Effect Of Chemical Surface Treatments Research Articles

Effect of surface treatment on the performance of composite‐composite and composite‐metal adhesive joints

AbstractThe use of Fiber‐Reinforced Polymer Composites (FRPCs) in automotive, aerospace, and naval applications has increased significantly due to the requirement for a high performance‐to‐weight ratio. One the issue in using composite parts is their joining to the metal parts in the global structure. Several joining techniques such as mechanical joining, adhesive, vibration joining, and hybrid joining are used for this purpose. Being lighter in weight and lower in cost in comparison to other techniques, adhesive bonding is mostly used for composite‐composite and composite‐metal joining. To achieve reliable adhesive joining, surface preparation of the joining substrates is of utmost importance. Though the effect of physical surface treatments on the performance of joints has been reported in the literature, however, the effect of chemical surface treatment of composites on the mechanical performance of adhesive joints was rarely studied. In this article, the effect of chemical treatment (alkaline permanganate), of the composite surfaces on the single lap shear strength and Izod impact strength of composite‐composite and composite‐metal adhesive joints is reported. The results showed that the chemically treated joints demonstrate a significant improvement in these properties.

Assessing the effect of chemical surface treatment and joint surface preparations on transverse strength of repaired denture base resin

The present study was conducted to assess the effect of chemical surface treatment and joint surface preparations on transverse strength of repaired denture base resin. The study included 120 specimens divided into 8 groups of 15 samples each based on the combination of chemical surface treatment with either methyl methacrylate, ethyl acetate, or methylene chloride and chemical surface treatment of rounded joint, 45° bevel, and butt joint. Following surface treatment, dentures were repaired with self-cure resin. After treatment, to assess the transverse strength, they were subjected to a 3‑point bending test. Surfaces that were fractured were assessed under the microscope and were analyzed to AutoCAD for assessing cohesive or adhesive failure type and the area was measured. The study results showed that a statistically significant difference was seen in most of the comparisons done. Specimens with rounded joints and methylene chloride used for 60 seconds showed the gain of strength of 60%-70& in the present study. The present study concludes that to attain better bond strength in a specimen repaired, the fractured segments of the specimens should be etched with methylene chloride for 60 s and should be given the rounded joints.

The Effect of Chemical Surface Treatment on Mechanical Performance of Electrically Conductive Adhesives

The Effect of Chemical Surface Treatment on Mechanical Performance of Electrically Conductive Adhesives

Effects of surface treatment on Fermi level pinning at metal/GaN interfaces formed on homoepitaxial GaN layers

The effect of chemical surface treatment on the uncontrolled surface oxide at a GaN surface and on Fermi level pinning at subsequently formed metal/GaN interfaces was investigated for a GaN epitaxial layer grown on a GaN substrate. The impact of several chemical treatments, including photolithography, on the surface oxide and the resultant surface band bending at the GaN surface was examined by X-ray photoelectron spectroscopy. Surface band bending was reduced by the reduction in the amount of uncontrolled surface oxide. The metal/GaN interfaces formed subsequent to these chemical treatments were investigated by electrical measurement for Schottky barrier diodes. We found that the reduction in the amount of uncontrolled surface oxide leads to an increase in the slope factor in the metal-work-function dependence of the Schottky barrier height. The mechanism of Fermi level pinning at the metal/GaN interface is discussed.

Effect of chemical surface treatment of titanium on its bond with dental ceramics

Statement of problemAirborne-particle abrasion of titanium is a clinically accepted method of surface preparation. As a side effect of airborne-particle abrasion, particles of the abrasive material get embedded into the surface. How particle presence or removal from the titanium surface affects the strength of the titanium-ceramic bond is unclear. PurposeThe purpose of this in vitro study was to determine the effect of removing Al2O3 particles embedded into the surface by means of chemical surface treatment on the strength of the titanium-ceramic bond. Material and methodsTitanium (TritanCpTi 1, Dentaurum, 99.5% Ti) disks were airborne-particle abraded with 110 μm Al2O3 at a pressure of 0.4 MPa and an angle of approximately 45 degrees. The surface was etched chemically using 1 of 8 reagents, and the veneering ceramic applied and fired. The strength of the metal-ceramic bond was determined using the shear strength test. Further, the effect of thermal fatigue on the bond strength was evaluated. The results were analyzed with 2-way ANOVA and the Tukey honest significant difference (HSD) test (α=.05). Fractographic investigations and microscopic tests were also performed to determine the quality of the titanium-ceramic bond. ResultsEffective etching of the titanium surface and removal of Al2O3 particles included a 30% water solution of HNO3 + 3% HF, a mixture of HNO3 + HF + glycerin, a 4% solution of HF in H2O2, and a 4% solution of HF in H2O. A statistically significant difference (of about 50%) in bond strength was found between the groups subjected to chemical etching and the control group (P<.05). Additionally, a statistically significant difference (about 25%) was found after thermocycling (P<.05). ConclusionsRemoving the Al2O3 particles embedded into the titanium surface after airborne-particle abrasion lowers the strength of the titanium-ceramic bond (P<.05). Thermocycling also weakens the strength of the titanium-ceramic bond, regardless of the surface preparation (P<.05).

Effect of Chemical Surface Treatment on Flax-Reinforced Epoxy Composite

ABSTRACTThe aim of this study is to examine the impact of surface modification on properties of flax fiber and flax-reinforced composites. For this purpose, acetic anhydride, sodium hydroxide, and silane were used to treat surface of the flax fiber. The effects of treatments on fiber were investigated by using contact angle, attenuated total reflectance-Fourier transform infrared, atomic force microscopy (AFM), and scanning electron microscopy (SEM). Contact angle and AFM results revealed that sodium hydroxide-treated flax fibers have higher adhesion force on the fiber surface. Particularly, NaOH treatment improved the mechanical properties of the epoxy matrix composite.

Chemical surface treatment with toluene to enhance sensitivity of NO 2 gas sensors based on CuPcTs/Alq 3 thin films

Abstract A nitrogen dioxide (NO 2 ) gas sensor based on the blend of copper phthalocyanine-tetrasulfonic acid tetrasodium/tris-(8-hydroxyquinoline)aluminum (CuPcTs/Alq 3 ) thin films was fabricated. The effect of chemical surface treatment with toluene on the structural, surface morphology and device sensitivity has been examined. The X-ray diffraction (XRD) patterns of as-deposited and toluene-treated films exhibit a broad hump peak at 2 θ = 24°. The atomic force microscopy (AFM) measurements show that the average particle diameter decreases with immersing time. The needle like shapes can be seen from scanning electron microscopy (SEM) images for films treated with toluene for an immersing time of 60 min. Gas sensor characterizations demonstrate that all samples have superior NO 2 gas sensitivity at a operating temperature of 373 K. The increase of the sensor sensitivity with increasing chemical treatment time up to 60 min was observed. All films show the stable and repeatable response patterns.

The effect of chemical surface treatment on the fracture toughness of microfibrillated cellulose reinforced epoxy composites

We conducted the surface modification of a microfibrillated cellulose (MFC) as a reinforcing filler of epoxy resin with triethoxy(3-glycidylpropyl)silane (GPS) to increase the mechanical properties of epoxy composite. The chemical modification for the surface of pristine MFCs was confirmed by FT-IR and SEM/EDX. Two different epoxy composite series were prepared using the pristine MFCs and GPS-modified MFCs (GPS-MFCs) to investigate the mechanical properties and fracture toughness of the epoxy composites according to the cellulosic filler contents. The tensile and impact properties of the epoxy composites showed the better performance of GPS-MFC/epoxy composites than of the pristine MFC/epoxy composites. The results of the critical stress intensity factor (KIC) and the critical strain energy release rate (GIC) show the improved interfacial adhesion between epoxy matrix and cellulosic filler in the GPS-MFC/epoxy composites, and their enhanced fracture toughness.

Combined Effect of Chemical Surface Treatment of Kevlar Fabric and PTFE Fillers on the Water-Involved Tribological Performance of Kevlar Fabric/Phenolic Laminate

ABSTRACTThe combined effect of chemical surface treatment of Kevlar fabric and solid lubricant polytetrafluoroethylene (PTFE) fillers on the water-involved tribological performance of Kevlar fabric/phenolic resin laminate was investigated. Results showed that the interfacial adhesion between Kevlar fabric and resin was improved because of chemical surface treatment on the Kevlar fabric, leading to a decreased wear rate but an increased friction coefficient of the laminate. The addition of PTFE fillers not only enhanced the wear resistance of the laminate but reduced its friction coefficient. Furthermore, the combination of surface treatment on Kevlar fabric and the PTFE filling can improve the wear resistance and friction-reducing property of the laminate to the largest extent.

Tensile bond strength between auto-polymerized acrylic resin and acrylic denture teeth treated with MF-MA solution.

PURPOSEThis study evaluated the effect of chemical surface treatment using methyl formate-methyl acetate (MF-MA) solution on the tensile bond strength between acrylic denture teeth and auto-polymerized acrylic resin.MATERIALS AND METHODSSeventy maxillary central incisor acrylic denture teeth for each of three different brands (Yamahachi New Ace; Major Dent; Cosmo HXL) were embedded with incisal edge downwards in auto-polymerized resin in polyethylene pipes and ground with silicone carbide paper on their ridge lap surfaces. The teeth of each brand were divided into seven groups (n=10): no surface treatment (control group), MF-MA solution at a ratio of 25:75 (v/v) for 15 seconds, 30 seconds, 60 seconds, 120 seconds, 180 seconds, and MMA for 180 seconds. Auto-polymerized acrylic resin (Unifast Trad) was applied to the ground surface and polymerized in a pressure cooker. A tensile strength test was performed with a universal testing machine. Statistical analysis of the results was performed using two-way analysis of variance (ANOVA) and post-hoc Dunnett T3 test (α=.05).RESULTSThe surface treatment groups had significantly higher mean tensile bond strengths compared with the control group (P<.05) when compared within the same brand. Among the surface treatment groups of each brand, there were no significantly different tensile bond strengths between the MF-MA groups and the MMA 180 second group (P>.05), except for the Yamahachi New Ace MF-MA 180-second group (P<.05).CONCLUSION15-second MF-MA solution can be an alternative chemical surface treatment for repairing a denture base and rebonding acrylic denture teeth with auto-polymerized acrylic resin, for both conventional and cross-linked teeth.

화학적 표면처리가 열중합형 의치상 레진과 이장재간의 굴곡결합강도에 미치는 영향

화학적 표면처리가 열중합형 의치상 레진과 이장재간의 굴곡결합강도에 미치는 영향

Mechanical Properties and Chemical Resistance of Short Tamarind Fiber/Unsaturated Polyester Composites: Influence of Fiber Modification and Fiber Content

In the present work, tamarind fibers were extracted from ripened fruits by the water retting process. Using these fibers as reinforcement and unsaturated polyester as matrix, composite samples were prepared by the hand lay-up technique. The effect of chemical surface treatments (alkali and silane) of tamarind fibers on the mechanical properties, chemical resistance, and interfacial bonding was studied. The mechanical properties of the composites with surface modified fibers were found to be higher than those with unmodified fibers. Morphological studies indicated improvement of interfacial bonding by alkali and silane coupling agent treatments of the fibers. The composites were found to be resistant to many chemicals.

Effect of chemical surface treatment on the push out bond strength of quartz fiber posts

Effect of chemical surface treatment on the push out bond strength of quartz fiber posts

Effect of chemical surface treatment on the mechanical properties of reinforced plasticized poly(lactic acid) biodegradable composites

Biodegradable composites were prepared by melt-blending technique using 30 wt% kenaf bast fiber (KBF) to reinforce 70 wt% plasticized poly(lactic acid) (PLA). The KBF was treated with various percentages of sodium hydroxide (NaOH), whereas 5% triacetin was used as plasticizer. The effects of the KBF surface treatments on the tensile, flexural, impact strength, and DMA of the biocomposites were investigated. Tensile, flexural, and impact testing results reveal that 4% of NaOH-treated KBF produced composites with optimum tensile strength (62 MPa), flexural strength (67 MPa), and the impact strength (42 kJ/m2). The removal of the lignin from the fiber during the surface treatment caused the increment in the modulus result. This finding is also supported by the dynamic mechanical analysis. The storage modulus of plasticized PLA/treated KBF is higher than the storage modulus of plasticized PLA/untreated KBF which is attributed to the enhancement of the fiber—matrix adhesion. The loss modulus results showed that the Tg of the plasticized composites was shifting to higher temperature, from 55°C for plasticized PLA/untreated KBF to 65°C for plasticized PLA/treated KBF. The increase in Tg shows that the plasticized PLA has low chain mobility when reinforced with treated KBF, indicating better interaction.

The Effect of Chemical Surface Treatments on the Flexural Strength of Repaired Acrylic Denture Base Resin

To investigate the effect of the selected chemical surface treatment agents on the flexural strength of heat-polymerized acrylic resin repaired with autopolymerized acrylic resin. Ninety heat-polymerized acrylic resin specimens (Meliodent) were prepared according to ISO1567 and randomly divided into nine groups: positive and negative control groups (groups I and II), and seven experimental groups (groups III to IX). Specimens in groups II to IX were cut in the middle and beveled 45°. Group III was then treated with methyl methacrylate (the liquid part of Unifast TRAD) for 180 seconds. Group IV was treated with Rebase II adhesive according to the manufacturer's instructions. Groups V to IX were treated with methyl formate, methyl acetate, and a mixture of methyl formate-methyl acetate at various concentrations (75:25, 50:50, 25:75% v/v, respectively) for 15 seconds. They were then repaired with autopolymerized acrylic resin (Unifast TRAD). A three-point loading test was performed using a universal testing machine. One-way ANOVA and post hoc Tukey's analysis at p < 0.05 were used for statistical comparison. Failure analysis was then recorded for each specimen. The morphological changes in untreated and treated specimens were observed by scanning electron microscopy. The flexural strengths of groups III to IX were significantly higher than that of group II (p < 0.05). The flexural strengths of groups IV to IX showed no significant difference among them (p > 0.05). All specimens in groups V to IX showed 100% cohesive failure, while groups II, III, and IV showed cohesive failure of 10%, 60%, and 60%, respectively. From scanning electron micrographs, the application of methyl formate, methyl acetate, and a mixture of methyl formate-methyl acetate solutions on heat-polymerized acrylic resin resulted in a 3D honeycomb appearance, while specimens treated with methyl methacrylate and Rebase II adhesive developed shallow pits and small crest patterns, respectively. Treating surfaces with methyl formate, methyl acetate, and a mixture of methyl formate-methyl acetate solutions significantly enhanced the flexural strength of heat-polymerized acrylic denture base resin that had been repaired with autopolymerized acrylic resin.

Effect of chemical surface treatments on interfacial and electrical characteristics of atomic-layer-deposited Al2O3 films on Ge substrates

The Ge surfaces were cleaned and passivated by two kinds of chemical pretreatments: conventional combination of HF+(NH4)2S, and new one of HBr+(NH4)2S. The chemical states and stability at passivated Ge surfaces were carefully characterized. The influence of chemical surface treatments on the interface and electrical properties of Al2O3 gate dielectric films on Ge grown by atomic layer deposition (ALD) has been investigated deeply. It is found that the combination of HBr and (NH4)2S can remove more Ge–O bonds on the Ge surface compared to that of conventional HF and (NH4)2S with excellent stability. X-ray photoelectron spectroscopy (XPS) reveals that HBr and (NH4)2S treated Ge surface has a mixture states of GeOx (9.25%) and GeS (7.40%) while HF and (NH4)2S treated Ge surface has a mixture states of GeOx (16.45%) and GeS (3.37%). And the Ge–S peak from the surface of Ge substrates decreases a little after the HBr and (NH4)2S treated Ge surface was exposed in the ambient for 300min, which suggests the Ge surface is stable to oxidants. The Al2O3 films on HBr and (NH4)2S treated Ge substrates exhibits better electrical properties such as large capacitance, decreased leakage current density by ∼two orders of magnitude, and less C–V hysteresis. This indicates that a reduction in charge traps possibly at the interface and more interface traps are terminated by sulfur. The surface treatment of HBr and (NH4)2S seems to be very promising in improving the quality of high-k gate stack on Ge substrates.

The effect of chemical surface treatments on the flexural strength of repaired acrylic denture base resin material

The effect of chemical surface treatments on the flexural strength of repaired acrylic denture base resin material

Effect of surface treatment on the mechanical properties of rice straw fibre

The quality of the fibre-matrix interface is significant for the application of natural fibre as reinforcement fibre for plastics. Chemical treatments can be used to optimise this interface. The modification methods are of different efficiency for the adhesion between matrix and fibre. In the present study, the effect of chemical surface treatment on mechanical properties of natural fibre was discussed. The effects of surface treatment and concentration on natural fibre were evaluated by means of strength distribution, elastic modulus and scanning electron microscopy.

Effects of chemical surface treatments of quartz and glass fiber posts on the retention of a composite resin

Failure of a fiber post and composite resin core often occurs at the junction between the 2 materials. This failure process requires better characterization. The purpose of this study was to evaluate the effect of 2 chemical solvents, hydrogen peroxide and methylene chloride, on the shear bond strength of quartz and glass fiber posts to a composite resin. Twenty-four posts (3 +/-0.1 mm in length) were prepared for each quartz (LIGHT-POST (LP)) and glass fiber (Cytec blanco (CB)) post. Posts were horizontally embedded in acrylic resin with half of the post diameter exposed. The exposed surfaces were successively ground with 400-, 800-, and 1200-grit silicon carbide papers, to ensure uniform smoothness. The specimens were divided into 3 subgroups (n=8) representing different surface treatment techniques, including application of silane for 60 seconds (S), etching with hydrogen peroxide for 20 minutes (H), and etching with methylene chloride for 5 seconds (M). Silane-treated specimens served as controls. A dual-polymerized composite resin (Tetric EvoCeram) was placed in a polytetrafluoroethylene mold (30 x 2 mm) positioned upon the post specimens and polymerized for 20 seconds with a light-emitting diode (LED) polymerization unit. The specimens were stored in water at 37 degrees C for 24 hours. Shear bond strength values (MPa) of posts and composite resin cores were measured using a universal testing machine with a crosshead speed of 0.5 mm/min. Data were analyzed by 2-way analysis of variance (ANOVA). Post hoc Tukey intervals for comparison among the 2 post materials and 3 surface treatment techniques were calculated (alpha =.05). The effect of the chemical surface treatments on glass and quartz fiber post surfaces were examined with a scanning electron microscope (SEM). There were significant differences between the shear bond strength for LP and CB (P<.001). For all groups, the application of H showed the highest bond strength values. There was no significant difference between the S and M groups (P>.05). The SEM observations demonstrated that the fiber post surfaces were modified after chemical surface treatment techniques. The surface treatment of quartz and glass fiber posts with hydrogen peroxide significantly enhanced the shear bond strength of the composite resin tested due to its ability to dissolve the epoxy resin matrix used in each post. The lowest bond strength was obtained with M and S groups. Application of methylene chloride to the fiber post surfaces for 5 seconds was not effective in increasing the shear bond strength of the fiber post to composite resin.

Effect of Surface Treatments on Viscoelastic Measurements of Thread-like Micellar Solutions

Thread-like micelles are formed in aqueous solutions of cationic surfactants and a certain type of salts, and for some of these solutions, the strain hardening behavior is observed after inception of shear flow at high shear rates. In the present study, we examined the effect of chemical surface treatments of the cone-and-plate fixture made of glass on measurements of strain hardening behavior of the thread-like micellar solutions. The untreated glass fixture gave significantly weak strain hardening behavior, when compared with the ordinary stainless steel fixture. This could be attributed to the slippage of the solution on the surface of fixture. When the surface of glass fixture was modified with trimethychlorosilane to increase the dispersion component of surface free energy, the pronounced strain hardening was observed. Thus, the surface treatment of rheometer fixtures is very important to examine the nonlinear rheology of thread-like micellar solutions.