Silane Grafting Research Articles

Sulfur Free Crosslinking of EPDM Composites via Silane Grafting and Silica Incorporation.

This study aims at evaluating and developing an environmental-friendly and sulfur-free cured ethylene propylene diene monomer (EPDM) composites. Silane grafted EPDM (SiEPDM) composites incorporated with silica is prepared via a solvent-free, one-step reactive mixing process. The silane grafting and silica filler bonding are characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The mechanical properties of the developed composites are examined. The fracture morphology is observed using an environmental scanning electron microscopy. The rheology and thermomechanical properties are evaluated by using a rotational rheometer and dynamic mechanical analyzer. Notably, a robust bonding between silica and the grafted silane is established, yielding a crosslinking network within the composite structure. This phenomenon is substantiated by the observed gel efficiency and rheology behavior. Consequently, a pronounced augmentation of up to 75% in tensile strength and 29% in tear strength are observed in the optimized SiEPDM-silica composites, distinguishing them from their EPDM-silica counterparts. The introduction of paraffin oil contributes to enhanced processability; however, it is concomitant with a reduction in gel efficiency and associated mechanical properties. Furthermore, subsequent UV weathering test unveils that the SiEPDM-silica composites exhibit the highest levels of residual tensile strength and modulus, indicative of their exceptional UV stability.

Super-hydrophobic graphene-based high elastic sponge with superior photothermal effect for efficient cleaning of oil contamination

Oil spills are frequent and often accompanied by chemically corrosive and complex operating environments, so there is an urgent need for new absorbent materials that can absorb oil efficiently and with stable performance. Herein, we reported a reduced graphene oxide coated melamine sponge (F-rGO@MF) modified by silane grafting, which had excellent superhydrophobic/superoleophilic surface properties (WCA up to 157.7°), high absorption capacity (58.7–147.8 g/g) for a variety of oils, and could perform multiple absorption cycles. The separation efficiency of the oil/water mixture was as high as 99.32%, and the separation efficiency could still reach 97.48% after 80 separation cycles. The absorbent could also separate oil and water continuously by peristaltic pump. Besides, F-rGO@MF still retained floating and chemical stability under strong corrosive environment. More importantly, due to the photothermal property of rGO, the surface temperature of F-rGO@MF could rapidly rise to 101 °C under 1.0 kw/m2 light intensity for 225 s, which was contribute to the viscosity reduction of crude oil and absorbed 14.75 g of crude oil in 7 min, providing the possibility of absorbing high viscosity oil spills.

Bio-derived phosphorous-nitrogen-silicon decorated halloysite nanotube towards enhancing flame retardant, UV-blocking and mechanical properties of poly(lactic acid)

Developing flame retardant and UV-blocking polylactide (PLA) with reinforced mechanical properties is important but challenging. Herein, bio-derived phytic acid was decorated on halloysite nanotube though silane grafting, ring-opening reaction with melamine and then electrostatic interactions with phytic acid. The obtained phopsphorous-nitrogen-silicon decorated halloysite nanotube (PNSiHNT) was incorporated into PLA to prepare PLA composites. The surface modification significantly improved the compatibility between PNSiHNT and PLA, and the flame retardant, UV-shielding and mechanical properties of the composites were enhanced. At 5% mass loading, the peak heat release and total heat release were reduced by 18% and 12% compared to pure PLA, respectively, superior to most phytic acid-based flame retardants. The relevant mechanism analysis showed that PNSiHNT can restrain the emission of combustible volatiles and promote the formation of protective char layer. Moreover, the flame-retardant PLA showed excellent UV-shielding ability with an ultraviolet protection factor (UPF) value of around 120. Due to the reinforcing effect of PNSiHNT and the strong interfacial interactions between PNSiHNT and PLA matrix, the PLA/PNSiHNT showed 77% and 116% increase in tensile strength and elongation at break compared to the bulk PLA. This study provides a strategy for designing bio-derived organic/inorganic systems for enhancing flame retardant, UV-blocking and reinforced PLA.

Effects of functionalization and silane modification of hexagonal boron nitride on thermal/mechanical/morphological properties of silicon rubber nanocomposite

Hexagonal boron nitride (h-BN) nanoparticles could induce interesting properties to silicone rubber (SR) but, the weak filler-matrix interfacial interaction causes agglomeration of the nanoparticles and declines the performance of the nanocomposite. In this work, h-BN nanoparticles were surface modified using vinyltrimethoxysilane (VTMS) at different concentrations. Before silane modification, h-BN nanoparticles were hydroxylated using 5 molar sodium hydroxide. The nanoparticles were characterized to assess success of silane grafting. The pure and modified h-BN nanoparticles were applied at 1, 3 and 5 wt% to HTV silicon rubber (SR). The curing, thermal, mechanical and morphological properties and hydrophobicity of the nanocomposites were evaluated. The morphology of the SR nanocomposites was characterized using AFM and FE-SEM analysis. It was found that silane grafting on the h-BN nanoparticles improves crosslink density but declines curing rate index (CRI) of the SR nanocomposite (at 5 wt% loading content) by 0.7 (dN m) and 3.5%, respectively. It also increased water contact angle of the nanocomposites from 97.5° to 107°. The improved nanoparticle-rubber interfacial interactions caused better dispersion of h-BN nanoparticles in SR matrix (at 5 wt%) that enhanced the elongation at break, modulus at 300% and Tg of the SR nanocomposites.

Surface functionalization/silane modification of CeO2 nanoparticles and their influences on photocatalytic activity of acrylic films for methylene blue removal

In this study, the photocatalytic degradation of methylene blue (MB) as model organic pollutant by pure and silane modified CeO2 nanoparticles was assessed. The surface modification was performed using 3-aminopropyltriethoxysilane (APTES) at different silane concentrations. The nanoparticles were previously functionalized using hydrothermal process to increase silane grafting ratio. The grafting of silane molecules to the nanoparticles surface was confirmed using FTIR and XPS analysis. It was found that hydrothermal treatment increased the surface OH groups and silane grafting ratio by about 30 and 55 %, respectively. Surface modification of the functionalized CeO2 nanoparticles enhanced photocatalytic degradation of MB polluted wastewater up to 85.7 and 104 % compared to the pure nanoparticles under UV and solar lights, respectively. The pure and modified nanoparticles were applied at 1, 3 and 5 wt% to an acrylic latex. The prepared acrylic nanocomposite films were evaluated for photocatalytic degradation of MB stain and also for mechanical properties. It was found that silane modification of nanoparticles caused about 62 % decrement in the water contact angle (i.e. increment in hydrophobicity), 540 % improvement in the tensile strength and 18.6 times enhancement in the modulus of the acrylic film compared to the pure nano CeO2 containing acrylic film, respectively.

Silanization of functionalized PET fabric to improve PET-nitrile rubber (NBR) adhesion; effects of functionalization type and silane concentration

Surface modification could increase affinity of PET fibers to polymer matrix by changing the interfacial physical interactions to covalent bonds. In this research, surface modification of a superfine polyethylene terephthalate (PET) fabric was performed by bis(triethoxysilylpropyl)tetrasulfide (TESPT). The surface grafting was performed at different silane concentrations (i.e. 1, 5 and 10X). Before silanization, the fabrics were functionalized using photochemical method (i.e. irradiation of UV light in presence of glutaric acid peroxide (GAP)) and also hydrolysis by Sodium hydroxide (NaOH). Due to functionalization, carboxyl and hydroxyl groups were formed on the PET surface that made it ready to condense with hydrolyzed silane molecules. The fabrics were characterized using FTIR, TGA, FE-SEM, XPS analysis for evaluation of grafting performances. XPS analysis confirmed the presence of new peaks of Si and S after surface modification with TESPT. Comparing the results of TESPT-grafted functionalized PETs, it was found that the silane grafting content on PET surface is dependent not only to the silane concentration but also to the functionalization method. Finally, the influences of silane grafting on the functionalized PET fabrics to NBR adhesion were evaluated using H-pull and T-peel tests. The results showed that silane grafted-carboxylated PET fabric illustrated more adhesion to NBR than silane grafted-hydroxylated PET (i.e. 33 and 12% improvement in the pullout strength and T-peel adhesion, respectively).

Mechanical and thermal characteristics of steam‐exploded silane grafted Kigelia Pinnata fruit (KPF) fiber reinforced vinyl ester polymer composites

AbstractThe cellulose‐rich Kigelia pinnata aqueous fruit (KPF) fiber is a valuable natural biomass and has drawn attention as a renewable resource. Vinyl ester polymer matrix composites with better interfacial properties can have higher mechanical and energy dissipation properties. It can be obtained by the use of steam‐exploded silane‐grafted KP fibers with various fractions incorporated in the polymer matrix. KPF fiber grafting was maximized at 5% concentration after a steam explosion, removing hemicelluloses and lignin, thereby enriching a 23% crystallinity index (CI), leading to rich cellulose fiber. Steam explosion along with silane grafting increases the interfacial adhesion of the KPF fibers and the matrix through the interfacial bonding structure of Si–O–Si bonds, as confirmed by FTIR. A fiber with greater tensile strength was used to fabricate the vinyl ester composites. The highest tensile value of the steam‐exploded silane surface‐modified 30% KPF fiber‐reinforced composite was 125 MPa compared to the unmodified one due to increased stress distribution and restricted polymer chain movements. Compared to the untreated 30% KPF fruit fiber composite, steam‐exploded silane‐treated fiber showed a 12% higher impact energy due to faster load transfer, causing more impact energy absorption. A relatively higher interlaminar shear strength was shown for 30% treated KPF composites than for 30% untreated KPF composites. The steam‐exploded silane‐treated fiber (30%) composite shows the greatest thermal decomposition temperature of 399 °C because silane‐surface‐treated fibers contact the organo‐functional silane group in the polymer matrix. As a result, it obstructs polymer chain motions at higher temperatures, causing increased bonding strength.

Hydrophobic modification of a PVDF hollow fiber membrane by plasma activation and silane grafting for membrane distillation.

Polyvinylidene fluoride (PVDF) hollow fibers were hydrophobically modified using a simple and scalable method of plasma activation and silane grafting. The effects of plasma gas, applied voltage, activation time, silane type, and concentration were investigated according to the membrane hydrophobicity and direct contact membrane distillation (DCMD) performance. Two kinds of silane were used, including methyl trichloroalkyl silane (MTCS) and 1H,1H,2H,2H-perfluorooctane trichlorosilane silanes (PTCS). The membranes were characterized by techniques such as Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and contact angle. The contact angle of the pristine membrane was 88°, which increased to 112°-116° after modification. Meanwhile, the pore size and porosity decreased. In DCMD, the maximum rejection reached 99.95% by the MTCS-grafted membrane, while the flux decreased by 35% and 65% for the MTCS- and PTCS-grafted membranes, respectively. Treating humic acid-contained solution, the modified membrane showed steadier water flux and higher salt rejection than the pristine membrane, and 100% flux recovery was achieved by simple water flushing. This two-step method of plasma activation and silane grafting is very simple and effective to improve the hydrophobicity and DCMD performance of PVDF hollow fibers. However, further study on improving the water flux should be carried out.

Insights into boosting SiC membrane superhydrophobic-superoleophilic property and oil purification performance by hierarchical structure control

Engineering of superhydrophobic-superoleophilic (SHB-SOL) ceramic membrane surface with hierarchical structures remains challenging and the relation between physicochemical structure-dependent wettability and separation performance lacks investigation. Herein, SHB-SOL SiC ceramic membranes with different hierarchical micro-nano structures were fabricated by ZnO nanoflower (NF) deposition and silane grafting. Three SiC ceramic membranes with different pore sizes were purposefully used as the pristine, these membranes displayed similar geometric structures in different scales. The modified SiC membrane surface becomes stronger in SHB-SOL property as the pore size decreases and the optimal membrane possessing the lowest pore size presented a water contact angle of 172.46° and a water sliding angle of 5°. When used for pure oil or oily mixture separation, all the SHB-SOL SiC membranes exhibited enhanced oil fluxes compared with their pristine forms. At a pressure of 0.5 bar, the optimal membrane could completely reject water droplets and graphite solids (D50 =4.8 µm) for the oil-water-solid mixture containing 0.05 wt% water and 0.05 wt% graphite, showing a stable oil (hexane) flux of 1383.8 L·m−2·h−1. This work also reveals the effects of the hierarchical structures on the SHB-SOL property formation and the resulting antifouling mechanism, which offers novel insights into boosting ceramic membranes with desired surface wettability for enhanced separation performance.

Vapor-phase grafting of functional silanes on atomic layer deposited Al2O3

Fundamental studies are needed to advance our understanding of selective adsorption in aqueous environments and develop more effective sorbents and filters for water treatment. Vapor-phase grafting of functional silanes is an effective method to prepare well-defined surfaces to study selective adsorption. In this investigation, we perform vapor phase grafting of five different silane compounds on aluminum oxide (Al2O3) surfaces prepared by atomic layer deposition. These silane compounds have the general formula L3Si–C3H6–X where the ligand, L, controls the reactivity with the hydroxylated Al2O3 surface and the functional moiety, X, dictates the surface properties of the grafted layer. We study the grafting process using in situ Fourier transform infrared spectroscopy and ex situ x-ray photoelectron spectroscopy measurements, and we characterize the surfaces using scanning electron microscopy, atomic force microscopy, and water contact angle measurements. We found that the structure and density of grafted aminosilanes are influenced by their chemical reactivity and steric constraints around the silicon atom as well as by the nature of the anchoring functional groups. Methyl substituted aminosilanes yielded more hydrophobic surfaces with a higher surface density at higher grafting temperatures. Thiol and nitrile terminated silanes were also studied and compared to the aminosilane terminated surfaces. Uniform monolayer coatings were observed for ethoxy-based silanes, but chlorosilanes exhibited nonuniform coatings as verified by atomic force microscopy measurements.

Surface modification of carbon nanotubes by a bifunctional amine silane; effects on physical/mechanical/thermal properties of epoxy nanocomposite

Weak interfacial interactions between MWCNTs and epoxy matrix causes agglomeration of the nanotubes and declines in the nanocomposite performances. In this study, MWCNTs were surface modified by a bifunctional amino silane (i.e. Bis (3-triethoxysilylpropyl)amine) at different concentrations. The nanotubes were previously functionalized through acid oxidation to increase silane grafting ratio. The pure, functionalized and silanized carbon nanotubes were characterized to assess the success of silane grafting. The pure and modified nanotubes were applied at different contents (0.5, 1 and 2 wt%) to epoxy resin. The tensile, flexural and compressive properties of the nanocomposites were evaluated. The nanocomposites were also characterized using water contact angle test, DSC, DMTA and FE-SEM/EDS analysis. It was observed that silanization of nanotubes caused considerable increment (32°) in the water contact angle of epoxy films. The results showed that incorporating the pure nanotubes (at 0.5 wt%) to epoxy resin enhanced the mechanical strengths but decreased the modulus of the epoxy sample. It was found that incorporating 0.5 wt% of modified MWCNT into epoxy binder caused 33, 53 and 40 % improvement in the tensile, flexural and compressive strengths and 56, 85 and 110 % increment in the tensile, flexural and compressive modulus compared to the pure MWCNT containing nanocomposite. The modified MWCNTs participated in curing of epoxy resin through reaction of silane amide groups with resin epoxide groups that this increased enthalpy of curing up to 25 %.

Al2O3 decorated with polyhedral silsesquioxane units: An unconventional filler system for upgrading thermal conductivity and mechanical properties of rubber composites

The present study reports on the development and exploitation of an original filler system, based on alumina nanoparticles (NPs) and polyhedral silsesquioxane (POSS) units, namely Al2O3@POSS, where the remarkable compatibilization and thermomechanical features imparted by the silsesquioxane cage units “makes an alliance” with the enhanced thermal conductivity of Al2O3 NPs. The target is to supply rubber nanocomposites with improved heat transport and mechanical properties potentially applicable in tires formulation.The hybrid filler was prepared by a double-step approach consisting of a first silanization of Al2O3 with a methacrylate silane and subsequent grafting of OctaMethacrylPOSS through a radical reaction mediated by dicumyl peroxide as radical initiator. The material was characterized in depth in terms of structure, surface, and morphology and then used for producing, by solvent-casting technique, polybutadiene composites. The idea is to supply and test a model alumina-rubber based system which allows to better unveil the role played by the silsesquioxane units, thanks to the absence of other components (i.e. rubber polymers, vulcanization curatives and filler) usually included in real rubber formulations for tires.The comprehensive thermomechanical and morphological characterization of the nanocomposites highlighted the key role played by POSS units decorating the alumina surface, which assure both the compatibility between filler and polymer host, and an homogeneous distribution and continuous networking of the alumina NPs. This positively influences not only the heat transport, providing thermal conductive pathways that raise the thermal diffusivity even at low filler loadings (+60–70% with respect to composite enclosing bare alumina at a concentration of 15–10 v/v %) but also the storage modulus, paving the way toward a potential exploitation of Al2O3@POSS hybrid filler in large-scale formulations of rubber composites, namely those employed for tires.

Study on Water Absorption Characteristics, Various Chemical Treatments, and Applications of Biological Fiber-Reinforced Polymer Matrix Composites

This study presents an extensive survey of the many surface treatments that may be given to natural fibers for use in advanced composites. When put into reality, the primary disadvantages of working through biological fibers are the increased level of moisture intake that natural fibers possess as well as their low dimensional stability. The fundamental purpose of applying surface treatments to natural fibers is to optimize the bonding strength as well as the pressure transferability in composites made of biological natural fibers. Natural fiber-strengthened polymer composites (NFPC) have overall mechanical qualities that are strongly dependent on the morphological, aspect ratio, hydrophilic propensity, and high stiffness of the natural fibers that are employed in the composite. Cellulosic fibers are being studied for their effects both before and after being used as reinforcements for thermoset and thermoplastic polymers. Some of the chemicals utilized in treatments include alkalis, silane, acetyl, benzoylation, acrylation and polyamide grafting, maleated linking agents, ammonium nitrate, peroxide, phenoxy, stearic acid, potassium chalcopyrite, triazine, synthetic derivatives of fatty acids (oleoyl chloride), and fungi. After chemical treatment, composites made from organic fibers are stronger and more dimensionally stable than the untreated sample.

Preparation of dense modified nanosilica superhydrophilic coatings on aluminum alloy surfaces by adjusting amino groups

In this work, a uniform superhydrophilic coating was prepared by grafting N-(2-aminoethyl)-3-aminopropyltriethoxysilane oligomers(AEAOS) onto nanosilica by using silane coupling agent modification and coated on the surface of aluminum alloys to reduce water droplet generation. The grafting and dispersibility of modified nanosilica and aminosilane oligomers were characterised using Fourier transform infrared (FTIR) and dynamic light scattering (DLS). The surface state, composition, and roughness of the coatings were characterised with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and optical profilometer. The hydroxyl and organic content of modified nanosilica was analyzed by Thermogravimetric Analysis (TGA). The compactness of the coating film is analyzed by an electrochemical impedance. The hydrophilicity and adhesion of the coating films were evaluated by contact angle and adhesion testing. By adjusting the concentration of amino groups in the nanosilica sol, the results show that the amino groups promote the silane grafting on the surface of nanosilica. The 10% addition of AEAOS gives the modified silica film a contact angle of <5° with superhydrophilic properties. The polarization resistance of the superhydrophilic coating film is about 10 times higher than that of the original aluminum alloy. The surface of the coated films is homogeneous and dense, showing high resistance to polarization and good corrosion resistance.

Toward a method of understanding the complexation of rare earth element by functionalized organosilanes in aqueous media

In the context of rare earth element extraction using solid-liquid process, hybrid materials having specific functional group were largely studied. However, there is a lack of in situ characterization method to understand how the functional group behaves when interacts with the rare earth element. Here, we propose a new experimental method to understand the interaction between immobilized functional group and REE in aqueous media using a well-characterized model system coupled to surface analyses. Model system was prepared by grafting diglycolamide functionalized silane on planar silica substrate. In order to have a clear description of the morphology and the structure of the model system, the silane grafting process was characterized using contact angle measurement, X-Ray Reflectivity, peak force measurements by Atomic Force Microscopy and in situ analysis by Fourier Transformed Infrared Spectroscopy in Attenuated Total Reflection. Afterwards, the behavior of the grafted molecules was investigated in neodymium aqueous solution at various pH by in situ infrared spectroscopy and hard X-ray reflectivity characterizations. Here, we highlight that the complexation of Nd3+ by the diglycolamide function is correlated with its dehydration and a modification of the molecule configuration.

Investigation of grafting silane coupling agents on superhydrophobicity of carbonyl iron/SiO2 particles for efficient oil/water mixture and emulsion separation

The present study demonstrated the wettability properties of grafting silane coupling agents on carbonyl iron (CI)/SiO2 particles for efficient oil/water mixture and emulsion separation. CI particles were first reacted with Tetraethoxysilane (TEOS) to create a magnetic component. Then, CI/SiO2 particles were altered by 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS) and Hexamethyldisilazane (HDMS) to create magnetic superhydrophobic/superoleophilic, recyclable, and reusable sorbent powders. The water contact angle (WCA) values of the as-prepared particles, CI, CI/SiO2, CI/SiO2@FAS, and CI/SiO2@HMDS, were 5.4° ± 1.3°, 6.4° ± 1.4°, 151.9° ± 2.1°, and 170.1° ± 1.1°, respectively. In addition, the oil contact angles (OCAs) of a variety of oils were found to be equivalent to 0°. Hence, superhydrophobic/superoleophilic particles for kind of different oils were shown sorption capacities of 1.7–3.1 g/g and 2.5–4.3 g/g for CI/SiO2@FAS, and CI/SiO2@HMDS, respectively. Besides, for 1%w/w hexane/water emulsion separation efficiency higher than 99%, the lowest mass was obtained at 50 and 200 mg for CI/SiO2@HDMS and CI/SiO2@HDMS, respectively, suggesting a new effective material for separating tiny oil droplets. Also, the reusability and chemical durability of the superhydrophobic samples made them a prime candidate for use in different harsh conditions.

Improving the Mechanical/Anticorrosive Properties of a Nitrile Rubber-Based Adhesive Filled with Cerium Oxide Nanoparticles Using a Two-Step Surface Modification Method.

To prepare a nanocomposite adhesive based on nitrile rubber (NBR) with excellent mechanical/anticorrosion properties, cerium oxide (CeO2) nanoparticles were grafted with bis-[3-(triethoxysilyl)propyl]tetrasulfide silane (TESPT) at different concentrations (i.e., 1, 5, 10, and 20 times the stoichiometric content). The surface-modified nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), ζ-potential, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FE-SEM) techniques. The results showed that the steaming process resulted in an increase in the grafting ratio (R g) by 2.35 times. Pure and modified cerium oxide nanoparticles were added at 1.5, 4.5, and 7.5 wt % to a mixture of a phenolic resin and NBR compound to prepare adhesive samples. The prepared adhesives were evaluated for curing behavior and thermomechanical properties. The morphology of the adhesives was also characterized using SEM analysis. The bonding of adhesives to steel plates was measured by a cathodic disbonding test. The adhesive-coated steel plates were evaluated for anticorrosion performances using a salt spray test. It was found that surface-modified hydrothermally steamed CeO2 nanoparticles that had the highest silane grafting ratio enhanced the anticorrosion properties and cathodic disbonding of NBR-based adhesives. The curing rate index (CRI) and crosslinking of the NBR compound were enhanced using the modified and steamed nanoparticles. This also improved the interfacial interactions between rubber chains and nanoparticle surface, resulting in a 6 °C increase in the glass-transition temperature (T g) of NBR compared to the pristine rubber.

Design and fabrication of nano textured superhydrophobic and anti-corrosive silane-grafted ZnO/bio-based polyurethane bilayer coating

Superhydrophobic polymer coatings are receiving special attention for industrial applications due to their multifunctionality behaviour. The advancement in nanotechnology has made it easier to design and fabricate nano-textured superhydrophobic coating on metal surfaces, even though adhesion and durability still remain a challenge. Therefore, the present study focuses on a novel bilayer coating approach for fabricating thermally stable, abrasion tolerant, multi-functional, superhydrophobic surface coating through the chemical bonding at the interface of hydroxy terminated polydimethylsiloxane modified cardanol-based polyurethane and silane grafted ZnO nanoparticles. The silane grafting to the ZnO surface has been confirmed by FT-IR, EDX, and XPS analysis. In addition, the change in crystallinity of unmodified and modified ZnO-based HTPDMS-CPU have been studied using XRD analysis. The superhydrophobic surface coating showed a high contact angle of 151° and contact angle hysteresis of 7° which got reduced after 10 cycles of abrasion to 133° and 12°, respectively. The silane groups at the surface allow ZnO to disperse uniformly and get exposed through the polymer coating while forming the micro/nano scale morphology. Furthermore, the anticorrosion parameters of the superhydrophobic bilayer coating showed corrosion current density (Icorr) value of order 10−9 (A.cm2) and corrosion potential (Ecorr) value of −0.351 (V) with inhibition efficiency (ƞ) of 99.5 % on mild steel. Thus, the superhydrophobicity, along with the excellent anticorrosion properties of this bilayer coating with a strong interface, chemical resistance and thermal stability elaborates its applicability in various fields.

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.

Secondary silane grafting on aramid fibers improves the interfacial bonding performance in textile composite materials

To improve the chemical and physical surface features of aramid fibers and the bonding quality at the interface, carbon nanotubes, dopamine and silane coupling reagent KH560 were used to modify the surface of aramid fibers. The fiber surface was characterized by FTIR, XPS, SEM and AFM. The single-fiber specific strength, surface roughness, wettability and interfacial shear strength of the modified fiber were quantified. Finally, the uniaxial tensile behaviour of the textile composite laminate with the modified fibers was tested. The experimental results show that: after the grafting of silane coupling reagent as a second modification step, the amount of oxygen-containing groups on the surface of aramid fibers, and the surface roughness, and the ability to impregnate resin are further improved. The single-fiber specific strength, the interfacial shear strength by fiber pull-out tests, and the tensile strength of the laminate are increased by 21.62%, 73.57%, and 51.60%, respectively. This work demonstrates a general surface modification strategy working for diverse types of fibers, synthetic or natural. The present findings help to develop a broad range of high-performance textile composites to address long-term challenges in structural engineering.