International Journal of Adhesion and Adhesives最新文献

The objective of this study was to investigate a new silane-containing self-adhesive resin luting cement with both shear bond strength and contact angle studies to determine if silane in a resin cement would chemically bond to a lithium disilicate surface. The silane-containing cement, Panavia SA Cement Universal (Kuraray, Tokyo, Japan) was tested against a control case where a traditional silane treatment was paired with resin-luting cement, Duo-Link Universal (Bisco Inc., Schaumburg, IL, USA) with immediate shear bond strength testing on both polished and etched lithium disilicate, as well as after thermocycling. It was determined that micromechanical retention provided a substantial contribution to bond strength. However, after an aging study with 20,000 thermocycles and then storage for 6 months in 37 °C water, the silane-containing, self-adhesive resin cement significantly decreased in shear bond strength when compared to the control. From contact angle studies, while it was shown that the paste containing the silane did effectively increase hydrophobicity of the treated lithium disilicate surface, it required over 3 h contact time, which was not representative of clinical use.

The recommended 15-s acid etching time expands the enamel surface and facilitates the infiltration of restorative materials. Because of this clinical advantage, 15 and 30 s have become the most prevalent acid etching times in recent years. This study aimed to evaluate the effects of conventional and self-adhesive flowable composites (SAFCs) that were etched for different durations on primary molar teeth. Teeth were divided into eight groups (n = 16) and restored either with Vertise™ Flow and orthophosphoric acid or with Conseal F and orthophosphoric acid for 15, 30, 45, or 60 s. Then, the specimens were subjected to shear stress at a cross-head speed of 1 mm/min until the bond failed. After conducting the microshear bond strength (μSBS) test, failure modes were analyzed using scanning electron microscopy at 80 × magnification. Statistical analysis was performed using Independent sample T-tests and other T-tests (p < 0.05). According to the μSBS results, a statistically significant difference was observed among all groups (p < 0.05). Additionally, there were statistically significant differences between both restorative materials after etching for 15 s (p = 0.011; p < 0.05) and 60 s (p < 0.001; p < 0.05). While adhesive-type fractures were mostly observed in the SAFC groups, mixed-type fractures analyzed by scanning electron microscopy were determined to be relatively common in the Conseal F groups. An etching time of 15 s for primary tooth enamel was recommended instead of 60 s for all fissure sealants. In addition, the application of Vertise™ Flow after 15 s of acid etching was preferred over the application of Conseal F.

The growing market demand for compact and precisely-designed polymeric products has raised challenges during the demolding stage of manufacturing. An increased contact area between the product and the mold increases adhesion, which reduces dimensional stability and aesthetics. Conventional solutions like surface roughness improvement or release agent coatings suffer from reduced productivity and impurity-related issues affecting mechanical properties. To address these challenges, we imparted the semi-permanent demoldability to a stainless steel (SUS) mold by polymerizing stearyl methacrylate monomer on its surface using a surface-initiated solution polymerization technique. The polymerization state was confirmed through Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The demoldablity was investigated using the appropriately-designed lap shear tests to simulate the demolding stage of epoxy resin-filled SUS mold to ensure sufficient performance compared with the neat and commercial release agent (RA) treated molds, and durability of the demoldability was confirmed via repetitive single-lap shear tests simulating the molding and demolding processes. The surfaced polymerized mold exhibited excellent demoldability with 96.5 % improvement over the neat one, and showed excellent durability over 5 repeated molding cycles, while the commercial RA showed significant degradation of demoldability. Furthermore, the mechanism of demoldability enhancement using the proposed surface polymerization was investigated by characterization of the surface dewetting pattern and contact angle measurements of the epoxy resin on the modified mold surface.

Fluid catalytic cracking (FCC) waste catalysts produced by petroleum cracking contain many harmful substances, such as heavy metals, and improper treatment can lead to environmental pollution. To solve this problem, this study investigated four types of FCC (LM, SH, A, SL) waste catalyst as a substitute filler for limestone mineral powder and examined their interactions with asphalt and fillers. The X-ray fluorescence (XRF), scanning electron microscope and specific surface area tests were conducted to compare the performance of FCC waste catalyst and fillers. Meanwhile, the effects of FCC waste catalyst on asphalt mastic composed of limestone mineral powder and asphalt were evaluated using surface energy, interaction parameters, and FTIR. Results show that there is little difference in the main components of the four waste FCC catalysts and limestone mineral powder. However, the surface roughness and specific surface area of the FCC catalysts are significantly greater than those of limestone. Moreover, the addition of FCC waste catalyst can improve the adhesion of asphalt with fillers and aggregates, and significantly enhance the interaction capabilities between the filler and the base asphalt, especially for SH. FTIR analysis confirms that the aforementioned improvements are achieved through physical interactions. This study reveals the effects of different FCC waste catalysts on asphalt mortar, and provides a theoretical basis for promoting the practical application of FCC waste catalysts in road engineering.

Background/purpose

To evaluate the shear bond strength (SBS) of nanoceramic hybrid CAD/CAM blocks with two bulk-fill composites in deep margin elevation following different surface pretreatments.

Materials and methods

Forty cylindrical-shaped samples (3 mm diameter × 4 mm height) were prepared from each group of bulk-fill resin composites (BRC) (SonicFill 3/SF, VisCalor bulk/VS), and 80 samples (14.5 mm × 7.2 mm × 2 mm) were sectioned from Grandio Block. Specimens of each BRC were assigned to two subgroups, and surfaces of one group were treated with a tribochemical silica-coating. The CAD/CAM block sample surfaces were treated with Al₂O₃ particles. CAD/CAM block and composite samples were luted using dual-cure universal resin-based cement (Bifix QM). Following immersion in distilled water for 24 h, the samples were divided as immediate and test groups. The test group was subjected to thermocycle (5–55 °C, 10,000 cycles). The SBS of the resin-based cement between the blocks and BRC was tested on a universal testing device until failure. Failure type was determined using a stereomicroscope. The roughening pattern was evaluated with SEM. Statistical analysis included Shapiro Wilk, Generalized Linear Models, and Fisher's Exact tests (P < 0.05).

Results

No statistically significant difference was found between the mean SBS values according to deep margin elevation materials and surface pretreatment (P > 0.05). Aging procedure resulted in a statistically significant difference between the mean SBS values (P < 0.001). While the mean SBS value was 33.7 ± 7.9 MPa in immediate group, it was calculated as 22.6 ± 6.3 MPa in test group following thermocycle.

Conclusion

In terms of SBS, both bulk-fill resin composites performed similarly. Although higher SBS values were obtained with tribochemical silica-coating, the adverse effects of thermocycling on bonding could not be prevented.

Rubber-metal bonding interface prone to adhesive failure. Cohesive zone model (CZM) is widely used in numerical simulation analysis of fracture of interfacial mechanics. In this paper, the traction-separation curve of the bonding surface of vulcanized rubber-metal specimen was obtained by tensile shear test and dumbbell rubber uniaxial tensile test. Then, the influence of shear strain of rubber itself was removed by numerical simulation of tensile shear of rubber, so as to identify the CZM parameters of rubber-metal interface.On this basis, a numerical model of the cohesive force of vulcanized rubber-metal was established, and the stress distribution, variation and damage evolution of the interface along the shear direction were analyzed microscopically. The initiation and propagation of cracks are explained and compared with the failure process and phenomenon of the test interface. The traction-displacement relationship curve was analyzed macroscopically, which was consistent with the traction-displacement relationship curve obtained by the experiment, and the error is less than 5 %. The CZM could accurately express the interface mechanical relationship of the experimental specimen. In addition, the influence of the width and length of the bonding interface on the mechanical properties of the bonding is also analyzed. With the increase of the width or length of the bonding interface, the maximum traction force increases linearly, but the relative displacement value of the initial bonding failure remains unchanged, and the length of the bonding interface has a more significant effect on the maximum traction force. The results show that the cohesive zone model can accurately and effectively analyze the shear failure of the vulcanized rubber-metal bonding surface, which provides a reference for the study of the failure of the bonding surface of other elastic composites.

Objective

This study evaluated the effect of 2% inositol hexaphosphate (IP6) and 10% polyacrylic acid (PAA) on dentin surface micromorphology, matrix/mineral ratio, microhardness, and resin−dentin shear bond strength (SBS) of a self-adhesive restorative material (Surefil™ One; Dentsply Sirona, Konstanz, Germany).

Materials and methods

Human permanent molar mid-coronal dentin discs were either not treated (control), conditioned with 10% PAA (Dentin Conditioner, GC, Tokyo, Japan) for 20 s, or etched with 2% IP6 for 20 s. Dentin surface micromorphology (etching pattern), matrix/mineral ratio, and microhardness were characterized by a scanning electron microscope (SEM), a confocal Raman microscope and a microhardness tester using the Vickers indenter, respectively. Sound molars were cut flat, mounted, surface treated and restored with Surefil™ One, Dentsply. The shear bond strength (SBS) was evaluated using a universal testing machine at 24 h and after 10k thermo-cycles. The failure modes were assessed. One-way and two-way analysis of variance (ANOVA) followed by the Tukey's multiple comparisons test was used for the statistical analysis.

Results

IP6 etching resulted in a more aggressive and uniform etching pattern compared with PAA. The mineral/matrix and Vickers microhardness of IP6-etched dentin were significantly less than those of PAA-conditioned dentin. IP6 etching significantly improved the resin−dentin SBS compared with the control group (no treatment) at 24 h and after thermo-cycling. Adhesive failures were the most predominant in all study groups.

Conclusion

Inositol hexaphosphate acid etching deteriorated dentin microhardness and resulted in substantial demineralization, however, it eliminated the dentin smear layer completely and created marked micromorphological alteration at dentin surface, significantly increasing the resin−dentin SBS of a self-adhesive restorative material.

Moisture ingress into adhesive joints is known to reduce bond strength. The strength loss due to moisture is attributed to two primary causes. The first is the degradation of the adhesive layer, which progresses relatively slowly. The second is the reduction in the interfacial strength between the adhesive and the adherend, which is more difficult to predict. The degradation behaviour of interfacial strength varies depending on the adherend type. Therefore, the effect of water penetration on three open-faced steel and magnesium alloy specimens bonded with one-component epoxy adhesives was investigated. The open-faced specimen had no adherend on one side, and water penetrated at a high speed from the open side. The saturated water absorption state was reached faster in this specimen, which allowed the rapid confirmation of degradation after water absorption. To reduce test time, the specimens were examined in hot water at 87 °C. Initially, cohesive failure in adhesive layers occurred for the steel specimens and the strength decreased with time. Prolonged immersion resulted in progressive corrosion, and the fractures within the corrosion layer began to mix. For magnesium alloy plates, immersion in hot water caused immediate adhesion failure and, simultaneously, a significant reduction in the adhesion strength. When closed-faced specimens (i.e. normal specimens) were used instead of open-faced specimens, a sequential transition was observed from cohesion to adhesion failure with immersion from the edge.

An integrated strategy based on design of experiments (DoE) and multivariate regression was carried out to produce an optimized surface functionalized nanoclay (Mt–SH) with potential mucoadhesive properties. A mercaptosilane was grafted in montmorillonite in order to immobilize thiol groups (–SH) on the clay. The functionalization was confirmed by IR, TGA, XRF and XRD analyses. Five variables involved in the synthesis were optimized in order to maximize two responses: mass of functionalized nanoclay and amount of thiol groups attached in the clay surface. This optimization was performed by a two–step DoE strategy using Plackett–Burman and Box–Behnken designs. The five variables and two responses were simultaneously calibrated in a single ANOVA–validated PLS regression model. Analyzing scores, loading and surface response plots, the main processing variables, interactions and quadratic terms were found achieving the optimal processing conditions for the synthesis. The quadratic model (R² > 0.8589) predicted an optimized functionalized nanoclay of mass 3.29 ± 0.13 g of Mt–SH with 19.65 ± 0.78 μmol –SH per g Mt–SH (P < 0.05). The optimized Mt–SH was evaluated by in vitro and in situ mucoadhesion assays with porcine mucin and fresh intestinal mucus by using rheometry. The complex viscosity showed an increase of ∼54-fold higher compared to the unmodified Mt, and ∼12.8-fold increase in the elastic modulus, which indicates a more resistance to elastic deformation probably due to an increase in cross-linking points between Mt–SH and mucus. The formation of disulfide bonds between thiol groups from Mt–SH and glycoproteins in the mucin could be a reasonably explanation which shows a correlation respect other thiolated materials which show the same mucoadhesion properties. These results could project this functionalized silicate material as a potential mucoadhesive prospect for pharmaceutical applications.

Performance of the waterproofing adhesive layer played a critical role for governing duration of bridge deck paving system due to harsh service conditions. To develop a new type of modified bitumen suitable for the layer between bridge deck and overlaid asphalt, this study investigated the performance of composite modified bitumen (CMB) integrated with desulfurized crumb rubber (DCR) and SBS modifier. The influence of DCR and SBS additive on rheological behavior, high-temperature performance, low-temperature cracking resistance, and adhesive performance of CMB was investigated by adopting various experimental tests, which including penetration, ductility, softening point, Brookfield viscosity, dynamic shear rheometer (DSR), bending beam rheometer (BBR), and bonding strength. The high-temperature stiffness and low-temperature flexibility of CMB was improved after composite modification, which in turn contributed to the shear and cracking resistance. The black diagram indicated that the formation of polymer network in the CMB improved the viscous flow resistance and maintained elastic response at high in-service temperature. The bonding strength and moisture stability of the composite bitumen-concrete interface were enhanced, with the properties exceeded the commercial SBS modified bitumen. The CMB binders R18S2 and R18S3 presented good performance and can be used for waterproofing adhesive layer as a substitute of the commercial SBS modified bitumen.