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Additive manufacturing (AM) typically is more costly than traditional manufacturing processes, but it opens new opportunities for design that are often not fully utilized because of its price. Bonding complex additively manufactured structures to conventional parts is a way of reducing cost, while maintaining design freedom. However, not all polymers used in AM are easily bondable. These materials are typically pre-treated with plasma in order to increase adhesion at the interface. By utilizing the design freedom of AM, it becomes possible to omit this pre-treatment step by producing undercut areas that can be filled by the adhesive during bonding. Instead of adhesive bonding, forces are transmitted by positive fit of the adhesive and the AM part. By producing complex lattice structures with AM that are surrounded completely by adhesive, the strength of these bonds can further be increased. The design of such structures is highly complex, however. This publication shows that AM lattice structures can greatly improve bonding strength of low adhesive polymers and suggest a way of characterizing such structures in lap shear tests in order to separate design influence on such bonds. It could be shown that resulting shear strength is comparable to bonding after plasma pre-treatment. [ABSTRACT FROM AUTHOR]

The surface microstructure is one of the most important factors affecting the mechanical performance of adhesive bonding joint of CFRP materials. The aim of this paper mainly focused on the influence of laser generated microgrooves geometric parameters (groove depth, distances, and patterns) on the shearing strength of CFRP/aluminium alloy adhesive joints. An IR laser with a wavelength of 1064 nm was applied to pretreat the CFRP surface. Scanning electron microscopy (SEM) and confocal laser scanning microscope (CLSM) were used to observe and measure the surface morphology, cross-sectional shape, groove parameters (depth, width) and surface roughness. The single-lap shear experiments were also conducted to exam the quality of the adhesive joint. Meanwhile, failure modes under different groove parameters were examined using a digital camera. The main parameters of the grooves and their interaction effects on the final joint strength were quantitatively analyzed by an interactive orthogonal experimental design. It was concluded that the interaction of groove pattern and groove distance was the most significant factor affecting shear strength, followed by groove pattern and groove distance. [ABSTRACT FROM AUTHOR]

Laser surface pretreatment is an effective approach for improving the mechanical properties of adhesive joints. In the case of laser surface treatment of carbon fibre reinforced polymer (CFRP), ultraviolet (UV) lasers and lower pulse fluence infrared (IR) lasers are usually used to ensure the surface pretreatment quality. With respect to improving the surface treatment efficiency as much as possible, the influence of higher pulse fluence (12.7 J/cm2) IR laser pretreatment parameters on the mechanical properties of CFRP/aluminium alloy hybrid joints were investigated in this study. Scanning electron microscopy (SEM), contact angle measurements, confocal laser scanning microscope (CLSM), and X-ray photoelectron spectroscopy (XPS) were used to analyse the surface modification and failure modes of the adhesive surface. Additionally, the influence of the IR laser pretreatment parameters on the failure mode of CFRP/aluminium alloy adhesive joints under tension loading was discussed. The results showed that in addition to surface free energy, subsurface damage and mechanical interlocking were important factors affecting the shear strength of CFRP/aluminium alloy adhesive joints when a higher pulse fluence IR laser was applied for surface pretreatment. Finally, the optimized laser surface pretreatment parameters considering both the treatment efficiency and quality were obtained for the CFRP/aluminium alloy adhesive joint. [ABSTRACT FROM AUTHOR]

An efficient manufacturing technique and high-strength composite structures are essential in weight-sensitive applications. The current study examines the combined effect of manufacturing techniques and GFRP pin insertion on shear and dynamic behaviour of composite joints. Shear analysis revealed that shear strength of the composite joint is intensely reliant on their manufacturing technique and improved in order: secondary bonding (least effective), co-bonding method, and co-cure joining (highly effective). The fracture mode and joint strength are also reliant on the volume fraction of fibreglass pins. The free vibrational analysis asserted that co-cure joining with a 2% volume fraction of fibreglass pins increased the fundamental natural frequency of composite joints due to the formation of an extrinsic crack bridging zone in the adhesive layer developed a stronger interface between adherent and adhesive. The present study exposes that enhancement in shear properties and free vibrational behaviour can be achieved by selecting the proper manufacturing technique and appropriate volume of fibreglass pins. The co-cure joining with 2% volume fractions of fibreglass pins provided the greatest enhancement in shear properties and natural frequencies of composite joints. [ABSTRACT FROM AUTHOR]

The aim of this study was to review and analyze the evidence on the enamel acid etching time when bonding to primary teeth. The research question was: Does the acid-etching time affect the bond strength to primary enamel? A systematic search across PubMed, Web of Science, Scopus and Google Scholar databases was conducted up to April 2024 to select studies that compared acid etching times on the bond strength values of adhesive systems to the primary tooth enamel. Studies evaluating other materials than adhesive systems, absence of bond strength values as mean and standard deviation, or ineligible comparison between intervention and control were excluded. Two reviewers screened studies for eligibility and assessed risk of bias. Bond strength data was the primary outcome. From 411 screened studies, 7 reports were assessed for eligibility, and 5 studies were included in the systematic review. Four studies had a high risk of bias and one study had a moderate risk of bias. Acid etching times range from 5 to 60 s. Three studies considered 15 s as a shorter acid etching time and the time of 30 or 60 s as a control. Two studies evaluated the effect of acid etching times on bond strength by comparing the 5, 20, 30, and 60 s groups. Only one study found statistically significant differences between the acid etching times. The main limitation of the study was the inclusion of only 5 studies with a high or moderate risk of bias. Longer acid etching times do not appear to improve the enamel bond strength in primary teeth. This is the first comprehensive review of enamel acid etching time on bonding to primary teeth. It may support the similar acid etching time for primary and permanent tooth enamel. [ABSTRACT FROM AUTHOR]

Surface roughness of the adherends represents an important factor for manufacturing a reliable bonded joint in structural applications. In case of bonding of parts in carbon fibre reinforced polymer (CFRP), an increase of roughness parameters can be obtained with various techniques. In this paper, the morphology obtained from a CO2 laser texturing on CFRP laminates were investigated. CFRP laminates were manufactured and subjected to laser texturing with various densities. In particular, the densities of treatment have been defined as a function of the grid dimensions of the texture. Subsequently, non-contact measurements were carried out to evaluate the evolution of the surface roughness parameters as a function of the density of the laser treatment. Results showed a strong correlation between surface roughness and density of treatment. In conclusion, these results were compared with experimental tests, which showed that the mechanical performance for ENF bonded joints was limited only by the flexural mechanical resistance of the CFRP adherends. As a result of this work, the developed laser texturing approach is potentially able to increase the mechanical resistance in the function of the real local load acting on the complex bonded joint, optimizing time and cost process. [ABSTRACT FROM AUTHOR]

The aim of this investigation is to generate a basic understanding of the formation of the joining zone of fusion bonded hybrid joints made of press hardened steel (22MnB5) and polyamide 6 (PA6) glass mat reinforced thermoplastic (GMT). To this end, lap-shear samples are produced by varying the steel surface and the fusion bonding temperature. In order to evaluate the resulting joint properties, micrographs of the joining zone are analyzed. Moreover, roughness measurements, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) investigations are used to characterize the steel surface and undercut geometries before joining. By correlating the results of the interface characterization with the mechanical joint strength, optimized fusion bonding parameters can be defined. The results outline the necessity of heating the metal above the melting temperature of the GMT material in order to prevent a solidification in the joining zone. Additionally, the GMT material has to be melted completely to allow the GMT to flow into the geometry undercuts of the AlSi surface. The maximum lap-shear strength is 22.9 ± 2.1 MPa. It was achieved with the samples showing to a metal temperature of 280°C and a GMT temperature of 260°C. [ABSTRACT FROM AUTHOR]

To investigate how plasma treatment affected the surface structure and adhesion to polypropylene matrix and unsaturated polyester matrix, green abaca fibers were treated by low temperature plasma under different plasma processing parameters including treatment time, output power, and working gas. Abaca fibers were characterized by atomic force microscope, X-ray photoelectron spectroscopy, contact angle and interfacial shear strength. The results of contact angle and interfacial shear strength were consistent with the changes in surface roughness and the atomic ratio of the plasma treated abaca fibers with treatment time, output power, and working gas. It was concluded that the surface roughness and atomic ratio played a major role in the adhesion improvement of the plasma treated abaca fibers to polypropylene matrix and unsaturated polyester matrix due to the mechanical interlocking and chemical bonding, respectively. The geometrical potential theory was adopted to elucidate the mechanism of the adhesion property. [ABSTRACT FROM AUTHOR]

Conventional treatment of complex fractures includes the use of plates and nails, which may compromise the affected limb's functionality. Previous studies have demonstrated promising results through chemical, mechanical, and cytotoxicity tests of a chitosan-based adhesive—proposed as a new method to bond high energy fractures—in dry environments with adequate adhesion, malleability, and biocompatibility. In this study, we focused on performing an evaluation of bio-adhesives' mechanical properties and bone-adhesive joint using two chitosan-based formulations (with and without a cross-linking agent). The texture profile analysis determined adhesive properties, such as cohesiveness, adhesiveness, hardness, and resilience at different cure times. Bone-adhesive joint was evaluated according to the tensile bond strength test and shear bond strength test. Fracture toughness and cohesive strength were calculated through a rigid double cantilever beam test at mode I failure. Bone-adhesive joints were tested in two environments: dry and submersed in water at 37 °C for 1, 6, and 24 h (curing time), an approximation of surgery conditions. The experimental results showed an incremental of adhesiveness and hardness of the cross-linked adhesive during the first 15 min, which was determined as the usage time to spread on the bone fracture. The joint interaction between the adhesive and bone surfaces was studied; chitosan-based formulations showed an adhesive joint failure under dry conditions in most of the cases. However, this behavior changed under aqueous conditions, presenting cohesive failures. Under aqueous conditions, cross-linked bone-adhesive presented an augmented tensile bond strength up to 0.024 ± 0.0036 MPa, a shear bond strength up to 0.031 ± 0.0069 MPa, and fracture toughness of 2.38 ± 0.54 J/m2 was observed with a cure time of 24 h. Finally, the presence of the cross-linking agent in the cross-linked bio-adhesive reduced the sensitivity of the adhesive to water; a promising finding that should be explored in future studies. [ABSTRACT FROM AUTHOR]

Abstract In this study, the micro-arc oxidation (MAO) processes in different electrolyte composition ratio were carried out on magnesium alloy sheets and then the carbon fiber reinforced polymer (CFRP)/magnesium alloys laminates were manufactured by using a cure process. The Mode I (peel) interlaminar strength was measured to systematically investigate the effects of the electrolyte concentration on interfacial bonding strength and failure mode of CFRP/Mg laminates in consideration of surface microstructures and roughness. The results show that with the increase of KOH in electrolytes solutions, the Mode I (peel) strength of FMLs performs sharply decreasing due to the decrease of roughness in local regions and the emergence of interspace between magnesium and epoxy. In addition, with the rise of KF in electrolytes solutions, the Mode I (peel) strength of FMLs declines rapidly on account of the sharply weakening of electro-chemical reactions, which causes the decrease of surface roughness. The specimen exhibits the optimal Mode I interlaminar strength of 2.04 N/mm when the KOH and KF concentration is 7.28 g/L and 2.9 g/L, respectively. [ABSTRACT FROM AUTHOR]

A simple method of applying and distributing multi-walled carbon nanotubes (MWCNTs) onto grit-blasted steel substrates has been investigated in this study to overcome the difficulty of mixing MWCNTs in epoxy adhesives forming the MWCNT-reinforced adhesive joints. MWCNTs were dispersed in an acetone and resin (no hardener) solution with the weight ratio of 1:3:100 for MWCNT/resin/acetone, which was then applied onto the grit-blasted steel substrates. After evaporation of acetone, an ultra-thin layer of resin pre-coating kept well-distributed MWCNTs within the micro-cavities created by grit blasting. Epoxy adhesives (with hardener) were then applied to bond the steel substrates to create MWCNTs-reinforced adhesive joints. The results show that the MWCNT pre-coating (PC) method is beneficial to strong adhesive bonding. Most importantly, the MWCNT-PC method can be easily applied for structural applications on site. In the current study, MWCNTs were simply dispersed in the acetone and resin (no hardener) solution by simple rod stirring for around 1 minute, which can be adopted for large-scale applications. Scanning electron microscopy (SEM) observations on fracture surfaces and cross sections of the MWCNT-reinforced adhesive joints showed MWCNT micro-bundles were well dispersed within the epoxy adhesive joints taking the contour of microscopically uneven substrate surfaces. [ABSTRACT FROM AUTHOR]

This article aims to explain the wide range of joint strengths observed depending on the nature of substrate surface geometry by linking the stress distributions in the adhesive layer to the overall strength of the adhesively bonded single lap joints (SLJs). The key factors to which the adhesion strength of non-flat interfaces is attributed are investigated numerically and experimentally. In an attempt to clarify the effect of mechanical interlock on overall adhesion strength of the adhesive joint, zigzag patterns were fabricated on the bonding surfaces of aluminum substrates. It was found that the local compressive and tensile stresses in the vicinity of the interface are the major cause of the practical enhancement or reduction of the joint strength. A comparison between the experimental results of optimum non-flat and standard SLJs showed a strength improvement of up to 40% compared to the conventional SLJ. According to the results of parametric studies, higher wave heights, lower wavelengths, and thinner bond lines improved the efficiency of the method. [ABSTRACT FROM AUTHOR]

A novel concept for joining materials is presented which employs adhesive joints with interlocking bond-surface morphology formed on the surfaces of male and female adherends that mechanically interlock in shear when brought together. In the present work, miniature, single-lap joint specimens with a single truncated square pyramid interlocking profile, centred in the bond area, are investigated. The performance of the concept is assessed through finite element analysis (FEA) by incorporating yield criteria representing plasticity in the adherends and a cohesive zone model to represent damage in the adhesive layer. This allows for effective simulation of the joint response until ultimate failure and thus, full assessment of the concept's performance. Various interlocking geometries are explored and refined through an adaptive surrogate modelling design optimisation procedure coupled with FEA. The results indicated that significant improvements in work to failure, of up to 86.5%, can be achieved through the more progressive failure behaviour observed compared to that of a traditional adhesively bonded joint. Improvements in the joint's ultimate failure load can also be achieved with a relatively ductile adhesive system. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS) films were treated with either oxygen (O 2 ), nitrogen (N 2 ) or argon (Ar) plasma between 40 W and 120 W for 5–15 min and their surface properties studied by contact angle measurements, infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Lower contact angles and increases in surface roughness, assessed by SEM and AFM, were observed for all used gases when plasma power and time increased, with argon treatment being the one that showed the most significant change in roughness. PDMS/collagen type I composites obtained after treating PDMS with oxygen at 80 W for 13 min or nitrogen and argon at 80 W for 14 min showed a peel strength of 0.1N/mm (oxygen plasma), 0.08 N/mm (nitrogen plasma) and 0.09 N/mm (argon plasma). In all cases, peel strength was higher than that measured for the untreated bilayer composite. An increase in adhesion strength, after oxygen and nitrogen plasma, was mostly attributed to chemical interaction between functional groups introduced on the PDMS surface and the functional groups on collagen as detected by FTIR. In contrast, the high peel strength observed on PDMS treated with argon plasma was attributed to its increased roughness which in turn increased mechanical interlocking. The properties of these composites render them suitable for adhesive free skin substitutes. [ABSTRACT FROM AUTHOR]

Indented patterns, about 40 μm wide and 30 μm deep, were created by pressing down a hardened steel file onto the surface of steel substrates using Instron test machine. We examined the penetration of epoxy into those micro-indented patterns and their interactions with Kevlar fibres (diameter of around 12 μm), and their influences on the shear strength of epoxy adhesive joints. To ensure complete wetting of the patterned substrate surface, resin pre-coating was applied first. Three different acetone/resin (without hardener) solutions were prepared for this purpose: they contained 1 wt%, 3 wt% and 5 wt% of resin in acetone, respectively. For the purpose of comparison, plain steel substrates polished by #120 sandpaper were also prepared. It had been found that the patterned substrate coated by the 3 wt% resin/acetone solution yielded the highest shear strength, showing about 20% improvement in comparison with that of polished steel substrates. Only limited Kevlar fibres were found within the indented patterns due to their relatively large spacing and shallowness, and, furthermore, due to the random fibre distribution of Kevlar fibres of around 14 mm in length. The limited Kevlar fibre bridging activities were reflected by only around 4% improvement in the shear strength. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the immediate and the long-term push-out bond strength of glass fiber posts (GFP) cemented with conventional or self-adhesive dual-curing resin cements, at different root depths. Prior to cementation, the GFP (Reforpost #3, Angelus) were etched with 37% phosphoric acid for 30 s followed by silane for 1 min. Thirty canine roots were divided into two groups (n = 15) according to resin cement type: ARC – dual resin cement (RelyX ARC/3M ESPE) combined with an three-step etch-and-rinse adhesive (Adper Scotch Bond Multi-Purpose Plus 3M/ESPE) or U200 – self-adhesive resin cement (RelyX U200/3M ESPE). The manufacturer’s instructions were followed. After 48 h, the roots were cross-sectioned at three different depths, resulting in serial slices corresponding to the cervical, middle, and apical root thirds. Slices were randomly divided into two groups, according to the period of water storage prior to push-out bond strength analysis: 48 h or 180 days. The data (MPa) were analyzed using three-way ANOVA for randomized blocks (p < 0.05), which showed no significant interaction between the three factors (p = 0.716). The main study factors were also proven not significant (cement:p = 0.711; time: 0.288; root third:p = 0.646). In conclusion, root depth, cement type (self-adhesive or conventional), and storage in water for 180 days did not influence the bond strength of GFP to intracanal dentin. [ABSTRACT FROM AUTHOR]

Bond shear strength is one of the governing characteristics that determines the failure in FRP composite structures and needs investigation. Multi-walled carbon nanotubes (CNTs) have recently gained popularity in various structural applications to enhance mechanical properties. The improvement in the bond shear strength of glass fibre-reinforced plastic (GFRP) splices by incorporating different percentages of MWCNTs in the adhesive is experimentally investigated in this study. Experimental results reveal that the optimum amount of MWCNTs results in approximately a 30% increase in bond shear strength. The bond shear strength may vary because of differential splice geometry, material properties, etc., even though the splices are prepared using the same materials and procedures. The current research further investigates the variability in the bond shear strength of lap splices statistically using Goodness-of-fit tests, namely Kolmogorov-Smirnov (K–S), Anderson-Darling (A-D), and Chi-Square (C–S). Appropriate statistical distributions for modelling the variability in the bond shear strength are obtained. The Gumbel Max and Gumbel Min distributions are recommended to model the variability in the bond shear strength of single-lap GFRP splices without MWCNTs and with 0.1% MWCNTs. Knowledge of the variability of the bond shear strength property will help the reliability-based structural analysis of FRP composite structures. [Display omitted] • Bond shear strength governs the behaviour of GFRP lap splices. • MWCNTs in the lap splice adhesive for performance enhancement. • Significant variability in the performance of GFRP lap splices can be observed. • Goodness-of-Fit tests for modelling variability of bond shear strength. • Appropriate statistical distributions that describe experimental data. [ABSTRACT FROM AUTHOR]

To improve adhesive strength, this study investigated a surface modification technique that is inexpensive, semi-permanently effective, and applicable to large areas and inflexible thermoplastics, such as polypropylene (PP). In order to achieve this objective, undercut micropatterns were created on PP plates by a roll-imprinting process to introduce mechanical interlocking. The roll-imprinting molds with various undercut micropatterns were first fabricated using a wire-cut electrical discharge machine. Then, the imprinting process was carried out by controlling the temperature of the PP plate so that it was heated to its crystalline melting temperature just before imprinting and cooled to around the Vicat softening temperature during demolding. The improvement of the adhesive joint strength was then evaluated by performing butt-joint tensile tests on specimens with various undercut angles. The tensile adhesive strength was found to increase with the undercut angle, and the adhesive strength of the 25° undercut angle specimen with the general-purpose epoxy adhesive was 1.7 times higher than that of the specimen without surface modification and with the expensive commercially available cyanoacrylate adhesive specially developed for PP. This result clarified that the mechanical interlocking due to the undercut micropattern could improve the adhesive strength of PP at low material cost. [ABSTRACT FROM AUTHOR]

The adhesion of silver colloids to a polyimide (PI) substrate was investigated in this study. This issue would be of concern when one tried to print electronic circuits on a flexible PI substrate. To enhance the adhesion between them, the PI surface was first roughened by using the sandblasting technique, and varying degrees of roughness were achieved using various sizes of alumina particles and various air pressures for sandblasting. The adhesion strength of silver colloids to the PI substrate after sintering was then measured according to both ASTM D4541 and ASTM 3359 standards. The results indicated that adhesion strength increased proportionally with surface roughness; however, this enhancement effect was lessened when the roughness was above 880 nm. Sintering temperature was also beneficial in increasing adhesion to the substrate; however, the electrical resistance of the silver colloids after sintering also increased with the degree of roughness. This implied that the packing of silver colloids was also affected by surface roughness. Consequently, values of surface roughness were optimal when adhesion strength and electrical resistivity were balanced. [ABSTRACT FROM PUBLISHER]

This work reports on an improved ultrasonic welding process for the direct joining of thermoplastic and metal. A metal thin plate was structured with grid arrays on a micro-scale level by laser irradiation. A thermoplastic part was placed on the structured region, and ultrasonic welding or ultrasonic hot welding was applied. The thermoplastic was locally melted and re-solidified in the structured grooves with very low energy input due to the tiny initial contact area of the grid tips. Single lap shear specimens and boss specimens were used to study the feasibility and performance of hybrids made by this joining method. Both shear strength and normal tensile strength were affected by changes in the grid structures and welding parameters, and the experimental results show that the micro-structure geometry of the metal plate is a major factor in the joining strength. Successful welds required that process cycle times be less than 1 s. Furthermore, the mold holding the metal sheet was heated in the ultrasonic hot welding experiments, and the heated mold significantly enhanced the joint quality. Ultrasonic hot welding appears to be a fast, low cost, and reliable method to produce plastic/metal hybrid products for electronics and other industrial applications. [ABSTRACT FROM AUTHOR]

The present study aims to validate bond strength of SLJs with dissimilar adherends such as CFRP and Aluminum. Aluminum adherend was considered for surface treatment using Resin pre-coating (RPC) and NaOH for SLJs, as well as mixing structural elements (ZnO tetrapods) within the adhesive. Young-Laplace measurement technique was used to determine the contact angle for specimens with different surface treatments. Nondestructive testing (NDT) methods like ultrasonic testing(UT) and X-ray radiography were used to determine the defects of the SLJs. The strength of the bond was assessed using flexural and tensile test equipment in UTM. Improved bonding performance was observed in terms of maximum load and shear strength of RPC surface treated specimens when compared to surface specimens without treatment. The structural elements mixed into adhesive showed improved bonding performance in terms of flexural strength. A numerical simulation model was developed for validating the results. The morphological studies of de-bonded joints to analyze the bonding mechanism in each group of specimens with maximum load bearing were done. • NDE ensures the quality of single lap bonded joints. • Zno tetrapod structural elements doped with adhesive. • Experimental results validated with Simulated models. [ABSTRACT FROM AUTHOR]

Recently, self-adhesive flowable composite resins (SAFC) have been introduced to dental practice to simplify the clinical procedure and to reduce the treatment time but with limited data regarding their bonding performance to dentin. The aim of this in vitro study was to evaluate the micro-shear bond strength (μ-SBS) of a giomer SAFC (FIT SA F03 – FSA) bonded with different modes to dentin after artificial aging. Additionally, a qualitative evaluation of the hybrid layer formation after different adhesive modes was performed using scanning electron microscopy (SEM). A flowable giomer composite resin (Beautifil Flow Plus F03 – BFP) was used as control. Fifty sound human molars were used for providing the dentinal substrates. The experimental groups of the study were five; two for BFP, where the specimens bonded to dentin using etch-and-rinse (Optibond FL) and self-etch (Clearfil SE Bond 2) strategy, and three for FSA, where self-adhesive mode was also applied. The μ-SBS test was applied after 24 h and after thermocycling. Etch-and-rinse and self-etch modes exhibited significant higher μ-SBS compared to self-adhesive mode for FSA (p < 0.05). Adhesive failures were predominant for both materials regardless of the adhesive mode and there was an increase in adhesive failures after thermocycling. Uniform hybrid layer was observed for the dental adhesives used, whereas visible gaps appeared when the self-adhesive mode was applied. FSA presented inferior behavior when bonded to dentin following the self-adhesive mode, while the best approach for BFP seemed to be the two step self-etch adhesive mode. [ABSTRACT FROM AUTHOR]

An experimental study was done to measure the force of adhesion of molten wax droplets, 3.1 mm in diameter, dropped from heights ranging from 20 to 50 mm onto porous polyethylene and Teflon surfaces. The Teflon surface had 0.25-mm holes drilled in it and the three polyethylene surfaces had random pores with mean diameters of 35, 70, and 125 μm, respectively. The force required to remove the solidified ink from the surface was measured using a pull test. Wax splats were attached to the substrate by both adhesive and cohesive forces. The cohesive force was calculated by multiplying the ultimate tensile strength of the wax (2.2 MPa) by the cross-sectional area of the wax penetrating into surface pores. The adhesive force was obtained by multiplying the contact area between the wax and substrate by the adhesion strength per unit area, estimated to be 0.2 MPa for polyethylene and 0.1 MPa for Teflon surfaces. The contact area between splats and the substrate was typically about 60–70% of the splat area. The edges of splats lifted up, preventing complete contact. [ABSTRACT FROM PUBLISHER]

The aim of the presentin vitrostudy was to evaluate the effect of chlorhexidine, applied before a self-etching adhesive system (Clearfil SE Bond) on microtensile bond strength to superficial and deep dentin (DD), immediately and after six months of water storage (WS). Forty dentin specimens were divided into two groups according to dentin depth: superficial and deep. The specimens were then divided according to the solution to be applied (n = 10): CLX: 2% chlorhexidine (passively applied for 60 s) and NT (no treatment). A self-etching adhesive system was applied according to the manufactures instructions, with composite restorative placed on the dentin surface. After 24 h, dentin–resin blocks were sectioned into beam-shaped specimens that were submitted to microtensile bond strength testing either immediately or after six months of WS. Data were submitted to three-way ANOVA (α = 0.05). Bond strength values for the deep dentin group were significantly lower than those observed for superficial dentin (SD) (p = 0.002), whether chlorhexidine solution had been applied or not. There was no statistical difference in bond strength for specimens tested after 24 h and 6 months of WS. The application of chlorhexidine did not affect immediate and long-term bond strength to dentin. Bond strength in deep dentin was lower than in SD. [ABSTRACT FROM PUBLISHER]

The aim of this study was to evaluate the microtensile bond strength of two all-in-one self-etch adhesives applied to sound and caries-affected dentin with four different application techniques. Forty extracted third molars with occlusal caries were randomly divided into four groups for G-Aenial Bond and S3 Bond: (1) according to manufacturer's instructions; (2) with acid etching before applying adhesives; (3) doubling adhesive application time; and (4) doubling adhesive coating. Teeth were sectioned to obtain 1-mm- ± 0.2-mm-thick dentin sticks and subjected to a tensile force. For G-Aenial Bond, doubling the time and application of two consecutive coats produced significantly higher strength than that obtained by following manufacturers' instructions and acid etching application to sound dentin. Prior acid etching and application of two consecutive coats to caries-affected dentin generated significantly higher bond strength than that using other techniques. For S3 Bond, there was no significant difference between application techniques in caries-affected dentin. For sound dentin, double-time application of S3 Bond produced significantly higher strength than application according to the manufacturers' instructions. Compared to the application according to manufacturer's instructions, acid etching before applying adhesives, doubling application time, and doubling the coating had a positive effect on bond strength to caries-affected dentin for all-in-one adhesives. [ABSTRACT FROM PUBLISHER]

Application of 1% hydrofluoric acid (HFA) to improve the repair bond strength of a microhybrid (Z250; 3 M/ESPE) and a nanofilled dental composite (Supreme XT, 3 M/ESPE) was investigated. Aged composites were etched using 1% HFA for 10, 30, or 60 s. Negative (non-etched) and positive (10% HFA for 60 s) control groups were tested. The surfaces received a layer of a silane and adhesive (Single Bond 2; 3 M/ESPE). Cylinders of fresh composite (n = 15 per group) were built up and a shear bond strength test was carried out after water storage for 24 hr or 6 months. Surface topography was assessed using atomic force microscopy (AFM). For the nanofill at 24 hr, all etching regimens yielded higher bond strengths than the negative control. After 6 months, the negative and positive controls showed lower bond strength than 1% HFA for 30 s. For the microhybrid, the negative control generally showed lower bond strength at 24 hr, while all groups had similar results after 6 months. Only the positive controls showed lower bond strengths after 6 months. AFM analysis showed that the nanofill was more susceptible to acid-etch roughening. In conclusion, exposure to 1% HFA may improve the repair bond strength of dental composites. [ABSTRACT FROM PUBLISHER]

Purpose The aim of this study was to investigate the push-out bond strength (PBS) of resin-relined and non-relined glass fiber posts (GFP) luted to flared root canals. Material and methods Root canals of 80 bovine incisors were enlarged to obtain 40 mildly flared and 40 over-flared post spaces. Half of the specimens from each group had the GFP resin-relined, whilst the remainders were not relined. A further 20 root canals were minimally flared and restored with a non-relined GFP (control group). Posts were luted into the root canal space using dual-cure resin cement. Three slices were sectioned from each specimen: one from the coronal third and the others from the middle and apical thirds. PBS test was performed in a universal testing machine at a speed of 0.5 mm/min. Results Two-way ANOVA for repeated measures and Tukey’s test showed that PBS was affected by the root canal flare and relining procedure ( p <0.001). Relining significantly increased the PBS of GFP luted in roots with mildly flared canals when compared to those with excessive widening, regardless of the relining procedure. Relining GFP for over-flared canals had a PBS equivalent to that observed in the control group (minimally flared canal/non-relined GFP). PBS values were higher in the coronal third. No difference was found between the PBS values in the middle and apical thirds. Conclusions Depending on the extent of the root canal flare, relined fiber posts may outperform or at least perform as well as posts luted in minimally-flared canals. [ABSTRACT FROM AUTHOR]

The aim of the study is to evaluate the influence of surface-treatment methods with and without the use of a retention hole on the shear bond strength of a resin composite adhered to amalgam using an adhesive system. Amalgam specimens were divided into six groups. Group 1 (Bur) specimens were roughened with a diamond bur, Group 2 (Al2O3) specimens were sandblasted with a 50??m aluminum oxide powder, Group 3 (CoJet®) specimens were sandblasted with 30??m CoJet®Sand, Group 4 (Bur?+?Rh) specimen surfaces were prepared with a retention hole 1?mm in diameter and 1?mm deep and roughened with a diamond bur, Group 5 (Al2O3?+?Rh) specimens were also prepared with a retention hole and sandblasted with 50??m aluminum oxide powder, and Group 6 (CoJet®?+?Rh) surfaces were prepared with a retention hole and sandblasted with 30??m CoJet®Sand. Resin composite cylinders were bonded onto the amalgam surfaces using Xeno®IV, Optibond™ All-In-One, Clearfil™ SE Bond, Adper™ Single Bond Plus, and Scotchbond™ Multi-Purpose adhesive systems. In addition, silane (Monobond S) was used for Groups 5 and 6. The shear bond was determined and statistically analyzed using two-way analysis of variance andpost hocTukey’s tests (p???0.05). The surface treatment significantly affected the shear bond strengths of the adhesive systems. The shear bond strengths of Optibond™ All-In-One (2.661?±?0.48?MPa) in Group 1 and Scotchbond Multi-Purpose (3.818?±?0.98) in Group 4 were significantly higher than those of the other adhesive systems. Silica coating of the amalgam surface significantly improved the shear bond strength of the resin composites. The addition of a retention hole on the amalgam affects the bonding strength of the composite adhesion. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of surface treatment with Er:YAG and Nd:YAG lasers on resin composite bond strength to recently bleached dentin. A total of 120 bovine incisors were distributed into two groups: C- without bleaching; and B- bleached with 35% hydrogen peroxide. Each group was divided into three subgroups: N- without laser treatment; Nd- Nd:YAG laser irradiation; and Er- Er:YAG laser irradiation. The adhesive system (Adper Single Bond 2) was applied and composite build-ups were constructed with Filtek Supreme (3 M/ESPE). The teeth were sectioned to obtain dentin–resin sticks (1 × 1 mm2) and tested by microtensile bond testing. The bond strength values in group B, subgroup N (16.1 ± 3.5 MPa) presented no significant difference compared with group B, subgroup Er (14.7 ± 6.1 MPa). Group C, subgroup N (26.8 ± 7.4 MPa) presented no significant difference compared with group B, subgroup Nd (28.8 ± 5.6 MPa). Group C, subgroup Nd (36.1 ± 7.9 MPa) presented a significant increase in bond strength compared with the other groups. The Er:YAG laser did not influence the bond strength of bleached specimens, and the use of the Nd:YAG laser on bleached specimens was able to reverse the immediate effects of bleaching, obtaining bond strength values similar to those of the control group. [ABSTRACT FROM PUBLISHER]

The aim of the present work is to study the effect of laser-induced surface patterning on the strength of adhesive joints. Laser ablation was carried out on aluminum alloy (AA6082-T4) and stainless steel (AISI 304) substrates using a pulsed ytterbium fiber laser (LaserPoint YFL 20P). The morphological and elemental modifications induced by the laser ablation were analyzed by means of surface profilometry, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). In addition, surface wettability was analyzed by means of the sessile drop technique. In order to assess the capability of laser ablation to improve mechanical interlocking, cross-sectional areas of the samples taken across the interfacial region were probed under an optical microscope. Finally, mechanical tests were carried out on single-lap shear joints and the fracture surfaces were observed using the SEM. The obtained results showed that low power laser ablation can increase the strength of adhesive joints. [ABSTRACT FROM PUBLISHER]

Abstract: This study introduces a novel surface treatment (thermal silicatization) for bonding to zirconia ceramics. The method is based on the application of a solution containing silane, distilled water, and absolute ethanol, followed by heat treatment at 150°C for 1h and 600°C for 2h for deposition of a reactive siloxane network on the zirconia surface. The thermal silicatization was compared with traditional coupling agents for ceramic bonding (silane, zirconia primer, and/or adhesive), evaluating the shear bond strength of a dual-cured resin luting agent to yttria-stabilized zirconia. For the thermal silicatization method, two groups were tested: one group with silane applied to the ceramic (Sit) and another group with the application of silane and adhesive (SitA). Data were analyzed by ANOVA on ranks and Dunn's test (5%). The zirconia primer yielded higher bond strength compared with silane and/or adhesive. The combination of zirconia primer and adhesive generated higher bond strength than the primer alone. The group Sit showed higher bond strength than most of the groups while the bond strength of SitA had higher bond strength than all other groups. Deposition of a silicate layer on the zirconia surface was confirmed by x-ray energy dispersive spectroscopy. In conclusion, the proposed thermal silicatization method might promote the bonding of resin luting agents to dental zirconia ceramics. The proposed method is simpler and more cost-effective compared to other methods described in the literature as it could applied to the internal surface of zirconia frameworks using the same sintering protocol of the veneering ceramic. [Copyright &y& Elsevier]

Abstract: In this study the suitability of using the organometallic compound triphenyl bismuth (TPB) as a radiopacifier for dental adhesive resins was investigated. A model photocurable (di)methacrylate co-monomer was loaded with 0 (control), 5%, 10%, 15%, 20%, or 30% mass fraction of TPB. Viscosity of the monomer was assessed using an oscillatory viscometer. Polymer radiopacity was investigated using a phosphor plate digital system. Other fundamental polymer properties evaluated were: translucency parameter by spectrophotometry, degree of C=C conversion by infrared spectroscopy, flexural strength/modulus and work-of-fracture in 3-point bending mode, water/ethanol sorption and solubility, and shear bond strength to dentin. Data were analyzed using one-way ANOVA (homoscedastic data) or ANOVA on Ranks (heteroscedastic data) followed by Student-Newman–Keuls' test (5%). The phenyl rings of TPB were identified by peaks in the 700–800-cm−1 infrared area. Incorporation of ≥20% of TPB affected the co-monomer viscosity. Linear increase in radiopacity was associated with the increase in TPB concentration, although no significant differences were detected between 20% and 30%. Addition of TPB did not affect monomer conversion or dentin bond strength. Flexural properties were generally lower for materials with ≥10% of TPB. Polymer translucency was affected by TPB incorporation above 10%. Ethanol/water sorption was lower in TPB-containing materials, while solubility was higher. TPB may be a suitable agent to render dental adhesives radiopaque, although methods to improve the polymer strength might be necessary. [Copyright &y& Elsevier]

Abstract: The influence of diphenyliodonium hexafluorophosphate (DPI) on the mechanical properties and bond strength of resin cement to the intraradicular dentin was evaluated. A model BisGMA/TEGDMA-based luting composite containing camphorquinone and ethyl 4-(dimethylamino)benzoate was modified by incorporating DPI at 0 (control), 0.5, 1, or 2mol%. Flexural strength (FS) and modulus (E f) were evaluated by a 3-point bending test. The bond strength to dentin was evaluated by push-out testing of glass-fiber posts luted into bovine roots, which were sectioned into cervical, middle, and apical thirds. Polymerization stress (PS) was analyzed using photoelastic analysis. Data were statistically analyzed at p<0.05. No significant differences in FS were observed. The 2mol% group showed higher E f than the control and 0.5mol% groups. The control group showed higher PS than the 1 and 2mol% groups. The control group showed higher bond strength in the cervical region than the other groups. The use of cements with DPI might be promising for the luting of fiber posts due to lower stress generation at the bonding interface. [Copyright &y& Elsevier]

The aim of the present study was to evaluate the effect of natural (green tea (Camellia sinensis) GT) and synthetic (chlorhexidine-CLX) metalloproteinase inhibitors on the microtensile bond strength (µTBS) of an etch-and-rinse adhesive to dentin, after 24h and 6 months of water storage (WS). Thirty human dentin specimens were conditioned with 37% phosphoric acid for 15s, rinsed for the same amount of time and dried gently. They were then divided into 3 groups, according to the solution to be applied to the dentin surface (n=10): GT, 2% CLX, or NT (none, as control). CLX and GT solution (20μl) were applied for 60s and dried gently with absorbent paper. The adhesive system (Adper Single Bond 2, 3M ESPE) was then applied according to the manufacturer's instructions, and a 4-mm composite resin block was built. After 24h, at 37°C, resin–dentin blocks were sectioned into 1-mm2 sticks that were assigned into two µTBS test conditions: after being stored in water for 24h or after 6 months. Data were submitted to repeated-measures two-way ANOVA and Tukey's test, with a 5% significance level. The failure pattern was described in percentage terms. The results showed that the µTBS values in the NT group were significantly higher compared to the GT values. The application of CLX resulted in intermediate µTBS values, which were not statistically different from NT or GT. There was no significant difference between the µTBS values in the two time points of analysis for CLX and GT groups while the NT group showed a significant decrease over time. After 6 months of WS, all groups had µTBS values statistically similar among themselves. It can be concluded that in a short-term evaluation, chlorhexidine showed no interference on bond strength to dentin, while green tea did. After a long-term evaluation, both metalloproteinase inhibitors, chlorhexidine and green tea, were capable of maintaining bond strength stability. [ABSTRACT FROM AUTHOR]

This study evaluated the performance of different bonding tests on the bond strength of three adhesive systems to dentin. Forty-eight bovine incisors were used in the study, which were allocated in two groups according to the bond strength test performed: microtensile (µTBS) or microshear (µSBS). Also, each group was divided in three subgroups according to the adhesive system applied: Single Bond (SB), Prime & Bond (PB) and XP Bond (XPB) (n=8). The teeth were prepared according to each bond strength test protocol, and then the specimens were tested in an universal testing machine (EMIC). The data were submitted to two-way ANOVA (bond strength test and adhesive system type factors) and Tukey's post hoc test (α=0.05). The µTBS results were higher for all the adhesives when compared to the µSBS ones. Within the µTBS results, SB showed higher bond strength than PB and XPB, which showed similar adhesive performance among each other; within the µSBS results, all the adhesives presented similar bond strength values to dentin. The µTBS test detected differences between the adhesive systems evaluated; in contrast, the µSBS test was less discriminating in evaluating the adhesive performance of the materials tested. [ABSTRACT FROM AUTHOR]

Abstract: Unique design of self-etch adhesive monomers combines acidic functional group and double bond into a single molecule, which presents complexity as using the environmentally-sensitive photoinitiators in such a system. The objective of this study was to evaluate the kinetics of polymerization for self-etch adhesives cured with two different photoinitiators camphorquinone (CQ) and trimethylbenzoyl-diphenyl-phosphine oxide (TPO). Model self-etch adhesives contained bis[2-(methacryloyloxy)ethyl] phosphate (2MP) and 2-hydroxyethyl methacrylate (HEMA) (mass ratio of 2MP:HEMA=1:1). Different contents of water from 0wt% to 60wt%, or NaOH from 0.2wt% to 2wt% were incorporated to the system. The adhesives were cured using quartz–tungsten–halogen (QTH) or light-emitting diode (LED) light curing units. The degree of conversion (DC) and polymerization rate (PR) of the model self-etch adhesives were determined using ATR/FT-IR with a time-based spectrum analysis. TPO generally outperformed CQ/4E to initiate the self-etch adhesives when using the QTH curing unit. In addition, the DC of the TPO-initiated adhesives displayed increasing trend with water content, in contrast to a decreasing trend for the CQ/4E-initiated system. Furthermore, polymerization of the TPO-initiated system was independent of pH of the self-etch adhesives, whereas the DC and PR of the CQ/4E-initiated system were strongly influenced by the pH. As the LED curing unit was used, polymerization of both TPO and CQ/4E-initiated adhesives was greatly depressed. However, the DC and PR of the CQ/4E initiated adhesives could be improved by increasing pH of the system. In summary, the TPO-initiated system exhibits superior polymerization performance to the CQ/4E system as well as water-favorable and pH-independent features as using QTH curing unit. [Copyright &y& Elsevier]

Abstract: The aim of this study was to evaluate the influence of an iodonium salt on the immediate and long-term microtensile bond strength to dentin of an experimental dental two-step, self-etching adhesive system. A model dental adhesive resin was formulated using bisphenol A glicidyl dimethacrylate (Bis-GMA), triethylene glicol dimethacrylate (TEGDMA), and hydroxyethyl methacrylate (HEMA), which was polymerized using four combinations of photo-initiators and coinitiators. A group using only camphorquinone (CQ), two binary systems (CQ and ethyl 4-dimethylamine benzoate (CQ+EDAB), CQ and diphenyliodonium hexafluorphosphate (CQ+DPIHFP)) and a ternary system (CQ+EDAB+DPIHFP) was investigated. Clearfil SE Bond (CSEB) was used as a commercial reference. Bond strength to bovine dentin was assessed through microtensile bond tests measured in MPa in a universal testing machine. The beam specimens were stored in distilled water at 37°C for 24h and 1 year. Two-way ANOVA and Student–Newman–Keuls'' post-hoc tests were used to compare means of groups (α=5%) and failure modes classified under magnification. After 24h, the ternary system showed a bond strength similar to that of the binary system CQ+EDAB and the commercial material. After 1 year of storage, the μTBS values of the group CQ+EDAB+DPIHFP showed a bond strength significantly higher (p<0.05) than those of the CQ, CQ+DPIHFP, and CQ+EDAB groups and no difference from that of the CSEB group. The ternary photo-initiator system with iodonium salt maintained increased bond strength to dentin of model self-etching adhesive systems after 1 year of aging. [Copyright &y& Elsevier]

Abstract: Octa-(ethyl octadeca-10,13 dienoamide) silsesquioxane or bio-POSS was used in the fabrication of polyethylene (PE)/bio-POSS blends by melt mixing. These PE/bio-POSS blends were applied to paperboard by compression moulding coating. The T-peel test was used to determine the adhesion of the blends to paperboard. A FTIR-ATR spectroscopic study was performed to identify the interfacial interaction between PE/bio-POSS blends and paperboard. The T-peel test showed that the adhesion of PE to paperboard was enhanced when there was less than 10wt% of bio-POSS in the blends. The best adhesions were achieved at 5wt% and 3wt% bio-POSS, coated at 200°C/20°C and 300°C/20°C, respectively. The increase in adhesion strength was attributed to the contribution of mechanical interlocks and probable interfacial interaction between amide groups of bio-POSS and hydroxyl groups of paperboard, as specified by FTIR-ATR. Bio-POSS content above 10wt% led to a decrease in adhesion between PE/bio-POSS blends and paperboard because the melt flows and mechanical properties of the blends were dramatically decreased. [Copyright &y& Elsevier]

Abstract: Objectives: The aim of this study was to evaluate the influence of storage time on the bond strength of self-etching adhesive systems to artificially demineralized dentin submitted to application of a papain-based chemical mechanical agent for carious tissue removal. Materials and Methods: Twenty-four blocks of human coronal dentin were randomly divided into 2 groups: (1) restored with a two-step self-etching adhesive system (Clearfil SE Bond); (2) restored with a one-step self-etching adhesive system (One-Up Bond F Plus). After artificial caries induction, the specimens were treated with papain-based gel, received an application of the adhesive system according to the respective group, and blocks of microhybrid resin composite measuring 5.0mm high and 5.0mm wide were fabricated incrementally on the tooth, which would later be cut to obtain sticks with a bond area of around 1mm2, for use in the microtensile tests. After this, half of the sticks obtained from each tooth were submitted to the microtensile test 24h later, while the other half were stored in water, in an oven at 37°C for a period of 180d. The specimens were submitted to the microtensile test in a Universal Test Machine at a speed of 0.5mm/min. The surfaces of the fractured test specimens were examined visually under a stereoscopic loupe in order to classify the fracture type. After exploratory analysis of the data, the two-way Analysis of Variance (ANOVA) and the Tukey test were applied. The data on the fracture types were analyzed by the Exact Fisher test. Results: No statistically relevant differences were verified among the means of the microtensile bond strength values of the adhesive systems evaluated in the different storage times. Mixed and adhesive fractures types were observed for both groups. Conclusion: Storage time did not influence the bond strength of the two-step or one-step self-etching adhesive systems to artificially demineralized dentin submitted to application of a papain-based chemical mechanical agent for carious tissue removal. Both adhesive systems provided similar bond strength at different storage times. [Copyright &y& Elsevier]

Abstract: This study evaluated the effect of the concentration of acidic functional monomer on the dentin bond stability of a model two-step, self-etch adhesive system. Six self-etch primers were formulated using hydroxyethyl methacrylate (HEMA), 1,3-glycerol dimethacrylate phosphate (GDMA-P), ethanol and water. Different mass concentrations of GDMA-P were tested: 0, 15, 30, 50, 70 or 100% (primers labeled P0–100). The pH of the solutions was measured. The bonding resin was composed of (di)methacrylates. Bond strength to bovine dentin was assessed through a microtensile bond test. The beam specimens were stored in distilled water, at 37°C, for 24h, 6 months or 1 year. Data were statistically analyzed and failure modes classified under magnification. The increase in acidic monomer concentration was associated with an exponential decrease in pH (R 2 =0.999; P<0.001). All specimens debonded prematurely for the primers P 0, P 70 and P 100. After 24h, the bond strengths for P 50>P 30=P 15. After 6 months and 1 year, P 50=P 30>P 15. The bond strength after 6 months was similar to 24h for P 15 and P 50, but significantly lower after 1 year. P 30 showed no differences in bond strength over the 1-year storage period. A predominance of mixed failures was detected for all primers at 24h. After 6 months, P 30 and P 50 showed a predominance of adhesive failures. After 1 year, the predominant failure mode for all primers was cohesive within dentin. In conclusion, a mass fraction of 50% of phosphate monomer is a limit to be added to self-etch primers; a more stable longevity of the bonds was obtained with the primer with 30% of phosphate methacrylate. [Copyright &y& Elsevier]

Abstract: The effect of silane treatment on the push-out bond strengths of three different luting agents to fiber-reinforced composite (FRC) posts after thermocycling was evaluated. Sixty single-rooted human maxillary central incisors were sectioned below the cemento–enamel junction, and the roots were endodontically treated. RelyX Fiber Posts (size #2) were inserted using etch-and-rinse, self-etch, and self-adhesive luting agents (cementing agents). For half of the specimen in each group, the fiber posts were treated with a silane coupling agent. Bonded specimens were cut (2-mm-thick sections) and push-out tests were performed (crosshead speed, 0.5mm/min). Failure modes were evaluated using a stereomicroscope at original magnification ×40. For each luting agent the use of silane did not result in any statistically significant difference at any level of the root compared to those of the control groups except for Variolink II and RelyX Unicem luting agents in apical root section (p<0.05; one-way ANOVA). The post hoc analysis showed that regardless of the pre-treatment procedures, Variolink II achieved significantly higher bond strengths than Panavia F 2.0 and RelyX Unicem in all root sections (p<0.05). The use of a silane coupling agent had no influence on bond strengths depending on the luting agent used, whereas the type of luting agent (etch-and-rinse, self-etch, and self-adhesive) appeared to be a significant influence on the push-out bond strength values independent of the pre-treatment used. Therefore, pre-treatment of fiber posts with a silane coupling agent does not seem to be mandatory, which saves time in the clinical situation. [Copyright &y& Elsevier]

Abstract: Acacia mangium is a fast-growing dicotyledonous tree species and has become the dominating plantation in Malaysia. It was grown particularly as a raw material for veneer, pulp, and paper industries. The chemical properties test in this study showed that the A. mangium tree bark contains higher extractive content as compared to the wood portion (sapwood). Tannin extracts from A. mangium tree bark were found to be rich in phenolic compounds and had the potential to replace conventional phenol–formaldehyde (PF) adhesive used in the plywood manufacturing industry. Tannin adhesive (tannin–paraformaldehyde) prepared from A. mangium bark tannin by cross-linking with paraformaldehyde were used for bonding of Mempisang (Annonaceae spp.) plywood board. However, the resulting bonding strength using tannin adhesive was found to be only suitable for interior grade application. Further extension of its application for interior and exterior grade plywood could be achieved with addition of PF (co-polymerization with resol) during the production process. The optimized formulation of tannin adhesive consists of A. mangium solid extracts (90 parts), commercial PF (10 parts), and paraformaldehyde (3%). Results have shown that the plywood shear strength complies with the requirement for European norms EN 314-1 and EN 314-2:1993, which includes the dry test, cold water test, and the boiling test. [Copyright &y& Elsevier]

Abstract: This study concerns with the explanation of the wide range of adhesion strengths observed depending on the nature of substrate surface topography by linking macroscopic adhesion strength to microscopic energy-expenditure mechanisms during fracture. The dominant factors to which the adhesion strength of polymer–metal interfaces is attributed are investigated theoretically and experimentally. In an attempt to elucidate the effect of mechanical interlock on adhesion strength, micro-patterns were fabricated on metal surfaces as a designed surface topography. It was found that the molecular dissipation of the polymer in the vicinity of the interface is the major cause of the practical energy of separation. Furthermore, it is shown that loading mode controls the mechanical interlock effect, which is attributed to the fact that the stress distribution at the interface controls the deformation and failure characteristics of the polymer resin near the interface. Therefore, mechanical interlock promoted by adsorption provokes energy dissipation processes during fracture, which practically constitute the adhesion strength of a polymer–metal interface. The contribution of mechanical interlock to adhesion strength is systematically assessed by varying micro-pattern dimensions. The influence of the work of adhesion, cohesion and other dissipation energy on adhesion strength is examined by measuring each contribution to the total work of fracture. [Copyright &y& Elsevier]

A study of the effects of grit-blasting and plasma-spraying angles on the adhesion strength of an alloy (Tribaloy 800) that was plasma sprayed on a titanium-base alloy is reported. Five different spray and grit-blast angles were investigated: 45°, 55°, 65°, 75°, and 90°. The surface texture in different directions was characterized by the classic average roughness and by a fractal analysis number using a two-dimensional fractal analysis method. The grit residue was measured by an x-ray spectrometer. The study showed that the maximum adhesion strength was close to a 90° blasting and spraying angle. However, the grit residue reaches its maximum at a 75° blasting angle. From the image analysis of the interface in different directions, it was found that the nonperpendicular grit blasting produces an anisotropic surface. The fractal analysis method showed a rather good correlation with the blasting angle. However, no good correlation between the fractal number and the adhesion strength was found. [ABSTRACT FROM AUTHOR]

Electromagnetically assisted adhesive joining (EAAJ) is a novel hybrid joining technique combining the benefits of electromagnetic crimping and adhesive joining. This paper explores the possibility of creating an interference-fit tubular adhesive joint with improved strength and leak tightness. An acrylic-based structural Loctite 638 adhesive is used. Experiments are performed with and without (electromagnetic crimping) adhesives. Pull-out and compression test is performed for both joining techniques which has confirmed a significant improvement in joint strength with adhesives. A two-factor ANOVA analysis is also performed to calculate the contribution of adhesives and discharge energy over pull-out and compressive strength of the joint. An air leak testing setup is developed to investigate the leak tightness of the Cu-SS tube-to-tube Joint. Leak tightness is observed to be increased by ten times in the case of EAAJ compared to EMC. Macrographs have revealed no metallic bond formation. Deformation analysis is also performed to study the various zones of the samples. Micro-hardness is observed to be decreased for the adhesive joint in the adhesive zone. [ABSTRACT FROM AUTHOR]