at varying surface temperatures. The maximum droplet evaporation rate was recorded on a textured Cu–SiC composite material with superhydrophilic properties. The minimum droplet evaporation rate corresponded to a superhydrophobic AlMg3 substrate obtained using laser texturing with subsequent hydrophobization procedure. An increase in surface temperature led to a significant deterioration of hydrophobicity for a superhydrophobic substrate and a deterioration of hydrophilicity for a superhydrophilic substrate. As a result, with increasing temperature, the influence of the droplet geometry determined by surface wettability on the droplet evaporation rate for these substrates sharply decreases. Advancing and receding dynamic contact angles, as well as contact angle hysteresis were obtained on all studied substrates. It is generally accepted that a hydrophobic surface exhibits less contact angle hysteresis than a hydrophilic one. However, Cu-SiС composite substrate with a textured hydrophobic surface exhibited the opposite behavior. The contact angle hysteresis on the hydrophobic textured surface was found to be four times higher than that on the hydrophilic polished one. A mechanism was proposed that explains the high contact angle hysteresis and four hysteresis time modes. The minimum hysteresis value corresponded to the superhydrophobic AlMg3 substrate. Anti-corrosion properties were studied for all substrates under consideration. The minimum corrosion current corresponded to a copper substrate with a graphene coating, as well as a superhydrophobic AlMg3 substrate. For a given substrate, there are two corrosion modes with a three-fold difference in the corrosion current. In addition, the wettability behavior of different surfaces was examined using molecular dynamics simulations. The simulation results were found to be consistent with the experimental data.

Inspection of Surface Damage in Composite Materials with Different Techniques

Due to their excellent physical properties and high strength and stiffness relative to density, aerospace industry research is producing high-performance structural materials, such as composites, which are used in many critical structural parts like airframes, wings, rotor blades, propellers, and other components. However, during flight, these materials may be damaged by impact, thermal stress, moisture, and ultraviolet radiation. One of the most prevalent issues with composite materials is their challenging nature in terms of flaw detection during both manufacturing and use. When they are employed in the crucial areas that were previously indicated, this becomes a very serious issue. When evaluating the structural integrity of composites and looking for any damage, microscopes are a very useful instrument. Effective methods for identifying and analyzing damage include microscopic procedures like optical microscopy, stereomicroscopy, scanning electron microscopy (SEM), scanning ion microscopy (SIM), and atomic force microscopy (AFM). A variety of methods may be employed with microscopes to examine and identify deterioration in composite materials. It is often possible to examine overt deterioration on the surface of composite materials under the microscope utilizing a number of different approaches and procedures. Determining the kind, extent, distribution, and impact of the damage requires these inspections. Often employed techniques consist of: SEM is a method for high-resolution imaging of surface damage. It entails shining an electron beam onto the sample's surface and capturing pictures. SEM is a useful tool for identifying erosion, delamination, and microcracks. It is also possible to measure things like the damage's breadth and depth. Optical microscopes have a large field of view and look at damaged regions. This makes it possible to find tiny fractures or cracks that are invisible to the unaided eye. Furthermore, details on the degree of harm, the roughness of the surface, and the breadth and depth of the fractures may be acquired. To see damaged objects, optical microscopy is utilized. Cracks and damage locations are visible with optical microscopy. Optical microscopes can identify different kinds of damage by looking at the surface of the material. Damage like delamination, fiber breakage, cracks, and deformations are a few examples of these. This study examines the efficacy of microscopic methods and non-destructive testing in assessing the different kinds of damage that can occur at the interfaces between holes in composite materials. Composite test materials were chosen from glass fiber reinforced phenolic matrix composites that were produced in compliance with aerospace standards. The measurements led to the conclusion that using microscopic techniques has benefits like speed and field suitability. However, the continuous development and improvement of new methods in this field will contribute to a better understanding of layered composite materials and the development of safer and more durable structures.

Highly sensitive Ti3C2Tx MXenes-RGO humidity sensor for human non-contact respiratory monitoring

In this study, a highly sensitive and stable Ti3C2Tx MXenes-RGO humidity sensor was developed for real-time respiratory monitoring. Ti3C2Tx-RGO composite material increases the interlayer spacing of RGO, further expanding the channels for water molecule transport. Introduction of Ti3C2Tx promotes the generation of more -O, -OH, -F groups on the composite material surface, which can serve as adsorption sites for water molecules to improve response, and they form weak physical adsorption with water molecules, shortening the response and recovery time of the sensor. Ti3C2Tx-RGO composite material increases the interlayer spacing of RGO, further expanding the channels for water molecule transport. Density functional theory (DFT) calculation results indicate that Ti3C2Tx surface -F has higher adsorption energy for water molecules, which is beneficial for enhancing the sensitivity of the humidity sensor. Ti3C2Tx-RGO humidity sensor exhibits high sensitivity (22,117), low humidity hysteresis (1%), relatively short response/recovery time (7/16 s), and good stability and repeatability in the range of 11%− 95% RH. The sensor can also monitor changes in respiratory intensity and frequency, achieving real-time analysis of respiratory patterns, making it demonstrate strong application potential in non-contact human respiratory detection. This study provides new research ideas and methods for preparing high-performance humidity sensors.

Sand Erosion Resistance and Failure Mechanism of Polyurethane Film on Helicopter Rotor Blades.

Polyurethane is widely used on the surface of composite materials for rotor blades as sand erosion protection materials. The failure mechanism investigation of polyurethane film under service conditions is useful for developing the optimal polyurethane film for rotor blades. In this article, the sand erosion test parameters were ascertained according to the service environment of the polyurethane film. The sand erosion resistance and failure mechanism of polyurethane film at different impact angles were analyzed by an infrared thermometer, a Fourier transform infrared spectrometer (FTIR), a differential scanning calorimeter (DSC), a field emission scanning electron microscope (FESEM), and a laser confocal microscope (CLSM). The results show that the direct measurement method of volume loss can better characterize the sand erosion resistance of the polyurethane film compared to traditional mass loss methods, which avoids the influence of sand particles embedded in the polyurethane film. The sand erosion resistance of polyurethane film at low-angle impact is much lower than that at high-angle impact. At an impact rate of 220 m/s, the volume loss after sand erosion for 15 min at the impact angle of 30° is 57.8 mm3, while that at the impact angle of 90° is only 2.6 mm3. The volume loss prediction equation was established according to the experimental data. During low-angle erosion, the polyurethane film damage is mainly caused by sand cutting, which leads to wrinkling and accumulation of surface materials, a rapid increase in roughness, and the generation of long cracks. The linking of developing cracks would lead to large-scale shedding of polyurethane film. During high-angle erosion, the polyurethane film damage is mainly caused by impact. The connection of small cracks caused by impact leads to the shedding of small pieces of polyurethane, while the change in the roughness of the film is not as significant as that during low-angle erosion. The disordered arrangement of the soft and hard blocks becomes locally ordered under the action of impact and cutting loads. Then, the disordered state is restored after the erosion test finishes. The erosion of sand particles leads to an increase in the temperature of the erosion zone of the polyurethane film, and the maximum temperature rise is 6 °C, which does not result in a significant change in the molecular structure of the polyurethane film. The erosion failure mechanism is cracking caused by sand cutting and impact.

Activated carbon synthesized from Arecanut catechu L. as a sustainable precursor intercalated TiO2 modified electrode for the detection of fungicide Dichlorophen

Pesticides, such as dichlorophen (DCP), pose serious threats to the ecosystem and human health. Hence, developing an efficient and sensitive detection method is crucial for environmental monitoring and remediation. In this study, we present a novel composite material comprised of TiO2 intercalated areca nut husk-derived activated carbon for the ultrasensitive detection of dichlorophen. The activated carbon is derived through a well-established activation process using areca nut husk waste, a sustainable biomass material. The material's irregular structure and large surface area provide abundant adsorption sites for the target analyte, DCP. The integration of TiO2 nanoparticles further enhances the detection capability due to their exceptional catalytic properties. Upon exposure to DCP, their interaction with the surface of composite material leads to measurable changes in its electrical and chemical properties. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques are used to validate the performance of the fabricated electrode. The developed ultrasensitive detection method exhibits remarkable DL (detection limit, 1.01 × 10−8 M) and QL (quantification limit, 3.36 × 10−8 M) values, hence can be a promising alternative for environmental monitoring, industrial safety, and public health applications. The synergistic effect between activated carbon and TiO2 nanoparticles ensures a highly sensitive and selective response to DCP. Consequently, this advanced sensor system has great potential for detecting and quantifying dichlorophen concentrations in diverse environmental samples.

Effect of laser cleaning on adhesive properties of carbon fiber composite materials

A pulsed fiber laser was used to conduct laser cleaning experiments on the composite paint layer on the surface of carbon fiber composite materials (carbon fiber-reinforced plastic (CFRP)). The influence of laser energy density and laser travel speed on the cleaning effect was studied. The surface morphology, surface roughness and phase composition of the cleaned sample were analyzed. After bonding, tensile testing was conducted on the bonding part to verify the impact of laser cleaning on the bonding performance. The research results indicate that the cleaning effect gradually improves with the increase of laser energy density or the decrease of travel speed. In this experiment, when the laser energy density is 4.00[Formula: see text]J/cm2 and the travel speed is 6.5[Formula: see text]mm/s, the phase composition of the cleaned substrate surface is only C, without TiO2 and BaSO4. This indicates that the paint layer has been completely removed under this process parameter. By selecting reasonable process parameters, the surface paint layer of CFRP can be effectively removed, and a good surface morphology can be obtained without damage to the carbon fiber. Meanwhile, the mechanical properties after bonding can be improved.

Immobilization of β-cyclodextrin onto the surface of electrospun fibers as rapid and highly efficient adsorbent with good recyclability

It is still a big challenge to obtain adsorbents with high adsorption rate and improved adsorption capacity. Herein, we report a novel electrospun fibers adsorbent modified with carboxylated-β-cyclodextrin (CB-β-CD) molecules for the rapid and efficient removal of phenolphthalein (PHP) from water. First, CB-β-CD is synthesized by esterification of β-CD with succinic anhydride. Subsequently, by means of polydopamine (PDA) coating rich in amine groups, CB-β-CD is covalently bonded onto the surface of poly(vinylidene fluoride)@polystyrene/PDA (PVDF@PS/PDA) fibers through the amide linkage to obtain PVDF@PS/PDA/CB-β-CD fibers adsorbent. XPS, WCA and thermal properties results suggest that large amounts of CB-β-CD molecules hang over the surface of PVDF@PS/PDA/CB-β-CD fibers and the cavities of CB-β-CD molecules are well preserved, thus providing more sites to form inclusion complexes with guest molecules. The adsorbent exhibits excellent adsorption properties for PHP, with a saturation adsorption capacity of 39.97 mg/g after 10 min, which is superior to other reported adsorbents containing β-CD. Moreover, PVDF@PS/PDA/CB-β-CD shows good recyclability and highly selective adsorption of PHP, which has potential applications in molecular recognition, organic molecules separation, and water purification. The developed method provides a new strategy for immobilizing more β-CD molecules onto the surface of composite materials to endow superior comprehensive performances.

Preparation and performance of TiO2/ZnO humidity sensor based on TiO2

In this study, TiO2 was selected as the primary material to prepare a humidity sensor. To enhance its sensing performance, it was doped with ZnO, and a TiO2/ZnO composite was synthesized via the hydrothermal method. Based on this composite material, a TiO2/ZnO humidity sensor was designed and fabricated. The sensor properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) techniques. The increase in hydroxyl and oxygen vacancy content on the surface of composite materials enhances their sensitivity to water molecules, leading to improved sensor response. The construction of ZTO3 heterojunction promotes the migration of electrons on the sensor surface to improves the performance of the sensor. Humidity sensor based on the TiO2/ZnO composite material exhibits excellent performance, with high response to water molecules, a fast response/recovery time (18/22 s), low humidity hysteresis (1.55 %), and low interference from monochromatic light. Thus, the TiO2-based humidity sensor doped with ZnO shows great potential for practical applications.

Effects of Additives on the Mechanical and Fire Resistance Properties of Pultruded Composites.

Under high temperatures, fiber-reinforced polymers are destroyed, releasing heat, smoke, and harmful volatile substances. Therefore, composite structural elements must have sufficient fire resistance to meet the requirements established by building codes and regulations. Fire resistance of composite materials can be improved by using mineral fillers as flame-retardant additives in resin compositions. This article analyzes the effect of fire-retardant additives on mechanical properties and fire behavior of pultruded composite profiles. Five resin mixtures based on vinyl ester epoxy and on brominated vinyl ester epoxy modified with alumina trihydrate and triphenyl phosphate were prepared for pultrusion of strip profiles of 150 mm × 3.5 mm. A series of tests have been conducted to determine mechanical properties (tensile, flexural, compression, and interlaminar shear) and fire behavior (ignitability, flammability, combustibility, toxicity, smoke generation, and flame spread) of composites. It was found that additives impair mechanical properties of materials, as they the take place of reinforcing fibers and reduce the volume fraction of reinforcing fibers. Profiles based on non-brominated vinyl ester epoxy have higher tensile, compressive, and flexural properties than those based on brominated vinyl ester epoxy by 7%, 30%, and 36%, respectively. Profiles based on non-brominated epoxy resin emit less smoke compared to those based on brominated epoxy resin. Brominated epoxy-based profiles have a flue gas temperature which is seven times lower compared to those based on the non-brominated epoxy. Mineral fillers retard the spread of flame over the composite material surface by as much as 4 times and reduce smoke generation by 30%.