The three-fibre method for measuring glass fibre to resin bond strength

This paper presents a method developed to measure the bond strength of a fibre/resin bond. Equipment has been developed to enable the test to be carried out in a normal tensile testing machine, and the results to be followed by scanning electron microscopy. Bond strengths obtained by this method are in agreement with earlier results. There are, however, some problems related to the method, including reproductivity of the test, determination of the degree of polymerization of the resin and the use of very thin fibres. However, the method has been proved a very quick and relatively accurate indicator of the strengths of fibre/resin bonds.     

The effect of matrix composition on fibre/matrix interfacial bond shear strength in fibre-reinforced mortar

The effects of factors associated with the composition of the matrix, i.e. curing conditions and time and mix proportions, on the shear strength of the interfacial bond between steel fibres and a cementitious mortar matrix have been examined experimentally using a single-fibre pull-out test technique. The experimental results indicate that bond shear strength increases significantly with an increase in matrix curing time and, for specimens with the fibre axis perpendicular to the direction of casting and compaction of the matrix, with a decrease in the proportion of water by weight in the matrix mortar. This latter effect is attributed to bleed water gain under the embedded fibre, as it is not observed in specimens with the fibre axis parallel to the direction of casting and compaction of the matrix. Furthermore, the results indicate that there is no correlation between interfacial bond shear strength and matrix mortar compressive strength.     

Influence of different surface treatments on zirconia/resin shear bond strength using one-bottle universal adhesive

ABSTRACT

This study was designed to evaluate the effect of different treatments on the zirconia/resin shear bond strength (SBS) using commercial one-bottle universal adhesive. Zirconia discs with different surface treatments (blank control; airborne-particle-abrasion; glazing) were bonded to the bovine enamel surfaces using one-bottle universal adhesive. All specimens were tested for SBS (MPa) before and after 10000 thermocycles. Statistically analysis were conducted by using one-way analysis of variance and multiple-comparison least significant difference tests (α = 0.05). Airborne-particle-abrasion group showed higher SBS (36.19 ± 11.86) than control group (14.98 ± 5.90) and glazing group (10.63 ± 5.39) (p < 0.05). After thermocycling test, the SBS significantly decreased for control group (8.84 ± 2.55) and glazing group (6.18 ± 2.78) while not for airborne-particle-abrasion group (41.5 ± 7.95). One-bottle universal adhesives combined with airborne-particle-abrasion showed quite high SBS of zirconia/resin, which was appropriate for bonding of zirconia restoration.     

Effects of functional groups and surface roughness on interfacial shear strength in ultrahigh molecular weight polyethylene fiber/polyethylene system

Corona discharge treatment was conducted for ultrahigh molecular weight polyethylene (UHMWPE) fiber. The functional groups and surface roughness of the polyethylene fiber surface were determined by an X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The interfacial shear strength of UHMWPE fiber with HDPE film was determined by microbond pullout method. The interfacial shear strength increased by corona treatment. Then, the effect of the chemical and physical factors on the interfacial shear strength was discussed based on the results of multivariate regression analysis. The results indicated that the contribution of functional groups and surface roughness to the interfacial shear strength was expressed as 50 and 50%, respectively. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 243–249, 1999     

Study of the interfacial adhesive strength of a heat-shrinkable multilayer film

A heat-shrinkable multilayer film is widely employed as labels of plastic bottles. A new heat-shrinkable multilayer film without an adhesive layer was designed in this study. The interfacial adhesive strength between the layers was controlled to avoid layer separation. We assumed a polyethylene terephthalate glycol-modified (PETG)/styrene-co-butadiene block copolymer/PETG shrinkable film substitute as the general poly(ethylene terephthalate) (PET)/polystyrene/PET shrinkable film. The interlayer adhesive strength between the layers was retained for industrial utilization even after drawing. Additional polybutadiene (PB) infiltrated the butadiene layer in the microphase-separated structure. Further addition of PB could not infiltrate the butadiene layer. The excessive PB contents coexisted with the interface between the layers, as observed by transmission electron microscopy (TEM). The segregated PB enhanced the interfacial adhesive strength. We concluded that the selective distribution of adhesive functional materials along the interface could appropriately retain its adhesive strength.     

Variation of shear modulus through the interfacial bond zone of an adhesive

The variations in shear modulus occurring through the interfacial bond zone (IBZ) of AF 453 adhesive bonded to aluminium have been determined. Acoustic surface (Rayleigh) waves at ultrasonic frequency were propagated along surfaces of the adhesive sequentially exposed from the bulk through the IBZ towards the bondline. The propagation speed of these sound waves over the adhesive surfaces was then used to obtain the shear modulus of the material at each layer. With AF 453 adhering to an aluminium substrate prepared according to an industrial standard surface treatment procedure, a linear variation was found for the shear modulos near the adhesive/ adherend interface, independent of cure time. (Cure temperature was that specified by the manufacturer). The range of the IBZ was larger for a longer than normal period of cure.     

Effect of fiber pretreatment condition on the interfacial strength and mechanical properties of wood fiber/PP composites

The effect of fiber surface pretreatment on the interfacial strength and mechanical properties of wood fiber/polypropylene (WF/PP) composites are investigated. The results demonstrate that fiber surface conditions significantly influence the fiber–matrix interfacial bond, which, in turn, determines the mechanical properties of the composites. The WF/PP composite containing fibers pretreated with an acid–silane aqueous solution exhibits the highest tensile properties among the materials studied. This observation is a direct result of the strong interfacial bond caused by the acid/water condition used in the fiber pretreatment. Evidence from coupling chemistry, rheological and electron microscopic studies support the above conclusion. When SEBS‐g‐MA copolymer is used, a synergistic toughening effect between the wood fiber and the copolymer is observed. The V‐notch Charpy impact strength of the WF/PP/SEBS‐g‐MA composite is substantially higher than that of the WF/PP composite. The synergistic toughening mechanisms are discussed with respect to the interfacial bond strength, fiber‐matrix debonding, and matrix plastic deformation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1000–1010, 2000     

Effect of hot-etching treatment on shear bond strength of zirconia to resin cement

ABSTRACT

The purpose of this study was to evaluate the effect of hot-etching surface treatment on the shear bond strength between zirconia ceramics and resin cement. Ceramic cylinders were divided randomly into 10 groups (n?=?10) according to different surface treatments (blank control; airborne particle abrasion; hot-etching for 10?min; hot-etching for 30?min; hot-etching for 60?min) and whether or not performed thermal cycling fatigue test. Flat enamel surfaces, were prepared from human permanent incisors and were bonded to the zirconia discs. All specimens were subjected to shear bond strength test by a universal testing machine. All data were statistically analysed using one-way analysis of variance and multiple comparison least significant difference tests (α?=?0.05). Hot-etching for 60?min treatment produced higher bond strengths than the other treatment. Surface treatment of zirconia with a hot-etching solution might enhance surface roughness and bond strength between zirconia and resin cement.     

Shear bond strength tests of zirconia veneering ceramics after chipping repair

All ceramic systems are replacing the classical metal–ceramic crowns in dental practice. Zirconium dioxide (zirconia) core associated with veneering ceramic provides both good mechanical and aesthetic properties of prosthetic restorations. However, such zirconia crowns may be affected by defects of adaptation, too tight contacts in the proximal area and fissures of the ceramic veneer. The latter produces chipping; this requires a reattachment, therefore a second burning of the zirconia–ceramic interface. Such an additional procedure may affect the mechanical resistance of the ceramic veneer and the bond between the zirconia core and the ceramic veneer. The aim of this study was to evaluate the alterations of this shear bond strength (SB) between the zirconia core and the ceramic veneer, as produced by the first set of complete burning procedures and by the second correction burning of the dental restorations. Thirty-three zirconia discs were veneered with ceramic material and the SB was evaluated for each sample. Each ceramic cylinder detached from the zirconia was bonded on the core through a new layer of dentin and another burning procedure; the SB was tested again. The results of the two SB tests were compared; the statistical analysis concluded that there is an approximately 10% decrease of the resistance after the second burning. Also, the spread of the values for each test showed the high impact of the human factor on such dental restorations. In all the tests, the weakest area proved to be the interface between the zirconia core and the layered ceramics.     

Peel and shear strength of pressure‐sensitive adhesives prepared from epoxidized natural rubber

Peel and shear strength of two grades of epoxidized natural rubber (ENR 25 and ENR 50)‐based pressure‐sensitive adhesive was studied. Coumarone‐indene resin was used as the tackifier, whereas toluene was chosen as the solvent throughout the experiment. The tackifier loading was varied from 0 to 80 parts per hundred parts of rubber (phr). A SHEEN hand coater was used to coat the adhesive on substrate to give a coating thickness of 30, 60, 90, and 120 μm. Peel strength and shear strength of the adhesive were determined by using a Lloyd adhesion tester and Texture analyzer, respectively. Results show that maximum peel strength occurs at 40 phr of coumarone‐indene resin for both ENRs studied an observation, which is attributed to the maximum wettability of the substrate. However, the shear strength shows a gradual decrease with increasing tackifier loading because of the decrease in cohesive strength of adhesive. ENR 25 consistently indicates higher peel strength and shear strength than ENR 50. Generally, peel and shear strength increases with coating thickness. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007.     

Aging effect in the adhesion of a PC/CPVC arrangement for application in thermo-solar collectors

This work studies the aging of materials in a polycarbonate/chlorinated polyvinyl chloride (PC/CPVC) arrangement, used in a flat plate thermo-solar collector. Typically, PC is used as an absorbing surface and CPVC in entrance and exit heads of the flow, which in this case is water. In this study, two types of methacrylate adhesives were used to bond both plastics, denominated MP and SK. The experiment comprised a study of adhesion behavior between these polymers and the adhesives, in contact with distilled water at different temperatures and different time intervals, simulating the corresponding operating conditions of a thermo-solar collector. Results showed that the SK adhesive did not fail under these conditions, while the MP adhesive underwent evident aging and adhesive failure. In addition, the PC presented a reduction in its mechanical strength when it was subjected to higher temperatures and periods of hygrothermal exposure, probably due to physicochemical deterioration caused by hydrolysis.     

Effect of different application techniques on microshear bond strength of self-etch adhesives to dentin

Objectives: To investigate the effect of different self-etch adhesive systems application techniques: active or passive in a single or double layer on adhesive–dentin microshear bond strength.

Methods: Occlusal surfaces of 48 extracted human molars were ground to expose flat superficial dentin surfaces. Specimens were randomly divided into two main groups according to the tested self-etch adhesive system either: One-step self-etch (Adper^TM easy-one) or two-step self-etch (Adper^TM SE Plus). Each adhesive system was applied on the prepared dentin surfaces followed one of these techniques: (1) Passive application of a single layer, (2) Active application of single layer, (3) Passive application of double adhesive layer (with light curing in between), and (4) Active application of double adhesive layers. Resin composite was packed inside micro-tubes fixed on the bonded dentin surfaces and light cured for 40 s. All specimens were stored in artificial saliva either for 24 h or 3 months before testing. Microshear bond strength test was employed using a universal testing machine at a crosshead speed of 0.5 mm/min.

Results: Adper^TM SE Plus showed higher significant microshear bond strength in compared with Adper^TM easy-one. For both adhesive systems active application showed higher significant microshear bond strength to dentin than passive application. Double application of adhesive systems showed lower microshear bond strength than single application.

Conclusion: Active application of self-etch adhesives could improve the dentin microshear bond strength. Double application with curing in between the layers did not improve the bond strength to the tested adhesive.     

Bond strength and durability of universal adhesive agents with lithium disilicate ceramics: A shear bond strength study

The aim was to assess the shear bond strength (SBS) of lithium disilicate (LD) ceramic to resin composite with different universal adhesives, duration of ageing and silane. One hundred and twenty LD ceramic discs were processed, fired and etched (HF acid 5%) for 20 s (sec). All specimens were divided into 12 groups (n = 10), based on different combinations of, 3 different universal adhesives [Scotchbond (SB) Universal Adhesive, All-Bond (AB) Universal, and Futurabond U (FU)], silane and different duration of ageing [24 h and 3 months]. Composite resin cylinders (Tetric ceram) (3mm × 2 mm) were formed using bonding jig on ceramic and were light-cured. The specimens in groups 1–6 and 7–12 were stored in distilled water (37 °C) for 24 h and 3 months (thermocycling -5000 cycles 5–55 °C/30 s dwell time) before being subjected to bond strength testing respectively. Using universal testing machine shear bond test was performed at a crosshead speed of 1 mm/min. Failure modes and fracture patterns were assessed using stereomicroscope and scanning electron microscope. Analysis of variance was performed to analyze data. SBS was significantly higher with silane than without silane (p < 0.01), regardless of the type of adhesive or storage duration. Specimens tested at 24 h storage showed significantly higher (p < 0.01) SBS than specimens tested after 3-months. A comparison among different universal adhesives showed significantly distinct bond strength (p < 0.01). Optimal bonds to LD were achieved by application of silane. While ageing through storage had a negative impact on the SBS, it varied among different adhesives.     

Efficacy of novel cleansing agent for the decontamination of lithium disilicate ceramics: a shear bond strength study

Purpose: To investigate the efficacy of Ivoclean as a ceramic cleansing agent, by assessing shear bond strength of pre-etched lithium disilicate (LD) ceramic to resin cement.

Materials and Methods: Seventy LD discs (10 × 10 × 4 mm) were fabricated and etched using 5% hydrofluoric acid (HF) for 20 s. Ten specimens were not exposed to saliva and silicone disclosing medium (negative control). The other 60 specimens, divided into six groups (n = 10), were exposed to saliva for 20 s and silicone disclosing medium for 3 min. Following contamination, 10 specimens were not cleansed (positive control). The remaining five groups were exposed to one of the five different cleansing agents: 96% isopropanol, 37% phosphoric acid-30 s, 5% HF acid- 20 s, 5% HF acid- 120 s, and Ivoclean paste-20 s. All specimens were treated with primer and bonded to a self-curing resin cement. Before shear bond strength testing, all specimens were thermocycled (3000 cycles; 5–55°).

Results: Contamination of pre-etched LD ceramic specimens significantly reduced the shear bond strength values from 22.39 ± 0.38 MPa (negative control) to 6.54 ± 0.90 MPa (positive control) (p < 0.05). Cleansing of contaminated ceramic specimens with 5% HF acid [20 s (19.28 ± 1.06 MPa) and 120 s (20.04 ± 1.09 MPa)] and Ivoclean (18.30 ± 0.97) provided significantly higher bond strength values than other cleansing methods with 37% phosphoric acid and 96% isopropanol (p < 0.05).

Conclusion: Ivoclean and 5% HF acid were found to be effective in cleansing of LD ceramic surface by demonstrating maximum increase in shear bond strength values as compared to contaminated LD ceramics.     

Effect of calcium hydroxide removal techniques on the bond strength of root canal sealers

To evaluate the influence of calcium-hydroxide(CH) with different vehicles on the push-out bond strength of different canal sealers to radicular dentin. 152 decrowned single-rooted human teeth were used. After preparation of root canals with nickel-titanium rotary files, 8 roots served as control groups. Then, the roots were divided as follows: (1) Calasept and (2) Surepaste (n = 72). Roots were further subgrouped according to the CH removal techniques: (1) %17 ethylenediaminetetraacetic acid (EDTA) + rotary file, (2) %17EDTA + hand file, and (3) %17EDTA (n = 24). Eight roots from each group sectioned longitudinally, divided into two pairs and photographed by stereomicroscope (n = 16). The remaining 16 roots in CH intracanal dressing groups were further divided into 2 subgroups according to the sealer used: (1) AH-Plus-jet and (2) Apexit-Plus (n = 8). Bond strengths of the root canal sealers to root canal dentin were measured using a push-out test setup. The data were statistically analyzed using multivariate analysis of variance p = 0.05. The push-out bond strength values were significantly affected by type of vehicle and the removal techniques (p < 0.05). The mean bond strength of AH-Plus-jet was significantly higher than Apexit-Plus, regardless of type of vehicle and the removal techniques (p < 0.05). There was no difference between vehicles on CH removal (p > 0.05). When examining the removal techniques, only irrigation with %17 EDTA left significantly larger amount of residue (p < 0.05). AH-Plus-jet showed better dislocation resistance than Apexit-Plus. Type of vehicle does not play a fundamental role in the degree of persistence of CH residues on the dentin walls. Instrumentation improves the removal efficiency of CH from root canal.     

Effect of different surface shapes formed by femtosecond laser on zirconia-resin cement shear bond strength

Objective: The purpose of this study was to evaluate the effect of different surface shapes formed by femtosecond (FS) laser on zirconia (Y-TZP)-resin cement shear bond strength (SBS). Background data: All ceramic restoration is used as an alternative to metal-ceramic restorations, due to its better aesthetics, strength, and toughness properties. However, bond strength of restoration to tooth and other materials is effective to long term success of the restoration, and to achieve it surface treatment is required on ceramic surface. Materials and methods: Forty square-shaped zirconia samples were prepared and assigned to four groups of 10. The details of the groups are as follows: Group A, square-shaped recessed surface; Group B, square-shaped projection surface; Group C, circular-shaped recessed surface; Group D, circular-shaped projection surface. The SBSs values were performed with a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed statistically using analysis of variance (ANOVA) and Tukey HSD multiple comparisons tests. Results: The one-way ANOVA results on SBSs of the zirconia material bonded with resin cement revealed significant differences among the groups (p < 0.05). The Tukey HSD test results revealed that Group B and D had significantly higher SBS values than other groups (p < 0.05), but there were no significant differences between each other (p > 0.05). Additionally, Group A and C had significantly lower values than other groups (p < 0.05). Conclusions: Different surface shapes formed by FS laser provided a significant increase in SBSs. The SBS values of projection surfaces of circular and square-shapes are greater than that of recessed surfaces of circular and square-shapes.     

微脱黏法在碳纤维/环氧树脂界面性能评价中的应用

利用微脱黏法测定碳纤维/环氧树脂复合材料的界面剪切强度,并分析了造成测试结果分散的影响因素.结果表明:在脱黏过程中,最大脱黏力随碳纤维埋人环氧树脂内长度的增加而线性递增,当埋人长度超过一定值后最大脱黏力趋于稳定:碳纤维与环氧树脂间的接触角对复合材料界面剪切强度有一定影响,接触角越大,界面剪切强度越高;测试结果的分散性与树脂微球的半月板区域、钳口区等因素有关;未经表面处理的碳纤维增强环氧树脂复合材料的界面剪切强度仪为39.4 MPa,低于处理后的复合材料(60.6 MPa).     

In vitro degradation behavior of carbon fiber-reinforced PLA composites and influence of interfacial adhesion strength

In the present study, carbon fiber-reinforced polylactide (C/PLA) composites with different interfacial conditions were prepared to determine the influence of interfacial adhesion strength (IAS) on in vitro degradation behavior of the C/PLA composites. Pure PLA and untreated and treated C/PLA composite samples were immersed in phosphate buffered saline (PBS; pH 7.4, 37 ± 0.5^°C) for predetermined time periods. These samples were removed at each degradation time, measured to analyze molecular weight loss, weighed to assess water uptake and mass loss, and mechanically tested to obtain bending strength, modulus, and IAS. The matrixes in the C/PLA composites showed higher water uptake and lower mass loss in comparison with the pure PLA. Further, the PLA matrix in the treated composite absorbed less water and lost less mass and molecular weight than its counterpart in the untreated composite. Mechanical tests confirmed that the treated C/PLA composite exhibited a slower rate of decrease in bending strength, modulus, and IAS than the untreated one. The differences in degradation behavior between two composites can only be attributed to the difference in interfacial conditions because all other parameters were kept constant. The loss of bending strength and modulus was mainly caused by the interface degradation of the C/PLA composites. It can be concluded from our in vitro observations that the IAS had an obvious influence on the degradation characteristics of the C/PLA composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 150–158, 2001     

Influence of surface treatment of carbon fibers on interfacial adhesion strength and mechanical properties of PLA‐based composites

In the present study C/PLA composites with different fiber surface conditions (untreated and with nitric acid oxidation for 4 h and 8 h) were prepared to determine the influence of surface treatment on the interfacial adhesion strength and mechanical properties of the composites. A chemical reaction at the fiber–matrix interfaces was confirmed by XPS studies. Nitric acid treatment was found to improve the amount of oxygen‐containing functional groups (particularly the carboxylic group, —COOH) on carbon fiber surfaces and to increase the surface roughness because of the formation of longitudinal crevices. The treated composites exhibited stronger interface adhesion and better mechanical properties in comparison to their untreated counterparts. There was a greater percentage of improvement in interfacial adhesion strength than in the mechanical properties. The strengthened interfaces and improved mechanical performance have been mainly attributed to the greater extent of the chemical reaction between the PLA matrix and the carbon fibers. The increased surface roughness also has had a slight contribution. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 367–376, 2001     

A microdebonding test for in situ assessment of fibre/matrix bond strength in composite materials

A test technique which gives a quantitative measure of the in situ fibre/matrix bond strength in fibre-reinforced composite materials is described. The test involves the compressive loading of a fibre or region of fibres on a polished specimen surface to produce debonding. Results are presented for the debonding load for glass/epoxy, aramid/epoxy and graphite/epoxy composites. The change in debonding load is also followed as the interface degrades during moisture conditioning at different points through the thickness of the material. It is concluded that refinements to the technique are needed to simplify interpretation of the debonding force in terms of interface shear strength, and to make the test more reproducible.