The Interfacial Bond Strength in Glass Fibre-Polyester Resin Composite Systems

The interfacial bond strength in glass fibre-polyester resin composites has been investigated using various experimental techniques. These included blocks of resin containing fibre (in which, depending on the geometry of the specimen, failure occurs in either a shear or tensile mode) the pullout of a fibre from a disc of resin and a short beam shear test for interlaminar shear strength determination.

Low power optical microscopy and optical retardation measurements of stress induced birefringence were used to detect the difference between intact and debonded fibre resin interfaces. The shear modulus and shear strength of the resin were obtained from torsion tests on cylindrical rods of the resin.

The single fibre shear debonding specimen and the short beam shear test are shown to be the most viable test methods but interpretation of the results is complicated by the various modes of failure possible and by the different stress states which exist in the area of the specimen where debonding starts. Stress concentration factors obtained by finite element analysis and photoelastic analysis have been applied to the results from these tests and the corrected interfacial bond strengths are in close agreement.

The real interfacial bond strengths of well bonded glass-fibre polyester resin systems is shown to be of the order of 70 MN m^?2.     

The Interfacial Bond Strength in Glass Fibre-Polyester Resin Composite Systems Part 2. The Effect of Surface Treatment

The effect of surface treatments on the bond strength in glass fibre-polyester resin composites has been investigated using single fibre interfacial shear strength specimens and the short beam shear test for interlaminar shear strength.

A range of bond strengths was obtained by using, either alone or in combination, the various components of the size formulation which is normally applied to the fibres, so that the interaction between the glass surface and the polyester ranged from Van de Waal forces through hydrogen bonding to covalent bonding, the bond strength increasing in that order.

The relative contribution to bond strength of mechanical bonding due to thermo-mechanical mismatch between the two components and of chemical bonding or physical interaction between the three phases, glass-surface treatment-resin, has been evaluated and found to be one third and two thirds respectively.     

Bond Strength and Interfacial Ultramorphology of Current Adhesive Systems

This study evaluated the bond strength and ultramorphology of the resin-dentin interfaces produced by current dental adhesive systems. Nine dentin bonding agents were investigated. Restored teeth were vertically, serially sectioned to obtain bonded slices for interfacial TEM analysis or to produce bonded beams for the microtensile bond strength test. The one-step self-etching adhesives (Futurabond® NR and Hybrid Bond®) showed lower bond strength values than the three-step etch-&-rinse adhesive system All-Bond 3. Most bonding agents presented statistically similar mean bond strength values, which ranged from 41.3 ± 17.9 to 35.0 ± 5.3 MPa. The thickness of the hybrid layer varied according to the type of adhesive system used. While the etch and rinse adhesives with alcohol as organic solvent showed bond strength means higher than 40 MPa, the self-etching systems showed bond strength lower than 40 MPa. Resin-dentin interdifusion zone and resin tags were noted in all bonded interfaces.     

Interfacial Bond Strength in SiC/C/SiC Composite Materials, As Studied by Single-Fiber Push-Out Tests

The interfacial characteristics of SiC/C/SiC composites with different fiber-coating bond strengths have been investigated using single-fiber push-out tests. Previous studies have shown that weak or strong bonds can be obtained by using as-received or treated fibers, respectively, and that the stress-strain behavior is improved with the treated fibers. This effect results from multiple branching of the cracks within the interphase. The model used to extract interfacial characteristics from nanoindentation and microindentation tests does not consider the presence of an interphase. However, the results highlight the significant effect of the interphase on the interfacial parameters, as well as the effect of roughness along the sliding surfaces. For the composite with treated fibers, the uncommon upward curvature of the push-out curves is related to different modes of crack propagation in the interphase. Different techniques are required to analyze the interfacial properties, such as nanoindentation and microindentation with push-out and push-back tests.     

Evaluation of the Microtensile Bond Strength between Resin Composite and Hydrofluoric Acid Etched Ceramic in Different Storage Media

The aim of this study was to evaluate the effects of storage media on the bond strength between resin composite and ceramic that was etched with hydrofluoric acid and silanized. Two types of ceramics were used: lithium disilicate and leucite-reinforced. The ceramic surface was etched with 4.7% hydrofluoric acid and bonded to the resin composite using a silane coupling agent. Specimens were divided into 10 groups and each group of specimen was subjected to different types of storage conditions for 7 days: de-ionized water (control), 15% ethanol, lemon soda, and cola. The microtensile test was used to measure the bond strength. The results showed that storage in food beverages significantly reduced bond strength compared to controls because of the acidity of beverages (ANOVA; p < 0.05). Lithium disilicate ceramics stored for 7 days in ethanol produced bond strengths significantly lower than those stored in 7 days in de-ionized water (p < 0.05). Leucite-reinforced ceramics stored for 7 days in lemon soda generated mean bond strengths significantly lower than those stored for 7 days in de-ionized water (p < 0.05). The significance of this in vitro study is that patients who have just repaired fractured crowns or inserted laminates should refrain from drinking acidic substances because it may weaken the resin-to-ceramic bond.     

Effects of Self-Etching Adhesive Systems Used in the Dental Modelling Technique on the Cohesive Strength of Composite Resin

This study evaluated the cohesive strength of composite using self-etching adhesive systems (SE) in the lubrication of instruments between layers of composite. The specimens were made by using a Teflon® device. SE were used at the interface to lubricate the instruments: Group 1(G1) – control group, no lubricant was used; Group 2(G2) – Futurabond® M; Group 3(G3) – Optibond® All-In-One; Group 4(G4) – Clearfil® SE Bond; Group 5(G5) – Futurabond® NR; Group 6(G6) – Adper® SE Plus; Group 7(G7) – One Up Bond® F. Specimens were submitted to the tensile test to evaluate the cohesive strength. Data were submitted to the ANOVA and Tukey tests. ANOVA showed a value of p = 0.00. The average means (SD): G2 = 11.33(±3.44) a, G3 = 15.36(±4.06) ab, G4 = 18.9(±4.72) bc, G7 = 19.62(±4.46) bc, G5 = 21.02(±5.09) bc, G6 = 23.39(±4.17) cd, and G1 = 28.49(±2.89) d. All SE decreased the cohesive strength of the composite, except for Adper® SE Plus.     

夜光环氧树脂/玻璃纤维复合材料研究

将夜光剂添加到环氧树脂(EP)中,采用多层复合拉挤成型制得了夜光EP/玻璃纤维复合材料,研究了复合材料的夜光性能、耐水发光性能及力学性能。结果表明,夜光剂的用量在10份左右、表层厚度为0.10 mm时,复合材料具有长余辉、耐水冲洗、黑夜白天交替的发光性能。     

Investigation of Bond Behavior Between Glass Fiber Composite Reinforcements and Concrete

Worldwide there is a need for the renewal of infrastructure because of age, deterioration, misuse, lack of repair, use of improper materials and techniques, and even due to changing needs. The corrosion of steel reinforcing bars is one of the major causes of degradation of concrete structures. Composites are increasingly being considered as a potential replacement for steel rebar, but there exists a critical lack of fundamental data and understanding of their behavior in relationship to traditional civil engineering materials such as concrete. This paper presents a preliminary investigation on the bond and pullout behavior of glass fiber reinforced composite reinforcement in concrete. The pullout behavior of the system was studied using a concentric pullout test and results are compared with theoretical predictions. The study is aimed at the development of a fundamental understanding of bond behavior and materials-configuration interrelationships needed to further the use of composites as reinforcements for application in areas where corrosion and electromagnetic interference make the use of steel reinforcement inefficient.     

Improvement of Interfacial Adhesion of Glass Fiber/Epoxy Composite by Using Plasma Polymerized Glass Fibers

This study intends to produce plasma polymer thin films of γ-glycidoxypropyltrimethoxysilane (γ-GPS) on glass fibers in order to improve interfacial adhesion of glass fiber-reinforced epoxy composites. A low frequency (LF) plasma generator was used for the plasma polymerization of γ-GPS on the surface of glass fibers at different plasma powers and exposure times. X-ray photoelectron spectroscopy (XPS) and SEM analyses of plasma polymerized glass fibers were conducted to obtain some information about surface properties of glass fibers. Interlaminar shear strength (ILSS) values and interfacial shear strength (IFSS) of composites reinforced with plasma polymerized glass fiber were evaluated. The ILSS and IFSS values of non-plasma polymerized glass fiber-reinforced epoxy composite were increased 110 and 53%, respectively, after plasma polymerization of γ-GPS at a plasma power of 60 W for 30 min. The improvement of interfacial adhesion was also confirmed by SEM observations of fractured surface of the composites.     

空心玻璃微球填充环氧树脂模型材料的研制

以三乙醇胺为固化剂,用真空浇铸法制备了空心玻璃微球（HGM）填充双酚A环氧树脂（E-51）模型材料,对其压缩性能和硬度进行了研究。实验结果表明,环氧树脂／HGM的模型材料的压缩性能随着空心玻璃微球用量的提高而下降,并因不同的固化工艺而下降程度不同。SEM照片表明,模型材料的断裂行为与空心玻璃微珠的用量有关,其硬度随着材料环境温度的提高而下降。     

空心玻璃微珠增强聚四氟乙烯复合材料的制备及拉伸强度的研究

研究了空心玻璃微珠增强聚四氟乙烯复合材料的拉伸强度的变化。研究表明：复合材料的拉伸强度与空心玻璃微珠含量、烧结工艺条件和偶联剂的种类有关;用复合偶联剂处理过的玻璃微珠填充树脂,改善了微珠与树脂的相容性及分散性,从而提高了材料的拉伸强度。并对材料的拉伸强度进行了理论预测。     

Evaluation of the Tensile Interface Strength in Brittle-Matrix Composite Systems

Two test methods for determining the tensile (normal) interface bond strength in brittle-matrix composites have been described: one geometry is the cruciform bend specimen, and the other is the embedded fiber specimen. Both specimens have the characteristic that free edge debonding is avoided, so that valid interface strength data can be obtained from the knee in the stress-strain curve. The techniques are applied to a Sigma SiC/7040 glass composite, and a bond strength of ∼5 MPa has been obtained. The method of analysis is described. Normal interface separation has been observed at or very close to the SiC/carbon (primarily graphite) interface of the Sigma fiber and is consistent with the weak orientation of the graphitic layers. Two examples of interface separation are cited in the as-fabricated composite, to show the application and validation of the test results. In one instance, tensile interface separation has been observed next to existing voids, and in the other instance, interface separation has occurred near radial matrix cracks. Analyses show that the debonds are consistent with the low normal strength of the interface.     

嵌段共聚物偶联剂对玻璃纤维增强不饱和聚酯的界面改性作用

采用原子转移自由基聚合(ATRP)方法合成的聚苯乙烯-b-聚丙烯酸丁酯-b-聚γ-甲基丙烯酰氧丙基三甲氧基硅烷(PS-b-PnBA-b-PMPS)嵌段共聚物偶联剂处理玻璃纤维,研究了共聚物偶联剂对玻璃纤维增强不饱和聚酯力学性能的影响.结果表明:嵌段共聚物偶联剂能有效改善复合材料的强度、模量及韧性,适当增大共聚物中聚苯乙烯嵌段的链长,有利于复合材料的弯曲强度和弯曲模量的提高;复合材料的冲击强度则随着PnBA嵌段链长的增长而提高,但过长的PnBA链长会导致弯曲强度及模量的下降.当PnBA聚合度为50时,可获得强度、模量及韧性均较高的复合材料.     

Predicting Bond Strength

Methods are presented for predicting the load carrying capability of a bonded joint using relatively simple laboratory test samples. It is first shown that using an average stress criterion can lead to errors of an order of magnitude in predicted load carrying capability. A fracture mechanics approach is then shown to predict failure load accurately in a joint bonded with either a polyurethane or a relatively brittle epoxy when proper consideration is given to loading mode, temperature, and load rate. The principal contribution of this paper is in extending fracture mechanics theory to regions where classical singular points do not exist. Analyses are combined with test data to deduce an “inherent” flaw size.     

硅藻土填充聚丙烯复合材料界面黏结强度的定量表征研究

运用硅烷偶联剂对3种不同粒径的硅藻土进行表面改性,采用熔融共混法制备了聚丙烯(PP)/硅藻土复合材料,并测试了3种复合材料的拉伸强度。引入了界面相互作用参数B和黏合角θ对复合材料界面黏结状况进行量化表征。结果表明:复合材料的拉伸强度随硅藻土体积分数的提高而降低;3种复合材料的B值在1.12～1.56之间,均小于3,表明在该实验条件下,硅藻土未能增强PP;3种复合材料的θ值在57.91°～73.74°之间,与B值相比可发现,B值较大的复合材料具有相对较小的θ值,说明B值和θ值均能定量表征复合材料界面黏结强度。     

剑麻纤维/玻璃纤维/酚醛树脂复合材料的性能研究

采用剑麻纤维和玻璃纤维与酚醛树脂共混，制备纤维混杂复合材料；测定其弯曲强度、弯曲模量、无缺口冲击强度、电性能以及耐水浸泡性能；借助扫描电子显微镜观察复合材料的形态结构，并进行理论分析。初步探讨了复合材料的界面行为。结果表明，复合材料在力学性能方面出现正的混杂效应，吸水性能大大降低，在电性能方面没有很大影响。     

Shear Bond Strength of Indirect Composites Luted with Three New Self-Adhesive Resin Cements to Dentin

The aim of this study was to evaluate the shear bond strengths of indirect composites (those cured outside the mouth) luted by three different, recently developed, self-adhesive resin cements to dentin. Seventy caries-free mandibular third molar teeth embedded in acrylic resin and with exposed dentin surfaces were used. Teeth were randomly divided into seven groups. The following application protocols were carried out: a) Group 1 (control group)—direct composite resin restoration (Alert) with total-etch adhesive system (Bond 1 primer/adhesive); b) Group 2—indirect composite restoration (Estenia) luted by a resin cement (Cement-It) combined with the same total-etch adhesive; c) Group 3—direct composite resin restoration with self-etch adhesive system (Nano-Bond); d) Group 4—indirect composite restoration luted by the resin cement combined with the same self-etch adhesive; e) Groups 5–7—indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem®, Maxcem®, and Embrace WetBond®, respectively) onto untreated dentin surfaces. Shear bond strengths of the groups were performed with a universal testing device. Results were statistically analysed by student-t and one way ANOVA tests. The fractured surfaces were also examined by SEM. The indirect composite restorations luted with the self-adhesive resin cements (Groups 5–7) showed successful results compared with the other groups (p < 0.05). Group 4 showed the weakest bond strength (p > 0.05). Open dentin tubules were observed on the total-etch adhesive applied surfaces whereas a smear rich layer was found by SEM on the self-etch adhesive applied surfaces. The new universal self-adhesive resins may be considered an alternative for luting the indirect composite restorations onto the untreated dentin surfaces.     

Effect of Microwave Treatment on the Shear Bond Strength of Denture Tooth/Acrylic Resin

This study investigated the effect of microwave treatment on the shear bond strength of the denture tooth to acrylic resin adhesion, when the glossy ridge laps were unmodified, abraded, grooved, or etched by monomer. Eighty specimens (n = 10) were polymerized in a hot bath at 74°C for 9 hours, and deflasked after flask cooling. Specimens were soaked in 150 mL of distilled water and submitted to microwave treatment in a domestic microwave oven calibrated at 650 W for 3 minutes. Control specimens were not microwave treated. The shear bond strength test was performed in an Instron machine with a cross-speed of 1mm/minute. The ultimate fracture load value was transformed into shear bond strength as a function of the bonding area. Collected data were submitted to ANOVA and Tukey's test (α = .05). Treatment by microwave energy significantly decreased (p < .05%) the shear bond strength values in all ridge lap conditions used for the denture tooth/resin adhesion.