Applied Adhesion Science最新文献

Peel plies can be used during the manufacture of fibre-reinforced plastics for two reasons: to protect the surface during transport and storing the parts as well as during subsequent work steps, such as adhesive bonding, the removal of the peel ply can result in bondable surface with required surface characteristics. However, the use of peel plies is not straightforward. It can be difficult to remove peel plies and a surface produced by a peel ply is altered in terms of roughness and elemental composition. In the present work, the influence of fluorine-based release agents on adhesive joining of carbon fibre reinforced composites is investigated. Within the scope of the screening, 14 fluorine-based release agents—ETFE release films, PTFE coated glass fabrics as well as fabrics made of PTFE fibres—were investigated. Preliminary studies (Meer, in: Deutscher Luft- und Raumfahrtkongress 2014, Augsburg, 2015) have shown that ETFE films have advantages in terms of adhesion. The study covers a number of aspects: the determination of the tear strength of the release agent by peel test; the determination of the element composition (XPS) and surface characteristics (SEM) before and after atmospheric pressure plasma pre-treatment, characterization the topology and the characterization of the adhesive strength by centrifugal adhesion test.

Biodentine? is currently and regularly used as a direct/indirect capping material and dentine substitute under a resin composite direct restoration. The present study investigated the influence of Biodentine? maturation time on its shear bond strength to a resin-based composite restorative material.

One hundred fifty PTFE tubes were divided into 2 groups (n?=?75), and each group of tubes was filled with a different substrate material (Biodentine? or GC Fuji IX glass ionomer cement). The tubes were subsequently divided into subgroups (n?=?25) that were used to test different substrate maturation times (early, 12?min; medium, 72?h; and delayed, 2?weeks). A resin-based composite restorative material was bonded to the substrates using a 3-step etch and rinse adhesive system (Optibond FL, Kerr), and the bond was tested for shear bond strength.

The Biodentine?/12-min group showed a very low shear bond strength of 2.796?±?2.704?MPa. The values for the Biodentine?/72-h and Biodentine?/2-weeks groups increased as the maturation time interval increased and were 7.986?±?2.100?MPa and 10.553?±?3.281?MPa, respectively. The differences between the Biodentine?/12-min group and the Biodentine?/72-h and Biodentine?/2-weeks groups are statistically highly significant (p?<?.001). The difference between the Biodentine?/72-h group and the Biodentine?/2-weeks group is statistically significant (p?<?.05).

Bonding with Biodentine? that has matured for 72?h results in a statistically significant increase in shear bond strength and yields a more clinically acceptable bond between the two materials.

Adhesively-bonded joints are widely used to join structural components. The most common joint types are single-lap joints (SLJ), double-lap joints (DLJ), stepped-lap joints and scarf joints. Several factors influence the behaviour and strength of an adhesive joint, namely the type of adhesive (brittle or ductile, strong or weak) and joint geometry. One of the most important parameters that affects the joint strength is the overlap length (L_O). A comparative study that involves several joint geometries and uses adhesives with different characteristics was carried out to check which type of adhesive is most suitable for a particular joint geometry. For this purpose, SLJ, DLJ, stepped-lap joints and scarf joints were chosen for testing with three adhesives. The experimental results were compared with numerical results obtained from Abaqus^? using an integrated cohesive zone modelling module. Initially, a stress analysis was carried out to compare the different joint geometries. With this work, it was concluded that the optimal joint type significantly depends on the type of adhesive used, such that less strong and ductile adhesives are more suitable for joint geometries that exhibit large stress variations, while stronger but more brittle adhesives are recommended for joint geometries with more uniform stresses.

It would not be an exaggeration to say that adhesive joints have been an essential part of the construction industry for several decades now. However, a substantial disadvantage of bonded joints are the very strict requirements for adherence to the technological procedures defined by the manufacturers of assembly systems. Even a slight deviation from the recommended application steps can have a significant effect on the integrity of the entire system. In the research, five of the most common types of failure to comply with technological procedures in the realization of facade cladding were selected. The aim of the research project was to determine the extent to which a failure to adhere to technological procedures during facade construction can influence the effectiveness of the bonded joint. In construction practice, it is quite common during the implementation of a project that there are failures to comply with multiple requirements, or deviations from the prescribed procedures. For this reason, not only individual types of failure to comply with technological procedures were tested, but also their combinations. Altogether, 31 combinations of selected types of failure to comply with technological procedures were tested on one type of cladding. The adhesive joint was tested for shear strength and the adhesion of the adhesive to the substrate on a total of 352 samples. The results of the tests clearly confirm the hypothesis that failure to comply with technological procedures has a significant effect on the effectiveness of bonded joints. It is mainly the different combinations of failure to comply with technological procedures where the bonded joint loses effectiveness in the order of tens of percentage points.

With the increasing use of structures with adhesive bonds at the industrial level, several authors in the last decades have been conducting studies concerning the behaviour and strength of adhesive joints. Between the available strength prediction methods, cohesive zone models, which have shown good results, are particularly relevant. This work consists of a validation of cohesive laws in traction and shear, estimated by the application of the direct method, in the strength prediction of joints under a mixed-mode loading. In this context, scarf joints with different scarf angles (α) and adhesives of different ductility were tested. Pure-mode cohesive laws served as the basis for the creation of simplified triangular, trapezoidal and exponential laws for all adhesives. Their validation was accomplished by comparing the numerical maximum load (P_m) predictions with the experimental results. An analysis of peel (σ) and shear (τ) stresses in the adhesive layer was also performed to understand the influence of stresses on P_m. The use of the direct method allowed obtaining very precise P_m predictions. For the geometric and material conditions considered, this study has led to the conclusion that no significant P_m errors are incurred by the choice of a less appropriate law or by uncoupling the loading modes.

When someone joins large structural components, the importance of the joining technology increases. Well-known joining processes such as welding and classic adhesive bonding reach their limits with respect to cycle times and tolerances. A new two-component polyurethane injection process based on the reaction in mold technology, offers an alternative and has the potential to reduce costs and compensate tolerances. The objective of this paper is to characterize and evaluate this process for potential applications so that it is possible to set the parameters as necessary. The example that was chosen for this research is the battery housing for electric vehicles. The advantage that this process does not only join the parts within seconds, but also will seal or fill long gaps if necessary, makes it particularly interesting for the industry. Classic adhesive technology applies the adhesive on one part, then takes the second part for the joining process, grouts the adhesive to a defined gap and afterwards, it still has to cure in a geometrically-defined tool. The PUR injection process fixes the two components in a tool with a defined gap and afterwards, injects the PUR that then reacts in the gap and joins the two parts within seconds. The adhesion and as well the rheology decreases with an increase in crosslinkings. These two parameters are therefore described relative to time and temperature. A steep increase in viscosity is detected after just a few seconds. With higher adherend temperatures the increase in viscosity appears earlier and steeper. The property for adhesion to the surface is decreasing the longer the PUR takes to hit the surface. These dependencies are described in this paper to develop a reproducible application process with a battery housing for electric vehicles as a case study.

This study aimed to identify diagnosis and restorative practices of non-carious cervical lesions (NCCLs) by a group of Brazilian dentists from the State of Rio de Janeiro. After ethical approval, a questionnaire was sent for a group of dentists registered at the Regional Council of Dentistry of the State of Rio de Janeiro (CRO-RJ, Brazil) and the answers were collected in a period of 15?days. The questionnaire considered training experience and attendance profile, diagnostic attitudes and restorative practices for direct restorations of NCCLs. The data were presented in a descriptive way and Chi-square tests (95% significance) were used to verify possible relations between dentists training/attendance profiles and NCCLs diagnosis/restorative attitudes. Most part of dentists considered the etiology as multifactorial and seek to distinguish the different types of NCCL, but only a minority respond to use auxiliary methods for diagnosis. Cotton-roll is the most used method for moisture control and 51.6% do not use gingival retraction/separation techniques. Two-step total-etch adhesive systems and hybrid/microhybrid composite resins were the most commonly refereed materials for direct restorations. Only 8.3% considered that restorations can last for a period of more than 5?years in clinical service. There was significant relation between remuneration and the type of isolation (p?=?0.038) and also with gingival retraction/separation techniques (p?=?0.043). It can be concluded that (a) the majority of the respondents revealed to seek distinguishes among the different types of NCCLs, but only a minority use auxiliary methods to diagnosis; (b) the form of remuneration influence the attitudes regarding the isolation method; (c) the two-step total-etch adhesive systems are the most used to restore NCCLs, (d) and that for the most part of the respondents the restorations of NCCLs made with resin composites do not last for more than 5?years.

Assess the effect of applying a low viscosity resin before placing ceramic restoration with two different luting agent.

Twenty slices from IPS e.max CAD (Ivoclar Vivadent) were fired and assigned to 5 treatment surface groups; E: hydrofluoric acid (HF); E/S: HF-etching?+?silane (20?s); E/S+: HF-etching?+?silane (60?s); S: silane (20?s); S+: silane (60?s). Before building the cylinder with regular or flowable composite resin for the SBS test, half of each treatment surface group received adhesive (Optibond FL bottle #2), and the other half no adhesive. The SBS test was performed after 24?h. Statistical analysis was performed using multifactorial analyses of variance Two-way ANOVA. The Tukey HSD test was used to test the average values of all groups. The significance level adopted in all analyses was?≤?0.05 (p?<?0.05).

Groups E/S and E/S+, with flowable?+?adhesive and E/S with regular composite resin?+?adhesive, showed the highest SBS values (22.05, 18.91 and 21.06?MPa respectively), followed by group E with or without adhesive, for both luting agent. The lowest bond strength was observed when the silane was applied alone, independent of the adhesive coat and luting agent (0.65–5.55?MPa). When the adhesive was omitted, flowable presented high bond strength compared to composite resin in groups ES and ES+.

The low viscosity resin in the etched and silanized ceramic surface is important to obtain high SBS values.

Bonding of automotive glass is generally performed with 1C PUR adhesive on a primed ceramic frit or naked glass surface. The aim of this research was to replace the chemistry of the primer with an atmospheric pressure plasma treatment (APPT) with compressed air for cleaning and activation directly before bonding. Characterization of the glass surface was performed with surface energy through contact angle, XPS, TOF-SIMS and adhesive peel bead test. The results show that APPT treatment can clean the surface, improve the wetting, improve the bonding but reduce the number of non bridging oxygen for the adhesive to bond to. The highest measured spot temperature of the glass during APPT was measured up to 270?°C, but the temperature was depending on process parameters. A reduction in non bridging oxygen was also seen during heating of the reference glass at 100?°C. A further reaction was seen when measured after a 550?°C heating. A modified APPT treatment with deionized water as precursor was used. The results show that the APPT with water does not lower the level of non bridging oxygen and the bonding was further improved.

The purpose of this study was to investigate whether different surface treatments, executed before and after the sintering process, affect the surface characteristics (roughness and morphology) and shear bond strength of computer-aided design–computer-aided manufacturing (CAD–CAM) milled zirconia luted with self-adhesive resin cement onto human dentin. Sixty-four rectangular zirconia slabs (6?×?8.5?×?2.3?mm thickness) were prepared using the CAD–CAM system and randomly distributed into two groups according to the moment of treatment, before and after sintering, and four subgroups according to the surface treatment (n?=?8): C (untreated; control), AO (aluminum oxide air abrasion), GB (glass beads air abrasion), and HA (etching with hydrofluoric acid). The samples were evaluated using a confocal laser microscope to assess the surface roughness and morphology. For the shear bond strength test, the milled zirconia was cemented onto dentin slabs using self-adhesive resin cement and submitted to the test in a universal testing machine. Data were submitted to a two-way ANOVA and Tukey test (p?<?0.05). The surface roughness was always higher for the samples treated before sintering (highest roughness in the GB group). When treatment was employed after sintering, there was no difference between the subgroups. The shear bond strength analysis showed that the adhesion was greater when the treatment was employed after sintering, where groups AO, HA, and GB showed similar bond strength, higher than group C. Thus, it is concluded that regardless of the treatment performed, the bond strength is greater when zirconia is treated after sintering, while the surface roughness is greater before sintering.