Effect Of Coupling Agent Research Articles

Surface modification strategies for an improved interfacial compatibility between LLZO and a polymer substrate for applications in high-performance solid-state Li-metal batteries

The interfacial compatibility between inorganic powder and polymeric matrix is one of the most important key factors for the applications of polymer ceramic composite electrolytes (PCCEs). In the present study, a surface modification strategy has been proposed by using three different terminating groups of silane coupling agents in the modification of the interfacial compatibility between LLZO and PEO in PEO/LLZO composite electrolyte. Experiments and density functional theory (DFT) calculations have been performed in studying the effect of different silane coupling agents on interfacial properties. Especially, the interface compatibility is found to be improved when using amino-terminated silane coupling agent KH550, which is due to hydrogen bond interactions between amino groups and PEO. In addition, the mechanical strength and conductivity are significantly increased by increasing the interaction energy and by decreasing the crystallinity, and the values of 1.39 MPa and 0.22 mS cm−1 at 30 °C are then successfully achieved. As a result, the solid-state LiFePO4|PCCE|Li battery demonstrates a high discharge specific capacity of 157 mAh g−1 at 60 °C and 1C. And it has a cycle capacity decay rate of only 0.034 % for 380 cycles. These results pave the way for future developments of high-performance PCCEs.

Effect of Silane Coupling Agent Treatment of Aggregates on Mortar Workability, Strength and Interfacial Microscopic Properties

In this study, 3-aminopropyltriethoxysilane (KH550) and vinyltrimethoxysilane (KH171) were used to modify aggregates and prepare aggregates with different surface wettability. The effect of silane coupling agents on aggregate surface properties was characterized through FT-IR, XPS, contact angles and aggregate water absorption. The influence of the aggregate’s surface wettability on the interface properties was discussed using MIP, SEM, BSE and nanoindentation, and then the influence mechanism of the interface microscopic properties on the macro-properties of mortar was revealed. The results showed that the type of silane has an intense impact on the surface properties of aggregates. KH550-modified aggregates increased the contact angle from 23.6° to 59°, while KH171-modified aggregates increased it from 23.6° to 91.6°. Silane-modified aggregates reduced the surface hydrophilicity, thereby reducing the water absorption and improving the mortar’s workability. However, KH550-modified aggregates exhibited a more effective enhancement of the mortar’s mechanical properties. Specifically, KH550-modified aggregates reduced the aggregate’s surface hydrophilicity, consequently alleviating the interfacial edge effect. This led to a 10% increase in the compressive strength of the mortar, an 11.6% reduction in the porosity, an 8.4% decrease in the interfacial porosity, and a 42.3% increase in the elastic modulus of the ITZ. Meanwhile, the cement matrix obtained a greater amount of water for cement hydration, resulting in an increased degree of hydration and an 18.5% increase in the elastic modulus of the cement matrix. The improvement in the ITZ between the modified aggregates and the cement matrix is considered to be one of the fundamental reasons for the enhancement of the mortar’s performance.

Effect of functionalization on thermal conductivity of hexagonal boron nitride/epoxy composites

Electronic equipment generates a significant amount of heat during operation with the trend of integrated circuit chips and electronic components towards miniaturization and multi-functionality. Consequently, guaranteeing safe and dependable functioning while appropriately dispersing heat has become a critical challenge in the development of the microelectronics sector. The emergence of thermal interface materials (TIMs) with high thermal conductivity can effectively address this issue. In this study, simulations and experiments were used to investigate the effects of functional groups, including hydroxyl (-OH), dopamine (DA) and silane coupling agent (KH550), and their grafting ratios on the thermal conductivity of hexagonal boron nitride/epoxy (h-BN/EP) composites. The interface thermal conduction results demonstrated that the modification of functional groups with a higher grafting ratio exhibited a larger enhancement, and KH550 outperformed DA and -OH in terms of the enhancing effect. Moreover, according to the effective medium theory (EMT), the simulated thermal conductivity of BN-KH550/EP composite (2 % grafting ratio of KH550, 10 vol% filling ratio of BN) was 0.692 W·m−1·K−1, 224.9% higher than that of pure epoxy resin. Additionally, the experimentally measured thermal conductivity was 0.703 W·m−1·K−1, showing good agreement with the simulation result and indicating EMT's accurate prediction for the h-BN/EP composites.

Multi-scale analysis of the synergistic strengthening effect of silane coupling agent on PVA and cement interface

Conventional polyvinyl alcohol (PVA) cementitious composites are susceptible to macroscopic cracking when subjected to reduced compressive strength, diminished toughness, tensile impact and other external loads. In order to address these issues, this study investigates the mechanism of the modifier's influence by modifying PVA fibers with a silane coupling agent (KH560) through experimental studies and molecular dynamics simulations for multiscale computational analyses. Macro test results showed that the mechanical properties of PVA fiber concrete were significantly improved after silane coupling agent modified PVA fiber. The microscopic test results showed that the SCA-modified polymer film acted as a bridging ligament in the interfacial transition zone, effectively prevented crack extension, and enhanced the interfacial adhesion between the organic components of the PVA fibers and the cement matrix. Nanoscale molecular dynamics simulations showed that the hydrated calcium silicate exhibited a stable skeletal structure, while the introduction of SCA expanded the hydrogen bonding interactions at the interface, thus enhancing its stability.

A combination of experimental and theoretical approaches on SSBR/BR compounds reinforced by hybrid nano‐silica/carbon black: Mechanical and rheological properties

AbstractIn modern formulations for green tire treads, nano‐silica combined with silane coupling agents has recently partially replaced carbon black (CB) to improve the well‐known “magic triangle” of tire tread compounding. However, achieving adequate levels of CB in formulations is still a challenge. In this study, the effect of nano‐silica/CB hybrid reinforcements and silane coupling agents on rubber compound prepared by melt blending method was investigated. Microstructure, swelling, mechanical and rheological properties of highly filled SSBR/BR‐based compounds were investigated. The results showed that with the increase of CB content in SSBR/BR/TESPT/nano‐silica, the properties pass an optimum point. Various properties were confirmed by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) images. Estimation of the properties of tire tread compounds is inevitable due to the high cost of the components and the time and energy savings. For this purpose, different theoretical models were used. The Bergstrom‐Boyce, Ogden‐Roxburgh and Mooney‐Rivlin models were used to study the mechanical properties and the Herschel‐Bulkley, Power law and Carreau–Yasuda theories were used for the rheological properties. Among the theoretical models used, the Bergstrom‐Boyce model showed better correlation with the experimental data than other models.Highlights Compounds based on SSBR/BR rubber blends were prepared by the melt blending method. The effect of hybrid reinforcements and silane coupling agent as compatibilizer was studied. The microstructure, mechanical behavior, thermal and rheological properties of the compounds were investigated. The improved dispersion of the reinforcements in the SSBR/BR matrix was confirmed by microstructure analyses. Various theoretical models were applied to validate the experimental mechanical and rheological results.

Effect of Different Silane Coupling Agents on Properties of Waste Corrugated Paper Fiber/Polylactic Acid Composites.

The surface of plant fibers was modified by silane coupling agents to prepare plant fiber/polylactic acid (PLA) composites, which can improve the dispersion, adhesion, and compatibility between the plant fibers and the PLA matrix. In this work, three silane coupling agents (KH550, KH560, and KH570) with different molecular structures were used to modify the surface of waste corrugated paper fibers (WFs), and dichloromethane was used as the solvent to prepare the WF/PLA composites. The effects of different silane coupling agents on the microstructure, mechanical properties, thermal decomposition, and crystallization properties of the composites were studied. The mechanical properties of the composites treated with 4 wt% KH560 were the best. Silane coupling agents can slightly improve the melting temperature of the composites, and WFs can promote the crystallization of PLA. The modification of WFs by silane coupling agents can increase the decomposition temperature of the WF/PLA composites. The content and type of silane coupling agent directly affected the mechanical properties of the WF/PLA composites. The interfacial compatibility between the WFs and PLA can be improved by using a silane coupling agent, which can further enhance the mechanical properties of WF/PLA composites. This provides a research basis for the further improvement of the performance of plant fiber/PLA composites.

Enhancing adhesion strength via synergic effect of atmospheric pressure plasma and silane coupling agent

To facilitate the widespread use of carbon fiber reinforced thermoplastic polymer (CFRTP), enhancing its adhesion strength with other materials is crucial. In this study, we investigated the synergic effect and underlying mechanism of atmospheric pressure plasma and silane coupling agent on the adhesion improvement of CFRTP. The plasma/mercapto-silane-treated CFRTP demonstrated a remarkable 282% increase in adhesion strength compared to untreated CFRTP. Our post-fracture analysis revealed that the weakest CFRTP/adhesive interface was fortified, resulting in a shift in the failure mode from adhesive to substrate. Equipment analyses indicated that plasma and silane coupling agent contributed to the formation of C-O and Si-O-Si linkages, respectively. The application of both treatments led to the creation of a macro-network at the CFRTP/adhesive interface through both linkages, which resulted in a much more substantial increase in adhesion strength than either treatment alone. Lastly, we propose guidelines for enhancing the adhesion strength of CFRTP by elucidating the dependence of the synergic or antagonistic effect on the organofunctional group in silane coupling agent.

Effect of silane coupling agent on the ultraviolet weathering behavior of polylactic acid based composites

Polylactic acid (PLA) is a promising material due to its biodegradability and compatibility. However, the limited resistance to ultraviolet (UV) degradation of PLA composites hinders their use in automotive interior materials. In our previous work, we successfully prepared 3D printed filaments by combining KH550-treated micro-nano rice husk (MNRH) fibers with KH570-treated PLA, which exhibited favorable performance. This study aimed to investigate the effects of silane coupling agents, MNRH, and accelerated UV weathering time on the photodegradation behavior of 3D printed PLA-matrix composites reinforced with MNRH. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) were utilized to characterize the 3D printed PLA-matrix composites. Furthermore, an exponential equation between tensile strength and UV weathering time was established, providing theoretical guidance for predicting the service life of automotive interior materials based on PLA composites. The morphological characterization experimental results indicate that with prolonged UV aging time, both PLA and RH6-KH550/KH570 composite materials transitioned from transparency to translucency. This transition can be attributed to the rupture of polylactic acid molecular chains and chemical bonds during the UV aging process. FTIR test results revealed the formation of carboxylic acid in the composite, and the reduction of C = O absorption intensity indicated that MNRH and silane coupling agents exhibited a stabilizing effect on the UV durability of the RH6-KH550/KH570 composite. TGA and DSC results indicated that KH550 and KH570 delayed the photodegradation rate of PLA-matrix composites.

Immediate and Late Repair of Microhybrid Resin Composites: Effect of Silane Coupling Agent, Universal Adhesives and Photo Polymerization.

This study investigated the effect of silane coupling agent and universal adhesive application on repair bond strength of resin-based composite after bur grinding. Microhybrid resin composite (Charisma Smart) blocks (N=80; 8x8x4 mm3) were prepared, aged (37°C; 1 month), roughened, etched and randomly divided into two groups. Silane was applied to half of the groups (Porcelain Primer, Bisco), before one of the following universal primers/adhesives was applied: a) Scotchbond Universal (3M), b) All-Bond Universal (Bisco), c) G-Premio Bond (GC), and d) Clearfil SE Bond (Kuraray). In each adhesive group half of the group was photo-polymerized. The blocks were repaired with the same size resin composite and segmented into beams. Half of the beams were subjected to micro-tensile bond test (1 mm/min), while the other half was aged (37°C; 6 months) prior to testing. Failure modes were analyzed using Scanning Electron Microscopy (SEM). Data were analyzed using repeated measures of ANOVA, Tukey's post-hoc, and paired t-tests (alpha=0.05). The silane application did not affect the repair bond strength regardless of photo-polymerization of the adhesive resin. The repair bond strength decreased significantly after 6 months when adhesive resin was not photopolymerized (p⟨0.05). Photo-polymerizing universal adhesives might ensure higher repair bond strength and its maintenance after aging.

Effect of Different Silane Coupling Agents on the Bond Strength between Hydrogen Peroxide-Etched Epoxy-Based- Fiber-Reinforced Post and Composite Resin Core.

The aim of the study was to evaluate the effect of various silane coupling agents on the micro-push-out bond strength between a hydrogen peroxide-etched epoxy-based fiber-reinforced post and composite resin core. Seventy-five cross-linked epoxy-based fiber-reinforced posts were etched with 24% hydrogen peroxide for 10 min. Then they were divided into five groups according to various silane coupling agents and bonded to a composite core. A Universal Testing Machine was utilized to evaluate the push-out bond strength. In addition, all groups' modes of failure were assessed. The push-out bond strength data in MPa were analyzed using ANOVA and a Tukey HSD post hoc test to reveal any difference between the groups. Results revealed that the application of a two-bottle silane coupling agent exhibited the highest bond strength, while the application of a one-bottle silane coupling agent demonstrated the lowest bond strength for a hydrogen peroxide-etched fiber post bonded to a composite core material, which was statistically significant (p < 0.05). The strongest association with the highest bond strength was found with the two-bottle silane coupling agent when compared to the one-bottle. The study highlighted that the application of a silane-coupling agent may affect the bond strength between composite and epoxy-based fiber-reinforced posts.

Research on Properties of PBAT/CaCO3 Composite Films Modified with Titanate Coupling Agent.

High cost, low crystallinity, and low-melt strength limit the market application of the biodegradable material poly (butylene adipate-co-terephthalate) (PBAT), which has become a major obstacle to the promotion of PBAT products. Herein, with PBAT as resin matrix and calcium carbonate (CaCO3) as filler, PBAT/CaCO3 composite films were designed and prepared with a twin-screw extruder and single-screw extrusion blow-molding machine designed, and the effects of particle size (1250 mesh, 2000 mesh), particle content (0-36%) and titanate coupling agent (TC) surface modification of CaCO3 on the properties of PBAT/CaCO3 composite film were investigated. The results showed that the size and content of CaCO3 particles had a significant effect on the tensile properties of the composites. The addition of unmodified CaCO3 decreased the tensile properties of the composites by more than 30%. TC-modified CaCO3 improved the overall performance of PBAT/CaCO3 composite films. The thermal analysis showed that the addition of titanate coupling agent 201 (TC-2) increased the decomposition temperature of CaCO3 from 533.9 °C to 566.1 °C, thereby enhancing the thermal stability of the material. Due to the heterogeneous nucleation of CaCO3, the addition of modified CaCO3 raised the crystallization temperature of the film from 97.51 °C to 99.67 °C and increased the degree of crystallization from 7.09% to 14.83%. The tensile property test results showed that the film reached the maximum tensile strength of 20.55 MPa with the addition of TC-2 at 1%. The results of contact angle, water absorption, and water vapor transmission performance tests showed that TC-2 modified CaCO3 increased the water contact angle of the composite film from 85.7° to 94.6° and decreased the water absorption from 13% to 1%. When the additional amount of TC-2 was 1%, the water vapor transmission rate of the composites was reduced by 27.99%, and the water vapor permeability coefficient was reduced by 43.19%.

The Synergistic Effects of Aminosilane Coupling Agent on the Adhesion Performance of Silane Primer for Silicone Resin Thermal Protection Coating.

As a bridge between the coating and the substrate, the primer has a direct impact on the adhesion performance of silicone resin thermal protection coating. In this paper, the synergistic effects of an aminosilane coupling agent on the adhesion performance of silane primer were investigated. The results show that silane primer containing N-aminoethyl-3-aminopropylmethyl-dimethoxysilane (HD-103) formed a continuous and uniform film on the surface of the substrate. Two amino groups of HD-103 were conducive to moderate and uniform hydrolysis of the silane primer system, and the introduction of dimethoxy groups was more conducive to the improvement of interfacial layer density and the formation of the planar surface structure, thus enhancing the bond strength at the interface. When the content was 13 wt%, it exhibited excellent synergistic effects on adhesive properties, and the adhesive strength reached 1.53 MPa. The possible morphology and composition of the silane primer layer were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). A thermogravimetric infrared spectrometer (TGA-IR) was used to analyze the thermal decomposition of the silane primer layer. The results showed that the alkoxy groups in the silane primer were first hydrolyzed to form Si-OH, and then the dehydration and condensation reactions between Si-OH and the substrate formed a firm network structure.

Study on formation mechanism and corrosion resistance of an environmentally protective insulating coating on non-oriented electrical steel

In the present work, we developed an environmentally protective insulating coating for non-oriented electrical steel, which was composed of phosphate film-forming agent, rare-earth passivating agent, silane coupling agent and polyurethane additive. The morphology, composition, electrochemical properties and corrosion resistance of the coating were characterized by scanning electron microscopy (SEM), confocal Raman microscopy (CRM), scanning vibrating electrode technique (SVET), and electrochemical measurements. The formation mechanism of the coating revealed that the synergistic effect of rare-earth passivating agent and silane coupling agent made the distribution of rare-earth oxides uniform and hindered the agglomeration of phosphate. Further addition of polyurethane formed cross-linked network structures with the original coating to enhance corrosion resistance. The electrochemical results indicated a relatively low corrosion current density (0.12 μA cm−2) and a relatively high polarization resistance (143 kΩ cm2). The SVET results illustrated a good passivation effect of the coating, contributing to a continuous protection to the substrate. In addition, the coating could withstand the annealing test for 2 h and resist the neutral salt spray test for 8 h. Consequently, the comprehensive properties of the coating were found to be higher than industrial standards, satisfying application requirements for non-oriented electrical steel.

Effect of silane coupling agent and concentration on fracture toughness and water sorption behaviour of fibre-reinforced dental composites.

This paper presents the effect of silane treatment of S-2 Glass fibres on the fracture toughness and water sorption/solubility behaviour of fibre-reinforced flowable dental composites. The effect of epoxy- and methacrylate-based silane coupling agents (SCAs) on the mechanical strength and hydrolytic properties were investigated. The concentration of the selected SCAs on the mechanical and physical properties were investigated. The influence of molecular structure and concentration in the interfacial adhesion at the fibre-matrix interfaces was also studied. Short S-2 Glass fibres of 250µm in length and 5µm in diameter were etched with acid to remove any impurities and roughen the surface. The acid-etched fibres were silane treated with 3MPS, 3GPS, and 8MOTS at different concentrations by weight (%). The silane-treated fibres were incorporated at 5 % into the dental resin mixture. Untreated fibres were added at 5 % to the dental resin mixture and served as the control group. The physical properties such as water sorption, solubility, and desorption along with mechanical properties such as fracture toughness and total fracture work of the fibre-reinforced dental composites grafted with the above-mentioned SCAs were evaluated. The surface morphology of the fractured surface was studied and analysed. The fracture toughness tests showed that the dental composites grafted with optimum weight per cent (wt. %) concentration of the SCA had a better stress intensity factor (KIC) when compared to the 2.0wt. % and 3.0wt. % concentration. The KIC value of dental composites grafted with untreated surface etched glass fibres was less than the KIC values of dental composites grafted with optimum concentrations of 3MPS, 3GPS, and 8MOTS by 81.6 %, 38.6 %, and 110.5 %, respectively. A similar trend was found while investigating the total work of fracture of the dental composites, between optimum concentration, 2.0wt. % and 3.0wt. % concentration of respective SCA. The increase in silane concentration also led to an increase in the water sorption/solubility characteristics. The absorption of water was most severe in the fibre-reinforced dental composites without silane treatment (32.9µg/mm3). The ANOVA results showed that the fibre-reinforced dental composites grafted with 8MOTS at optimum concentration showed an increase in fracture toughness when compared to optimum concentrations of 3GPS and 3MPS by 51.9 % and 15.9 %, respectively. The enhanced mechanical and physical characteristics are due to the increased adhesion between the fibre and silane achieved from the optimum wt. % concentration of 8MOTS. Similarly, dental composites grafted with 8MOTS at optimum concentration showed a decrease in water sorption characteristics when compared to optimum concentrations of 3GPS and 3MPS by 18.2 % and 0.6 %, respectively. The decreased water sorption characteristics at the optimum concentration of 8MOTS could be due to the reduced availability of reactive hydroxyl groups and the hydrophobic characteristics of 8MOTS. Silane coupling agents (SCAs) are important components of dental composites. The type and concentration of SCA have a significant effect on material properties. The current study focuses on understanding the effects of different SCAs and wt. % concentrations on the interfacial fracture behaviour and the influence of different SCAs on the water sorption and solubility behaviour of S-2 Glass fibre-reinforced flowable dental composites.

Effect of Different Silane Coupling Agents In-Situ Modified Sepiolite on the Structure and Properties of Natural Rubber Composites Prepared by Latex Compounding Method

With the increasing demand for eco-friendly, non-petroleum-based natural rubber (NR) products, sepiolite, a naturally abundant, one-dimensional clay mineral, has been identified as a suitable material for reinforcing NR through the latex compounding method. To create superior NR/sepiolite composites, three silane coupling agents with different functional groups were used to modify sepiolite in situ via grafting or adsorption during the disaggregation and activation of natural sepiolite, which were subsequently mixed with natural rubber latex (NRL) to prepare the composites. The results showed that the modified sepiolite improved the dispersion and interfacial bonding strength with the rubber matrix. VTES-modified sepiolite containing C=C groups slightly improved the performance but retarded the vulcanization of the NR composites, and MPTES and TESPT-modified sepiolites containing -SH and -S4- groups, respectively, effectively accelerated vulcanization, inducing the composites to form a denser crosslink network structure, and exhibiting excellent dynamic and static properties, such as the modulus at a 300% increase from 8.82 MPa to 16.87 MPa, a tear strength increase from 49.6 N·mm-1 to 60.3 N·mm-1, as well as an improved rolling resistance and abrasive resistance of the composites. These findings demonstrate that modified sepiolite can be used to produce high-quality NR/sepiolite composites with enhanced properties.

Verification of mechanism for effect of silane coupling agent modification of polyethylene (PE) fiber's surface on strain-hardening behavior of high-strength cementitious composites

To fully understand the mechanism for the effect of silane coupling agent (SCA) modified polyethylene (PE) fiber on the strain-hardening behavior of high-strength cementitious composites (HSCC), an experimental research has been conducted, including direct tension and microstructural tests using optical microscope, scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that, compare to the interfacial bonding between original PE fiber and very high strength matrix of cementitious composite at water/binder ratio (W/B) of 0.18, the interfacial bonding was strengthened after the modification of PE fiber's surface by SCA solution of 3% concentration, which subsequently resulted in the improvement of initial-cracking stress, ultimate tensile stress and ultimate tensile strain from 5.20 MPa, 6.34 MPa and 0.68% to 7.26 MPa, 8.01 MPa and 5.06%, respectively. The mechanism for the improvement in strain-hardening behavior of HSCC with SCA-modified PE fiber was that the physicochemical interactions occurred between the SCA-modified PE fiber and the matrix. Among these interactions, amino and hydroxyl groups connected to the PE fiber improved the hydrophilicity of fiber surface, which enhanced the physical bonding between the SCA-modified PE fiber and the matrix. More importantly, two types of chemical interactions have been proved to establish chemical bonding between the PE fiber and matrix, namely, the condensation reaction between hydroxyl groups of the modification layer on the PE fiber and hydroxyl groups of C–S–H gels in the matrix, and the combination of the polymer of SCA's hydrolysates with Ca(OH)2 released by cement hydration.

Effect of coupling agents on properties of vegetable fiber polymeric composites: review

Using natural fibers in composites presents a wide range of applications, from furniture to airplanes. In polymeric composite, the use of fiber is to boost strength and stiffness. However, this material presents low mechanical properties compared to virgin polymers due to hydrophilic nature of the fiber and hydrophobic nature of the polymer. It can result in weak bonding matrix/fiber which may cause incompatibility problem in bonding fibers with most of the polymer matrices. To achieve compatibility between surfaces there is a need to modify them, and one alternative is using coupling agents. Maleated coupling agents stand out as option, but their source is petroleum-derived polyolefin. Researchers have been seeking for more environmentally friendly alternatives to replace these materials. Therefore, this work aims to bring a comprehensive review of the mechanical behavior of maleated and ecological coupling agents. Based on the literature, resistance, flexural, and tensile strength were properties discussed.

Effect of moisture absorption-desorption cycles, UV irradiation and coupling agent on the mechanical performance of pinewood waste/polyethylene composites

&lt;abstract&gt; &lt;p&gt;The effects of UV radiation, a maleic anhydride grafted polyethylene (MAPE) coupling agent and moisture cycling exposure on wood plastic composites (WPC) made from pinewood waste (PW) and high-density polyethylene (HDPE) on their tensile and flex properties, were studied. First, the effect of UV radiation and the presence of anhydride grafted polyethylene on the absorption-desorption behavior of the compounds was evaluated and then its effect on the mechanical properties. Scanning electron microscopy (SEM) was used to analyze the surfaces of the samples subjected to these factors and their subsequent damage in fracture zones of the samples. The moisture absorption-desorption process exhibited a two-stage mechanism: the first is significant increases in the absorption values in the first five cycles, and a second stabilization stage that occurs from the sixth cycle onwards. The first stage includes several steps: initial absorption and delamination; capillary action and polymer-wood interaction; and swelling, fiber-matrix interaction and mechanical damage. The second stage involves the balance and stabilization step. Statistically, it was found that the changes in the humidity values in the absorption and desorption cycles show that UV radiation has a significant contribution with the effect of increasing the absorption and desorption values, while the presence of anhydride grafted polyethylene as a lesser effect with an effect of decreasing those values. The tensile and flexural properties of the compounds were significantly affected by UV radiation and moisture cycling. Taking the sample without anhydride grafted polyethylene and without treatments as a reference, only a slight increase of 5–12% in its tensile and flexural properties was observed, while treatments with UV radiation and absorption-desorption cycles reduced them by up to 45%. The SEM analysis confirmed the deterioration of the composites in the form of microcracks, delamination, interfacial voids and mechanical failures in both the wood filler and the polyethylene matrix, especially in the samples exposed to ultraviolet radiation, where this deterioration was lower in the samples containing anhydride grafted polyethylene.&lt;/p&gt; &lt;/abstract&gt;

A review study on coupling agents used as ceramic fillers modifiers for dental applications

The aim of this study is to provide a review on silanized composite performance when exposed in a complex wet aqueous environment and the role of titanium coupling agent as a more stable and reinforcement material in the construction of dental composites. Silanes are considered as the most dominant materials used for surface modification of the filler added to the polymer material in dental applications. Due to the presence of silica in the silane structure, so, the silane coupling agent were considered to be more effective in modifying materials which are consisting of silica because of the similarity in their ordered structure. Silanes are relatively characterized by dehydration inside the oral aqueous environment. On the other hand, titanate coupling agents are effective in serving at a wet environment, because its ability to react with the positive proton available on the surface of the filler (H+). TCAs are superior in performance in comparison to silane by creating a strong internal bonding between the filler and polymer matrix, and having a significant effect on the dispersion and resolving of particles agglomeration and good hydrolytic stability inside the mouth. This paper presents a comparative study between the effects of silane coupling agents against the TCAs performance in oral environment.

Superparamagnetic wood‐polypropylene nanocomposite made using magnetic wood flour with a nanoparticle‐free surface

AbstractThis study investigates the effect of removing magnetic nanoparticles from the outer surface of magnetic wood flour (MWF) particles as a filler phase on the microstructural, physical, and mechanical properties of the prepared MWF‐polypropylene nanocomposites. For producing MWF with a surface free of magnetic nanoparticles (called LFMWF), in contrast to the commonly produced MWF (called FFMWF), magnetic wood chips were first prepared and then milled. No significant changes were observed in the tensile and flexural strength of the composite specimens prepared with the LFMWF filler instead of the FFMWF. The samples containing the LFMWF filler showed lower water uptake and higher thickness swelling after 400 h of immersion. The coupling agent's effect on improving the mechanical properties of the specimens was more pronounced than its effect on the water uptake and thickness swelling of the specimens. The saturation magnetization of LFMWF was about 4.3 emu/g, while that of FFMWF was 0.94 emu/g. After melt compounding the MWFs with the polymer matrix, the saturation magnetization decreased; this decrease was about 9.9% higher for the FFMWF‐containing magnetic nanocomposites than for the LFMWF‐containing ones.