Γ-methacryloxypropyl Trimethoxy Silane Research Articles

Development and mechanical properties of nano SiO2 modified photosensitive resin for high-strength and high-brittleness 3D printing in rock reconstruction

3D printing technology, as a rapid prototyping method, can accurately reconstruct the internal structural characteristics of samples, making it highly promising for rock engineering applications. However, current 3D printing materials used to reconstruct rocks suffer from low strength and high ductility, which is inconsistent with the high strength and brittleness of natural rocks. This paper explores the use of silane coupling agents KH550 (γ-aminopropyl triethoxysilane) and KH570 (γ-methacryloxypropyl trimethoxysilane) to modify nano SiO2 powder. Through sample preparation and uniaxial compression tests, the mechanical properties and failure characteristics of the modified nano SiO2 powder were analyzed. The results indicate that, using the preparation method with a mass ratio of E-44 epoxy resin, KH550 modified nano SiO2 powder, and 593 curing agent at 80:40:26, the samples achieved an uniaxial compressive strength of up to 30.55 MPa without enhanced brittle post-processing. The failure characteristics exhibited significant axial tensile damage. Additionally, combining CT scanning technology demonstrated that the structural and mechanical properties of the samples can be effectively reproduced. Therefore, the 3D printing materials discussed in this paper provide a viable reference for accurately reconstructing high-strength and high-brittleness rock masses.

A Study on the Application Performance of High-Aspect-Ratio Nano-Ettringite in Photocurable Resin Composites.

In this study, the impact of the addition of high-aspect-ratio nano-ettringite to photocurable epoxy acrylate resin was explored. The nano-ettringite samples were modified using γ-Aminopropyltriethoxysilane (KH-550) and γ-methacryloxypropyl trimethoxy silane (KH-570). Then, 3 wt% or 6 wt% KH-550-modified, KH-570-modified, and unmodified nano-ettringite samples were dispersed into resin via ultrasonic treatment in conjunction with mechanical stirring. The grafting effects of nano-ettringite onto KH-550 or KH-570 were analyzed through scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric (TG) analysis. The results demonstrate that KH-550 and KH-570 have been successfully grafted onto the surface of nano-ettringite. In addition, this study also focuses on the variations of composite materials in the viscosity, shrinkage, tensile strength, and elongation at break. The results indicate that increased dosages of unmodified, KH-550-modified, and KH-570-modified nano-ettringite led to increased viscosity of the composite while reducing shrinkage. At the same dosage, the photocurable resin containing KH-570-modified nano-ettringite demonstrated a lower shrinkage and a higher tensile strength. From the analysis of tensile fracture surfaces, it was observed that compared to the KH-550 modified and unmodified variants, the KH-570 modified nano-ettringite exhibits superior dispersibility in photocurable epoxy acrylate resin. Notably, when the amount of KH-570-modified nano-ettringite was 3 wt%, the highest tensile strength of the composite was 64.61 MPa, representing a 72.57% increase compared to the blank sample. Furthermore, the incorporation of KH-570-modified nano-ettringite as a filler provides a new perspective for improving the performance of photocurable epoxy acrylate resin composites.

Effect of silanization of poly (urea-formaldehyde) microcapsules on the flexural strength and self-healing efficiency of an experimental self-healing dental resin composite (An in-vitro study)

ObjectivesThis study investigated the impact of using γ-methacryloxypropyl trimethoxy silane (MPS) for surface silanization of poly (urea-formaldehyde) (PUF) microcapsules which enclose a healing liquid of “triethylene glycol dimethacrylate (TEGDMA) and N,N dihydroxyethyl-p-toluidine (DHEPT)” on some mechanical properties of an experimental dental composite as well as its self-healing efficiency. MethodsSynthesis of PUF microcapsules was done via in situ polymerization, followed by silanization with MPS silane. Silanized and non-silanized microcapsules were incorporated into a composite containing 30% polymer matrix and 70% fillers at different weight percentages (0%, 5%, 7.5% and 10%). The composite strength and elastic modulus were evaluated by Flexural testing. Fracture toughness KIc and self-healing efficiency were assessed by utilizing the “single edge notched beam” method. ResultsFlexural strength of all groups containing silanized microcapsules was non-significantly different from control group without microcapsules. However, in contrast to control group, all groups containing non-silanized microcapsules displayed considerably decreased flexural strength. Adding silanized and non-silanized microcapsules didn't show a significant change in the KIc-virgin. The silanized microcapsules' groups achieved a self-healing efficiency of about 49–77% recovery in KIc-virgin compared to 38–69% for their non-silanized counterparts. SignificanceIn order to increase the interfacial adhesion with the polymer matrix, improve the mechanical properties, and increase the efficiency of self-healing of dental resin composite, PUF microcapsules were silanized for the first time in the dental field using MPS silane. This innovative silanized microcapsule-containing self-healing composite may hold promise for repairing the damage caused by restorative cracks and extending their service life.

Carbon Nitride Grafting Modification of Poly(lactic acid) to Maximize UV Protection and Mechanical Properties for Packaging Applications.

Due to their biobased nature and biodegradability, poly(lactic acid) (PLA) rich blends are promising for processing in the packaging industry. However, pure PLA is brittle and UV transparent, which limits its application, so the exploration of nanocomposites with improved interfacial interactions and UV absorbing properties is worthwhile. We therefore developed and optimized synthesis routes for well-designed nanocomposites based on a PLA matrix and graphitic carbon nitride (g-C3N4; CN) nanofillers. To enhance the interfacial interaction with the PLA matrix, a silane-coupling agent (γ-methacryloxypropyl trimethoxysilane, KH570) is chemically grafted onto the CN surface after controlled oxidation with nitric acid and hydrogen peroxide. Interestingly, only 1 wt % of CNO-KH570, as synthesized under mild conditions, is needed to significantly improve the UV absorption, blocking even a large part of both UV-C, UV-B, and UV-A outperforming the UV absorption performance of PLA and, for instance, polyethylene terephthalate (PET). The low nanofiller loading of 1 wt % also results in a higher ductility with an increase in elongation at break (+73%), maintaining the tensile modulus. The results on a joint optimization of UV protection and mechanical properties are supported by a broad range of experimental characterizations, including FTIR, XRD, DSC, DSEM, FETEM, XPS, FTIR, TGA, and BET N2 adsorption-desorption analysis.

Effect of ceramic primers with different chemical contents on the shear bond strength of CAD/CAM ceramics with resin cement after thermal ageing

BackgroundThis study evaluated the effect of ceramic primers containing 10-methacryloyloxydecyl phosphate (10-MDP) and γ-methacryloxypropyl trimethoxysilane (γ-MPTS) agents on the shear bond strength (SBS) of CAD/CAM ceramics with different chemical structures and resin cement.MethodsA total of 640 CAD/CAM ceramic specimens were obtained from Vita Mark II (VM), IPS E.max CAD (EM), Vita Suprinity (VS) and Vita Enamic (VE). The specimens were divided into two groups: etched with hydrofluoric acid (HF) and unetched. Each group was treated with a different ceramic primer (Clearfil Ceramic Primer Plus, G-Multi Primer and Monobond S), except for an untreated group (n = 10). After ceramic primers and resin cement were applied to each ceramic surface, half of the specimens were thermally aged at 10,000 cycles, 5–55 ± 1 °C, with a dwell time of 30 s. The SBS was tested with a universal testing machine at a 0.5 mm/min crosshead speed. Data were analysed by using statistical software (SPSS 20). Normal data distribution was checked with the Shapiro‒Wilk test. Three-way ANOVA was used to analyse the difference between the numeric data of the HF etched and thermally aged groups. A post hoc Tukey test was applied in the paired comparison of significant difference. The statistical significance level was accepted as p < 0.05.ResultsThe highest SBS values were obtained in the HF etched G-Multi primer applied nonaged EM group (28.3 ± 2.62 MPa), while the lowest values were obtained in the nonetched and thermally aged EM group that received no treatment (2.86 ± 0.04 Mpa). The SBS significantly increased in all specimens on which the ceramic primer was applied (p < 0.001). Thermal ageing had a significant negative effect on the SBS values in all groups (p < 0.001).ConclusionThe positive combined effects of the 10-MDP and γ-MPTS agents resulted in a significant increase in the bonding strength of the resin cement to the CAD/CAM ceramics. In addition, the increase in the amount of inorganic filler provided a favourable effect on durable adhesion.

Structural, optical, and mechanical characterization of PMMA-MXene composites functionalized with MEMO silane

Processing and characterization of PMMA-MXene composites were investigated. γ-Methacryloxypropyltrimethoxy (MEMO) silane was used to modify the surface of MXenes and improve the compatibility between MXenes and the polymer. The FTIR analysis revealed the formation of a chemical bond between MXene and MEMO silane, while the XPS analysis confirmed the presence of silicon in the functionalized MXene. PMMA composites with non-functionalized and functionalized MXene were prepared using a solution casting method. Tensile tests showed that, compared to neat PMMA, Young’s modulus increased in both composites by 22.1 and 27.6%, respectively. As a result of coupling between the PMMA matrix and the surface-modified MXenes, the tensile strength also increased by about 37%. In addition, optical spectroscopy showed higher absorption for the composite with surface-modified MXenes and short-lived fluorescence with emission intensity sensitive to the crumpling of functionalized MXene nanosheets.

Improving actuation strain and breakdown strength of natural rubber dielectric elastomers incorporated with AlN with silane grafting

In this study, dielectric elastomers offering intrinsically good integrated performances are achieved by introducing AlN particles grafted with γ-methacryloxypropyl trimethoxy silane (KH570). The C=C of KH570 participated in the vulcanization of NR, which could increase the dispersions and interfacial interactions. By incorporating 10 phr AlN-KH570 fillers, the dielectric and mechanical properties of the composite are increased compared with the pristine DEA, and the breakdown strength remains above 93.9 kV/mm. Correspondingly, the actuation strain of 10 phr AlN-KH570/NR composite is 7 times higher than that of pristine DEA under the same driving voltage. Consequently, the AlN particles developed here are promising candidates as dielectric in actuators, and their excellent electromechanical properties could be applied in future industrial applications of DEs.

Construction and Characterization of Polyolefin Elastomer Blends with Chemically Modified Hydrocarbon Resin as a Photovoltaic Module Encapsulant.

In this study, polyolefin elastomer (POE) was blended with a chemically modified hydrocarbon resin (m-HCR), which was modified through a simple radical grafting reaction using γ-methacryloxypropyl trimethoxy silane (MTS) as an adhesion promotor to the glass surface, to design an adhesion-enhanced polyolefin encapsulant material for photovoltaic modules. Its chemical modification was confirmed by 1H and 29Si NMR and FT-IR. Interestingly, the POE blends with the m-HCR showed that the melting peak temperature (Tm) was not changed. However, Tm shifted to lower values with increasing m-HCR content after crosslinking. Additionally, the mechanical properties did not significantly differ with increasing m-HCR content. Meanwhile, with increasing m-HCR content in the POE blend, the peel strength increased linearly without sacrificing their transmittance. The test photovoltaic modules comprising the crosslinked POE blend encapsulants showed little difference in the electrical performance after manufacturing. After 1000 h of damp-heat exposure, no significant power loss was observed.

Durable, strong, and flexible superhydrophobic N-TiO2 silicone composite aerogels with unique air–liquid–solid triphase photocatalytic properties

TiO2 nanoparticles are promising photocatalysts for the remediation of water pollution. However, the difficulty in recycling and low light absorption of powder TiO2 hinder their application in photocatalysis. Although some studies have attempted to address these problems by immobilizing TiO2, the application of traditional immobilized TiO2 in water environment is limited because of their unstable immobilization, poor mechanical strength, low light utilization, high electron-hole recombination,and unsatisfactory photocatalytic performance. In this study, flexible superhydrophobic Nitrogen-doped TiO2 (N-TiO2) silicone composite aerogels were achieved by copolymerization of γ-methacryloxypropyl trimethoxy silane (KH570)-grafted N-TiO2 with methyltrimethoxysilane and dimethoxydimethylsilane. These flexible composite aerogels possess improved mechanical strength and stable immobilization of N-TiO2. Moreover, an air–liquid–solid triphase photocatalytic interface was formed by the superhydrophobic surface of composite aerogel, solution and the air layer existed between them. This triphase photocatalytic interface enabled oxygen at the reaction interface to be directly and rapidly supplied from the air layer, thus photogenerated electrons from the photocatalyst surface can be effectively removed and the recombination of electron holes can be reduced. Besides, the flexible photocatalyst was molded into water grass shape and placed in a water channel to verify its photodegradation efficiency and durability under hydrodynamic conditions. Experimental results confirmed that the proposed flexible photocatalyst with a triphase catalytic interface has application prospects for the degradation of pollutants in water environment.

Facile and environmentally-friendly fabrication of robust composite film with superhydrophobicity and radiative cooling property

Endowing products used outdoors with superhydrophobicity and radiative cooling (RC) properties can decrease pollution caused by dust and heat accumulation resulting from the absorption of solar light, which is significant for prolonging life and maintaining the performance of these products. However, it is still challenging to find a facile and environmentally-friendly method to simultaneously achieve such two properties on the same film. Herein, we developed a composite film consisting of γ-methacryloxypropyl trimethoxy silane (KH-570), polydimethylsiloxane (PDMS), and SiO2 particles by a layered coating method, which exhibits strong sunlight reflectivity (>85%), high thermal-infrared emissivity (>0.95) and robust superhydrophobicity (162°). The as-obtained film achieves a sub-ambient temperature drop of 15 °C under direct sunlight. The preparation of the composite film can avoid using the reagents containing fluorine, which is environmentally friendly. The film can firmly adhere to different substrates such as glass and aluminum, which can widen the application scopes of this film. Furthermore, the composite film exhibits good durability during the wetting, outdoor daytime radiative cooling and mechanical abrasion tests, which is beneficial to the practical outdoor application of this film.

Improvement of UV-curable ink adhesion onto melamine faced board using dual silane treatments

ABSTRACT The application of UV digital inkjet printing onto melamine-faced board (MF) has attracted increasing attention as an efficient and environmentally benign surface decoration method. However, the interface bonding between UV coating and melamine-formaldehyde surface is weak, resulting in poor printing durability. In this study, the MF surface is grafted with 3-(triethoxysilyl) propyl isocyanate (ICPTES) via a urea cross-linking process, and then condensed with γ-methacryloxypropyl trimethoxy silane (KH570) to improve its compatibility with the polyacrylate-based UV ink. A combination of physical (surface polishing) and chemical (dual-silane treatments) activations of MF surface enhances its interface bonding strength with UV coating up to 2.24 MPa, 966.7% and 119.6% higher than those of the untreated and the conventional adhesion promotor treated surface, respectively. FTIR results confirm that effectual chemical bonds are established between MF surface and UV coating by the ICPTES and KH570 dual-silane treatments. SEM imaging shows that a seamless connection between MF and UV coating forms. Thus, MF surface modified by silane is a facile and effective strategy to enhance the adhesion of UV digital ink and this printing method shows enormous potentials in a wide range of applications.

The influences of silane coupling agents on the heat and moisture resistance of basalt fibre‐reinforced composites

Basalt fibre composite materials have shown good application prospects in electrical equipment, but their reliability can be affected by damp-heat ageing. In this work, the interface, mechanical, and electrical properties of basalt fibre composites treated with three coupling agents via damp-heat ageing were compared. Molecular simulations were conducted to reveal the damp-heat ageing mechanism of the composites. The results show that γ-aminopropyl triethoxy silane (KH-550) and γ-glycidoxy propyl trimethoxy silane (KH-560) perform better as coupling agents as they form bonds with the matrix resin, compared with γ-methacryloxy propyl trimethoxy silane (KH-570). After the damp-heat ageing treatment, the hydrolysis of the defects of the amino groups in the interface of the KH-550-treated sample can weaken its mechanical properties and insulation properties greatly. The interface layer of the KH-560-treated sample is mostly composed of carbon–oxygen single bonds and methylene groups with its interface structure more stable, which endows the sample with better stability of its mechanical and insulating properties. Therefore, KH-560 is a more suitable coupling agent for processing basalt fibres to be used in electrical equipment.

Synthesis and self-cleaning properties of superamphiphobic coatings based on burr-like copolymer particles

ABSTRACT Superhydrophobic and superoleophobic surfaces are widely used in many fields. Inspired by the structure of water strider legs, we proposed a simple method to construct a superamphiphobic surface based on burr-like KH-PS (copolymer of styrene and γ-Methacryloxypropyl trimethoxy silane) nanoparticles by soap-free emulsion polymerization and hydrolytic condensation reaction. In order to improve the film-forming properties and adhesion between coating and substrate, fluoromonomer-containing polysiloxane acrylate (PA) is designed and synthesized to bond burr-like nanoparticles. Then modify the fluorine-containing material on the surface of the burr-like particles to reduce the surface energy. The contact angles of the coating to water, diiodomethane, hexadecane, soybean oil, and rapeseed oil are 164.2° ± 1.5°, 155.3° ± 1.7°, 148.6° ± 1.9°, 152.7° ± 1.6°, and 153.5° ± 1.7°, respectively. The superamphiphobic coating exhibits excellent thermal stability, chemical stability, and self-cleaning performance. The microscopic roughness of coating constructed by organic polymer particles has broader application prospects on soft substrates such as fabrics.

Synthesis and application of magnetically recyclable nanoparticles as hydrate inhibitors

Current schemes dealing with hydrate blockage problems in gas pipelines suffer a high dosage of inhibitors and thus are associated with a significant risk of environmental damage. Overcoming these issues requires the development of novel recoverable inhibitors with persistent cycle performance. In this work, a new approach involving coating poly(vinylcaprolactam) (PVCap) and poly(vinylpyrrolidone) (PVP) onto the surface of γ-methacryloxypropyltrimethoxy silane (MPS)-modified Fe3O4 nanoparticles was proposed; this procedure enables the magnetic recovery of the inhibitory particles. It was found that the onset time of hydrate formation was extended 3 times compared to pure water with the help of the synthesized inhibitors showing better performance than commercial inhibitors. Excellent magnetic separation from sandy matrices in solution was achieved with a recovery efficiency of 86%. This was followed by a good cycle performance: the induction time remained still over 2 times longer than the pure water case after 5 cycles of recovery. The in-situ Raman spectra revealed that the recyclable inhibitors functioned through disturbing the construction of the large cages; a resulting mechanism was proposed with nanoparticles isolating the early hydrate patches preventing their further explosive bulk growth. In addition, the simple synthesis method makes it possible to coat various polymer inhibitors onto recovery particles. The results indicate that magnetically recovering the inhibitory particles and reusing them to hinder hydrate generation could be an alternative method to tackle the environmental and economic problems associated with current flow assurance procedures.

Development of highly durable superhydrophobic and UV-resistant wood by E-beam radiation curing

Developing a practical strategy to fabricate an anti-abrasion and durable superhydrophobic wood surface with ultraviolet (UV) resistance has great practical significance for expanding the application of natural wood. In this study, a robust superhydrophobic layer with a hierarchical micro/nano-roughness structure was modified on the wood surface through in-situ mineralization and polymerization using a simple sol–gel method along with efficient electron beam (EB) curing technology. Hydrophobic agent (polydimethylsiloxane, PDMS), and crosslinking monomer (γ-methacryloxypropyl trimethoxysilane, MAPS) form new covalent bonds between TiO2 particle layer and wood substrate after EB radiation, which endows robust superhydrophobicity and remarkable UV resistance on the wood surface. The as-prepared wood exhibited a water contact angle of approximately 165.7° and obvious repellency to many aqua-phase liquids (cola, strongly acidic, alkaline droplets etc.). Furthermore, the hierarchical micro/nano-protrusion structures remained unchanged and micro/nano particles aggregated tightly on the as-prepared wood surface under harsh external environments (sandpaper abrasion and, ultrasonic treatment), confirming the desirable anti-abrasion and mechanically durable performance of the superhydrophobic surface. After the 18-day UV accelerated weathering test, the TiO2 particle layer conspicuously retained the discoloration and maintained its exceptional repellency toward water. The biomimetic superhydrophobic wood with excellent mechanical durability and UV resistance reveals its potential application in the furniture and architecture fields.

Preparation and Properties of 3D Printing Light-Curable Resin Modified with Hyperbranched Polysiloxane.

A novel, hyperbranched polysiloxane (HBPSi) is successfully synthesized via hydrolysis using γ-methacryloxypropyl trimethoxysilane (A174) and deionized water, under catalyst-free conditions. Then, for the first time, the HBPSis are used to modify a 3D printing light-curing epoxy resin. Thermogravimetry results showed that the addition of HBPSi improved the heat resistance of the epoxy resin. Experimental results also show that the addition of HBPSi simultaneously improves tensile strength, elongation at break, and impact strength. In particular, a great increase in the toughness of 3D printing light-curing epoxy resin is observed, with 5 wt % HBPSi loading. These results indicate that the HBPSi containg OH– and Si–O–Si can be potentially effective at improving the performance of the 3D printing light-curing epoxy resin. This investigation suggests that the method proposed herein is a new approach to develop the performance of 3D printing light-curing epoxy resin for cutting-edge industries, especially those that simultaneously have outstanding thermal resistance and toughness.

Superhydrophobic self-floating TiO2-silicone composite aerogels and their air–liquid-solid triphase photocatalytic system

Semiconductor photocatalysis is as a promising method for water pollution remediation. However, the recycling and light capture of powder photocatalysts in traditional suspension systems are bottlenecks for their practical application in photocatalysis. Moreover, the large-scale application of traditional immobilized photocatalytic systems immersed in solution is limited due to the electron-hole recombination and slow reaction rate. Herein, we have successfully prepared superhydrophobic self-floating TiO2-silicone composite aerogels by condensation polymerization of γ-methacryloxypropyl trimethoxysilane (KH570) modified anatase TiO2and methyltriethoxysilane (MTES). The air–liquid-solid triphase photocatalytic system was constructed using the air layer formed by the superhydrophobic self-floating composite aerogel and the solution interface, which solved the above-mentioned limitation. The floating characteristics of the system effectively avoided the absorption of light by the solution, thereby significantly enhancing the light utilization of the catalyst. The air–liquid-solid interface allows oxygen to be quickly transported from the air to the reaction interface, and oxygen, which is a natural electron scavenger, can effectively remove photoelectrons from the catalyst surface and the recombination of electron-holes is minimized. The new self-floating photocatalyst with triphase catalytic system presented high practical application value for the degradation of suspended pollutants in a natural environment.

Intense shear induced caterpillar-like continuous hierarchical fiber enhanced poly(butylene succinate) biocomposite towards strong mechanical performance

Herein, we used intense shear to construct caterpillar-like continuous hierarchical fibers (CLCHF). This architecture was then modified with mussel inspired poly(dopamine) (PDA) and γ-methacryloxypropyl trimethoxy silane (KH570) in a one-step method. Finally, employing (PDA + KH570)@CLCHF and compounded with poly(butylene succinate) (PBS) ultrafine fiber, (PDA + KH570)@CLCHF/PBS biocomposite was manufactured by combining intense shear and thermal-compression method. In virtue of intense shear, CLCHF can be effectively produced with nanoscale fibrils from 2 nm to 28 nm and (PDA + KH570)@CLCHF and PBS ultrafine fibers displayed favorable homogenization in aqueous solution. More importantly, the interspace between (PDA + KH570)@CLCHF and PBS ultrafine fibers could be optimized to facilitate infiltration at high filler content in polymers. The results also showed that the PBS biocomposite with 30 wt% (PDA + KH570)@CLCHF displayed optimal mechanical performance. Its tensile strength, elastic modulus, flexural strength, flexural modulus and impact strength reached to 120.2 MPa, 6.4 GPa, 110.1 MPa, 4.0 GPa and 23.5 kJ/m2, respectively. It is noticeble that the tensile properties were superior to some previously reported PBS biocompoistes due to the ability of CLCHF to effectively hinder the aggregation of numerous microcracks and slow crack tip propagation. The (PDA + KH570)@CLCHF/PBS biocomposites reported here can be used as desirable substitutes for nondegradable composites due to its high value added and favorable mechanical performance, and may broaden the application prospect of PBS biocomposite.

Facile construction for new core-shell Z-scheme photocatalyst GO/AgI/Bi2O3 with enhanced visible-light photocatalytic activity

Heterojunction formation and morphology control have always been regarded as effective ways to improve the performance of visible-light-driven photocatalysts. In this study, a new facile strategy was applied to synthesize the Z-scheme GO/AgI/Bi2O3 heterojunction, where polyvinyl pyrrolidone (PVP) and γ-methacryloxypropyl trimethoxy silane (KH-570) were used to modulate the morphologies. Methyl orange and tetracycline hydrochloride were chosen as target contaminants to evaluate the photocatalytic properties of samples and the results revealed that 2% GO/AgI/Bi2O3 exhibited the best photocatalytic performance under visible-light irradiation. The enhanced photocatalytic activity can mainly attribute to Z-scheme heterojunction formed by the deposing of AgI and GO as well as the sufficient heterogeneous interfaces resulted from the improved morphology, which have effectively promoted the separation and transfer of electron-hole pairs. To deeply realize the enhanced performance of GO/AgI/Bi2O3 photocatalysts, the reaction kinetics, trapping experiments and photocatalytic mechanism were deduced.

Combined treatments of fiber surface etching/silane-coupling for enhanced mechanical strength of aramid fiber-reinforced rubber blends

This study sought to improve the interfacial bonding force between aramid fiber (AF) and a rubber matrix. We pretreated the aramid fiber with anhydrous calcium chloride (CaCl2) and sodium hydroxide (NaOH) solutions. We then performed a separate modification using two different methods, first, grafting the aramid fiber with silane coupling agent γ-Methacryloxypropyl trimethoxy silane (KH570) and secondly in situ formation of silica on the surface of aramid fiber. In addition, mechanical blending was adopted to prepare natural rubber/cis-1,4-polybutadiene rubber/aramid fiber (NR/BR/AF) composites. Finally, aramid fibers were characterized via Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electronic microscopy (SEM), then the mechanical properties of the corresponding composites analyzed. Results revealed that the synergistic action of anhydrous CaCl2 and NaOH solutions caused an increase in surface roughness and the contact area of the aramid fiber. The Sol-gel method allowed successful coating of the secondary modified aramid fiber surface with a layer of in situ-generated silica. Consequently, this improved surface reactivity of the fiber and the rubber matrix, thus promoting their combination. Moreover, we successfully grafted KH570 onto the surface of the aramid fiber through an oxygen-containing group on the surface of the pretreated aramid fiber. Tensile properties of AF composites exhibited a 31.9% increase after secondary modification with KH570 whereas their DIN abrasion performance increased by 16.2%. Notably, a significant improvement in interfacial adhesion was recorded in modified AF prepared NR/BR composites, which further improved the mechanical properties of NR/BR composites.