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The article presents a list of papers published in the 2004 and 2005 issues of the "Journal of Materials Science." Some of the papers listed are: "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials"; "Role of Entropy of Fusion in Phase Transformation and Self-Diffusion"; "Models in Thermoluminescence"; "Electrical Applications of Carbon Materials"; "Use of Polymers for Cement-Based Structural Materials"; and "Effect of Anions on the Textural and Catalytic Activity of Titania-Silica Mixed Oxide."

A list of articles related to physics is presented in the December 2005 issue of the "Journal of Materials Science" including "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," by A. Baldan, "Thermo-mechanical fatigue of shape memory alloys," by E. Hornbogen, "Role of Entropy of Fusion in Phase Transformation and Self-Diffusion," by G. P. Tiwari, J. M. Juneja and Y. Ijima, "Models in Thermoluminescence," by C. Furetta and G. Kitis and "Electrical Applications of Carbon Material," by D. D. L. Chung.

Continuous roll-to-roll fabrication is essential for transferring the idea of bio-inspired, fibrillar dry adhesives into large-scale, synthetic, high-performance adhesive tapes. Toward this aim, we investigated process parameters that allow us to control the morphology and the resulting adhesion of mushroom-shaped micropatterned surfaces. Flexible silicone templates enabled the replication process of the polyurethane acrylate pre-polymer involving UV-light-induced cross-linking. For this paper, we particularly tailored the polyurethane acrylate pre-polymer by adding chemical components to tune UV curing kinetics and to reduce oxygen inhibition of radicals. We found that higher intensities of the UV light and faster reaction kinetics improved the quality of the microstructures, i.e., a larger cap diameter of the mushroom tips was achieved. The polymer blend U6E4 exhibited the fastest curing kinetics, which resulted in a micromorphology similar to that of the Ni-shim master structures. Best adhesion results were obtained for adhesive tapes made from U6E4 with 116 kPa pull-off stress, 1.4 N cm−1 peel strength and 71 kPa shear strength. In addition, repeated attachment–detachment tests over 100,000 cycles demonstrated strong robustness and reusability. [ABSTRACT FROM AUTHOR]

New interconnect materials are always necessary as a result of evolving packaging technologies and increasing performance and environmental demands on electronic systems. Polymer-based conductive-adhesive materials have become widely used in many electronic packaging interconnect applications. Among all the conductive-adhesive materials, the anisotropic conductive adhesives (ACA) (or anisotropic conductive adhesive films, ACF) have gained popularity as a potential replacement for solder interconnects. The interest in using ACA instead of solder comes partly from the fact that the use of ACA for the direct interconnection of flipped silicon chips to printed circuits (flip chip packaging) offers numerous advantages such as reduced thickness, improved environmental compatibility, lowered assembly process temperature, increased metallization options, reduced cost, and decreased equipment needs. In this review, a summary of our understanding of the electrical, physical, thermal, chemical, environmental, and cost behaviors of ACA in conjunction with various packaging applications is elaborated. First, the formulation and curing kinetics of ACA materials, as well as the conduction mechanisms of ACA joints, are introduced; second, the influencing factors, including the boding process (boding temperature, boding pressure, curing conditions, reflow and misalignment processes, etc), the environmental factors (temperature, humidity, impact load, etc), and the properties of the components (the properties of the ACA, substrates, conductive particles, the bump height, etc), on the reliability of ACA joining technology are presented. Finally, future research areas and remaining issues are pointed out. The purpose is simply to pinpoint the most important papers that have played significant role for the advancement of the ACA bonding technology. [ABSTRACT FROM AUTHOR]

Polyacrylate latexes present good film-forming property, and therefore are used in a wide range of applications including coatings, adhesives, additives for paper, textiles, wood, and leather. However, some drawbacks, such as poor elasticity and low hardness have restricted their applications. This review summarizes recent development of polyacrylate latexes modified by polyurethane, organic fluorine, and inorganic nanoparticles, separately, which most often exhibit superior properties to those of their individual components. For each modification method, a comment is given based on our knowledge and related research experience. At last, some perspectives on the future research and development of modification of polyacrylate latexes are concluded. [ABSTRACT FROM AUTHOR]

Rice husks are amongst the typical agricultural residues, which are easily available in huge amounts. They have been considered as raw material for composites panels’ production. However, the major hindrance in rice husks utilization for composite manufacture lies in the lack of direct interaction with most adhesive binders to form the anticipated interfacial bonds. Rice husks are highly siliceous and have poor resistance to alkaline and acidic conditions. Manufacture of rice husks composites panels having good interface bond is difficult and largely dependent on a proper understanding of the interaction between the husks and the binder. This paper presents and discusses results on the production of composites boards from a mixture of rice husks and wattle ( Acacia mimosa) tannin based resin. The experimental results have shown that the ‘as received rice husks’ when blended with alkali-catalyzed tannin resin do not result in optimum composite panel properties. However, it was found that a slight physical modification of the rice husk particles by hammer-milling resulted in drastic improvements in the interfacial bond strength and stiffness of the composites panels from 0.041 MPa to 0.200 MPa and 1039 MPa to 1527 MPa, respectively. [ABSTRACT FROM AUTHOR]

Epoxy resins are widely used in a variety of application fields, thanks to their good mechanical strength, chemical resistance and adhesion to several substrates. Nowadays, the quite majority of epoxy resins are based on derivatives of bisphenol A (BPA), which poses serious health concerns. This issue is pushing the research towards suitable bio-based alternatives to this product, being furan-based epoxies very promising in this respect. In a previous work, 2,5-bis[(oxiran-2-ylmethoxy)methyl]furan (BOMF) was cured with methyl nadic anhydride (MNA), and successfully used as tinplate coating. Herein, in a view of increasing the sustainability of these epoxy resins, we have replaced MNA with maleic anhydride (MA), which can be derived from vegetable feedstocks, thus obtaining a fully bio-based epoxy resin. This latter has then been used as adhesive for carbon fiber-reinforced thermosetting plastics (CFRP). The curing process of the resin was monitored by differential scanning calorimetry (DSC) and chemo-rheological analysis. The results highlighted the significantly higher reactivity of BOMF towards MA compared to the diglycidyl ether of BPA (DGEBA). The crosslinked samples were characterized in their thermal, mechanical and adhesive properties. In comparison to DGEBA/MA and BOMF/MNA, BOMF/MA showed higher ultimate strain and slightly lower glass transition temperature, tensile modulus and ultimate strength. Interestingly, BOMF/MA displayed outstanding adhesive strength on CFRP joints, outperforming the DGEBA-based counterpart by three times. Indeed, by properly selecting the anhydride curing agent, a highly ductile fully bio-based material was developed for high performance adhesive applications. The overall results demonstrate that the properties of BOMF-based epoxy resins can be tailored to meet technical and safety requirements of downstream applications, representing a sustainable alternative to traditional systems containing DGEBA. [ABSTRACT FROM AUTHOR]

Recently, advanced wearable electronic devices have shown great potentials for diverse applications in motion detection, human–machine interaction, and artificial intelligence. However, it is still a challenge to fabricate electronic materials with excellent adhesion and self-healing capability for the construction of various wearable electronic devices. Herein, we report an agar/graphene conductive organogel with excellent self-healing, adhesion and wearable properties. Among others, the adhesion of the agar/graphene conductive organogel is robust to a variety of substrates. The agar/graphene conductive organogel could also be rapidly self-healed based on hydrogen bonding which is triggered by the mechanical force or the near-infrared light irradiation. Furthermore, the agar/graphene conductive organogel can be utilized as the wearable device to detect the human motion and tiny physiological activities sensitively and reliably. We anticipate that the adhesive, self-healable and wearable agar/graphene conductive organogel may have promising potential in electronic wearable devices. [ABSTRACT FROM AUTHOR]

The methacrylated catechol-chitosan (MCCS) was facile prepared using chitosan (CS) sequential crosslinked with 2,3,4-trihydroxybenzaldehyde (THB) and methacrylic anhydride (MA) in mild conditions and then was induced into adhesive hydrogel by photopolymerization with photoinitiator. Structure and morphology of the MCCS adhesive hydrogel were characterized by FTIR, UV, XRD, 1H NMR, and SEM. Physical properties of the MCCS adhesive hydrogel including swelling, degradation, rheology, and adhesive strength were also investigated. These results show that the MCCS adhesive hydrogel with ideal elasticity and good mechanical properties can be quickly obtained by UV (365 nm) irradiation, endowing the photocrosslinked hydrogel exhibits controllable degradation rate and improved adhesive strength. The ultimate adhesion strength of MCCS hydrogel is up to 62.33 kPa, which is more than twice that of hydrogel prepared by CCS. Additionally, the MCCS hydrogel has good cell compatibility and antibacterial activity. The MCCS hydrogel may be a promising candidate material for the development of medical bioadhesives. [ABSTRACT FROM AUTHOR]

The superhydrophobic surface with a high adhesive state (petal effect) has attracted considerable attention owing to its potential applications in fluid transportation. In this study, the preparation of a superhydrophobic surface with a highly adhesive state on carbon steel is reported. By the combination of electrochemical deposition and double glow plasma surface metallurgy (DGPSM), a hard CrFe alloy coating with a rose petal-like microscale structure is prepared. The water contact angle of CrFe alloy coating can reach 163° after modification with 1H,1H,2H,2H-Perfluorooctyltrichlorosilane (PFTEOS). Moreover, the surface exhibits excellent adhesive property with a petal effect. The linear abrasion test demonstrates that the superhydrophobic coating can resist 18 m abrasion distance under a 5 kPa pressure. In addition, electrochemical tests show that the superhydrophobic coating can prevent corrosion from carbon steel effectively. This study provides an effective method to prepare a robust superhydrophobic surface with a high adhesive state for potential industrial applications. [ABSTRACT FROM AUTHOR]

Epoxy resins (ERs) are one of the main types of resins used as structural adhesives; however, they present some weakness, which are mostly related to their highly cross-linked network after the curing process. Low electrical and thermal conductivity and low fracture toughness are the major drawbacks of these type of materials, and several efforts have been made over the past few years to overcome them. A critical survey regarding the use of different fillers in ERs systems and the outcome is highlighted and discussed in the present review. The incorporation of fillers into ERs matrix is one of the most successfully explored alternatives to improve the properties of ERs. It is worth to mention that even though ER composites are a widely explored topic, few reports have been focused on a compilation of the most relevant fillers and the main changes on ERs composites performance. Therefore, the present review gives an overview of a vast selection of fillers—natural, metallic, carbon fillers—incorporated in ER matrices to enhance or to meet the requirements for a desired application, such as the increase in the final adhesive toughness. The combination of the top characteristics of fillers and polymers is accomplished, leading to high-performance composites. Among the most promising fillers, carbon nanomaterials, fiber-reinforced polymers, carbon fiber-reinforced polymers, biofillers and metallic and ceramic fillers are described which have the ones having higher application potential. The influence of the addition of these different types of fillers in ERs system properties such as flame retardancy, mechanical and thermal and electrical performance is discussed and reviewed in detail. [ABSTRACT FROM AUTHOR]

In principle, the conductivity mechanism of electrically conductive adhesives (ECAs) is described by percolation theory. However, no universal conclusion has been reached regarding this matter because these adhesives vary depending on the materials present between metal particles and the intimacy of metal-to-metal contact. In this work, the change in electrical resistivity during curing of silver particle-dispersed epoxy resin adhesives, which are commonly used as ECAs, was measured in situ to evaluate the effect of each component material of the adhesives on its electrical properties. The ECAs containing silver particles coated with different fatty acids exhibited different electrical resistivity changes during curing. Before curing, most of ECAs were not electrically conductive. The ECAs containing silver particles coated with hexanoic acid demonstrated an electrical resistivity of 4.0 × 10–3 Ωm before curing, exhibited a rapid decrease in electrical resistivity at low temperatures (100–140 °C), and achieved an electrical resistivity of 5.5 × 10–7 Ωm after curing. In addition, dipropylene glycol monomethyl ether acetate, the solvent contained in the conductive adhesive, reduced the contact resistance between silver particles. A high amount of the solvent in the ECAs resulted in a low electrical resistivity after curing. Furthermore, in this curing system, cure shrinkage was a minor factor affecting the electrical conductivity. Our study revealed that the thin fatty acid layer provided insulating properties to the silver surface. During curing, the fatty acids were removed from the particle surface via evaporation, and the electrical resistivity of the conductive adhesives decreased considerably. [ABSTRACT FROM AUTHOR]

Inspired by mussel chemistry, adhesive hydrogels represented by polydopamine (PDA) have been widely studied in many fields such as biomedical applications and bioelectronics. However, the process of producing PDA from dopamine often requires specific conditions, which oxidize some of the effective groups and reduce the adhesion effect. So it is important to develop a simple and effective method for fabrication and application of adhesive hydrogels. In this work, an adhesive hydrogel composed of xylan, polyacrylic acid (PAA) and tannic acid (TA) was developed using a facile approach, which exhibited excellent mechanical and adhesion properties. The xylan and TA both from plants could endow the hydrogels with unique properties such as biocompatibility and biodegradability. Surprisingly, the resultant hydrogels exhibited excellent stretchability (extension ratio up to 4600%) and adhesive strength (up to 25 kPa). Besides, the synthesized hydrogels displayed excellent antioxidant and antibacterial properties, while the scavenging rate of 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) radical reached to 94.12%. This study provides a new insight for the design of hydrogels with stretchable, adhesive, antioxidant and antibacterial abilities. [ABSTRACT FROM AUTHOR]

A robust optical strain sensor, called fiber Bragg grating, is employed to measure the effective cure shrinkage—a part of cure shrinkage that is accumulated only after the gel point—of a dual cure adhesive during each stage of curing—(1) UV-curing stage and (2) thermal-curing stage. Unique experimental setups and procedures are developed and implemented to cope with the technical challenges associated with each stage of curing, including gel point detection and uniform curing. The effective cure shrinkage is measured to be 2.1% and 0.78% for acrylate compound (UV-curing) and two epoxy compounds (thermal-curing), respectively. The measurement accuracy of the proposed approach is corroborated by an additional measurement under the identical curing conditions. The results can be used to predict the cure-induced residual stresses of dual curable adhesives. [ABSTRACT FROM AUTHOR]

When it comes to bonding in an aqueous environment, intertidal marine organisms such as mussels, sandcastle worms, barnacles and polychaetes are providing inspiration for the assembly of synthetic molecules into the polymeric adhesives. Although intense demands in various life or industrial applications and many mussel-inspired systems have been shown to develop coatings and hydrogels, exploring the mimetic mussel adhesive system through the control of composition and polymer molecular weight is demonstrated less often. In this report, we showed a simple approach to synthesize mussel-inspired adhesive, P(N-butyl acrylate-co-l-Dopa-methacrylate anhydride), which possesses characteristics of simple synthesis, easy-using, no extra-crosslinker need, and excellent adhesion behaviour on diverse substrates. Adhesion behaviour was examined using low- and high-surface-energy substrates (e.g. PTFE and steel, respectively). Furthermore, the fabricated adhesives exhibited excellent underwater adhesive behaviour for steel in various aqueous solutions, including ion ((IO4)− and Mn3+), acid and alkali solutions (pH = 4, 6.7 and 8, respectively). The outstanding fabricated adhesives take advantage of the catechol functionality and wettability of the resulting polymer. These insights should help us to design next-generation underwater adhesive systems as well as open up a number of future research designs for mussel-inspired adhesives with performance not accessed previously. [ABSTRACT FROM AUTHOR]

To accelerate development of new and improved wood adhesives for engineered wood products, the optimal adhesive penetration into wood needs to be better understood for specific products and applications. Adhesive penetration includes both flow of adhesives into wood micron-scale voids and infiltration into the polymer components of the wood cell wall layers. In this work, X-ray computed tomography (XCT) and X-ray fluorescence microscopy (XFM) were used to study adhesive flow and infiltration. Model wood-adhesive bondlines were made using loblolly pine (Pinus taeda) latewood substrates and bromine-substituted phenol formaldehyde (BrPF) resins with different weight-average molecular weights (MW). The Br substitution facilitated both qualitative and quantitative observations using XCT and XFM. The BrPF resin flow into wood was visualized using XCT volume reconstructions and quantified by calculating the weighted penetration (WP). Examination of the shape of the cured BrPF-air interface in longitudinal tracheid lumina revealed that capillary action often played a role in BrPF flow. XFM mapping revealed the pathways of BrPF infiltration into the wood cell walls, and the results were used to calculate BrPF cell wall weight percent gain (WPGCW) in individual wood cell walls. Both WP and WPGCW decreased with increasing BrPF MW. Additionally, the middle lamella had higher WPGCW than its neighboring secondary cell walls, and within a given bondline the WPGCW decreased with increasing distance of the cell from the bondline. The results provide new insights that are needed in the development of improved models to understand and predict wood-adhesive bondline performance. [ABSTRACT FROM AUTHOR]

Epoxy adhesive as an engineering material has more and more applications in industry. But to date, water resistance of the adhesive is still a very difficult problem to be solved. By mimicking mussel adhesive proteins, dopamine (DA) was applied as one of the two curing agents of epoxy adhesive to improve the water resistance of the adhesive, and the other was phenethylamine (PEA). The effects of the contents of DA on both adhesion property and water absorption of epoxy/PEA/DA adhesives were investigated in detail. The results of lap shear test (LST) showed that the adhesion strength of the epoxy adhesives after the introduction of proper amount of DA was still up to 7 MPa even after the sample was immersed in water for over 230 days. And then the effects of metal ions Zn(II) and Fe(III) on the adhesion properties of the epoxy adhesives were also further studied. It was found that the adhesion strength of the adhesives, when the content of DA was no more than 5 wt%, can be further increased through the complexation of a small quantity of ferric ions with DA. The coordination mechanism of catechol with Fe(III) ions in the system has been investigated by both UV/Vis spectra and XRD curves. The results testified that more bis-catecholate complexes form at high DA: Fe ratios and thus the adhesives have higher cohesion strength for having more regular structures after curing. In a word, the introductions of proper amount of DA and metal ion endow the epoxy adhesive better water resistance and excellent adhesion properties. [ABSTRACT FROM AUTHOR]

A phenol formaldehyde (PF) adhesive was uniformly tagged with iodine such that it yielded sufficient X-ray computed tomography (XCT) gray-scale contrast for material segmentation in reconstructed wood-composite bondlines. Typically, untagged adhesives are organic and have a similar solid-state density as wood cell-walls, and therefore cannot be segmented quantitatively in XCT data. The iodinated PF development involved analysis and comparison of three trial adhesives containing rubidium, bromine, or iodine. Adhesive tag efficacy was measured in terms of X-ray absorption contrast enhancement and tag uniformity along the adhesive polymers. Cured adhesive density, tag element, and concentration were each found to significantly impact XCT contrast results, which in turn agreed with theoretical X-ray attenuation predictions for each resin. Ion chromatography confirmed the absence of free iodide in the liquid PF prior to bonding, and fluorescence microscopy and energy-dispersive spectroscopy (EDS) showed that iodine tags remained associated with the cured adhesive polymers. XCT and EDS results also demonstrated that when contrast agents are simply mixed into resins, rather than attached to the polymer chains, they are free to migrate independent of the penetrating adhesives during bonding. This then can cause complications with quantitative segmentation and analyses. The iodinated PF yielded consistent and uniform XCT gray-scale contrast; its formulation could be adjusted for other viscosity or molecular weight distribution, which would affect its penetration behavior. [ABSTRACT FROM AUTHOR]

Single fiber tensile tests using two different gripping methods were carried out on various fiber lengths. One method (the glue-tab grip method) consists of mounting a fiber onto a rigid tab as specified in ASTM C1557-03 using an adhesive, while the other (the direct grip method) involves directly clamping a fiber using poly(methyl methacrylate) blocks. The tensile moduli obtained by the glue-tab grip as a function of the fiber gauge length are clearly different from those of the direct grip for fiber length between 2 and 10 mm, based on graphical statistical analyses using kernel density and q-q plots. This difference is caused by the gripping effect. In addition, the tensile strains and strengths obtained by the glue-tab grip were different from those of the direct grip at the short fiber gauge lengths (i.e., 2-10 mm). The differences between the tensile properties (i.e., modulus, strain, and strength) for the two grips measured with the 60-mm fiber length were not statistically significant compared to the results with the short fiber lengths. [ABSTRACT FROM AUTHOR]

Pressure-sensitive adhesives (PSAs), which prevent an optical film being shrank under high temperature and high humidity conditions thus protecting light-leakage phenomenon resulting from the stress induced, were synthesized in this study. Such phenomenon occurs in the edge of an LCD panel because the stress is concentrated on its edge and distorts the absorbance axis of a polarizer. To enhance performance of the PSAs, spherical PMMA microbeads were synthesized and added into the acrylic-based polymeric PSAs in this study and then light-leakage properties of each PSAs with spherical microbeads were evaluated by the light-leakage pictures of the samples. Dynamic storage modulus (G′) of the samples was also measured by a rotational rheometer and then correlated with light-leakage characteristics. [ABSTRACT FROM AUTHOR]

Silver nanoparticles are considered to apply a silver paste for electrode because of their high conductivity. However, the dispersion of silver nanoparticles in electronically conductive adhesives (ECAs) restricts them used as conductive fillers. A simple method had enabled the synthesis of silver nanoparticles by reducing silver nitrate with ethanol in the presence of poly( N-vinylpyrrolidone) (PVP). Reaction conditions, such as silver nitrate concentration, PVP concentration, reaction time, and reaction temperature, had been studied. Fine dispersion and narrow size distribution of silver nanoparticles were obtained. They were added to ECAs by re-dispersing them in ethanol while it was used as the diluent to adjust the volatility of ECAs, preventing them from the aggregation and increasing the chance to fill the gaps between silver flakes. This proposed process offers the possibility to effectively use these synthesized silver nanoparticles for improving the conductivity of ECAs. [ABSTRACT FROM AUTHOR]

In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are a bioactive and biodegradable grafting material in the form of a powder and a liquid. Both phases after mixing form a viscous paste that after being implanted sets and hardens within the body as either a non-stoichiometric calcium deficient hydroxyapatite (CDHA) or brushite, sometimes blended with unreacted particles and other phases. As both CDHA and brushite are remarkably biocompartible and bioresorbable (therefore, in vivo they can be replaced with a newly forming bone), calcium orthophosphate cements represent a good correction technique of non-weight-bearing bone fractures or defects and appear to be very promising materials for bone grafting applications. Besides, these cements possess an excellent osteoconductivity, molding capabilities, and easy manipulation. Nearly perfect adaptation to the tissue surfaces in bone defects and a gradual bioresorption followed by new bone formation are additional distinctive advantages of calcium orthophosphate cements. Besides, reinforced formulations are available; those are described as calcium orthophosphate composites. The discovery of self-setting cements has opened up a new era in the medical application of calcium orthophosphates; several commercial formulations have already been introduced as a result. Many more compositions are in experimental stages. In this review, an insight into calcium orthophosphate cements, as excellent biomaterials suitable for both dental and bone grafting application, has been provided. [ABSTRACT FROM AUTHOR]

The effect of pressure on the friction and wear properties of carbon nanotube–silver–graphite composite with 10 A/cm2 and without electrical current has been investigated. The results show that the wear of composite increase with the increase of pressure under mechanical wear, but the wear of composite varies with the pressure in the shape of U under electrical wear. Pressure is a factor related to both the electrical heating, friction heating and abrasive wear. At a reasonable load without much increase in the frictional heating and mechanical wear, the electrical heating could be reduced which will result in lower total thermal effect, and the resultant wear rate could arrive at a minimum. The electrical wear is higher than mechanical wear by 6–20 times. The differences between the no-current and with-current wear is Joule heat released in the friction zone which leads to breakdown of the lubricating film, roughening of the brush surface, and intensification of the adhesive interaction at the contact spots. The wear of positive brush is higher than that of negative brush. The friction coefficient of composite with current is greater than that without current. [ABSTRACT FROM AUTHOR]

Reports on the role of cohesive strength, adhesive strength and oxide thickness in the adherence of porcelain veneered on pure titanium. Use of titanium and its alloys for metal porcelain restorations; Increase of thickness with decrease of bonding strength; Speculation on the degradation of oxide adherence.

Electrically conductive interfaces between metal surfaces, including aluminum, are commonly formed by means of bonding with an electrically conductive adhesive. Humid environments induce an increase in electrical resistance between aluminum objects bonded in this manner. However, joints that are electrically stable through stress testing in environments of elevated temperature and humidity (85°C and 80% RH for up to 137.5 h) have been obtained by treating the aluminum surface with a thin layer (less than 50 Å) of an organo-silane coupling agent, that is, a material capable of bonding chemically with the aluminum oxide surface layer and potentially bonding with the polymer binder in the adhesive. The present study shows that besides their traditional use as surface modifiers for adhesion improvement, organo-silanes can act as corrosion inhibitors of aluminum surfaces to stabilize electrical performance. Whereas other treatments used for preparation of metal surfaces for bonding, using electrically-insulating structural adhesives, typically do not ensure reliable electrical performance, minimal and reproducible increase in resistance has been observed for joints prepared using the procedure described here. Application of this method does not require any significant investment in equipment and the surface pretreatment of the metal surface is quite simple. [ABSTRACT FROM AUTHOR]

A fracture mechanics approach has been used to investigate how the addition of high-temperature resistant thermoplastic modifiers can increase the fracture energy, Gc, of brittle cyanate-ester polymers. Tests were performed using adhesive joint specimens at -55, 21 and 150°C. The fracture energies of poly(ether sulfone)- and polyester-modified cyanate-ester polymers have been measured and scanning electron microscopy has been used to identify the toughening mechanisms involved. Firstly, it is shown that the addition of 25% by weight of a functionalised poly(ether sulfone) (PES) can increase the fracture energy of the cyanate-ester polymers by more than 800%, with the development of a particulate morphology within the modified polymer. Secondly, it is demonstrated that the use of 20% by weight of a polyester-copolymer elastomer can lead to an increase in the fracture energy of up to ten times that of the unmodified cyanate-ester polymer value. Thirdly, it is shown that several of the chemically-modified polymers developed and tested in the present work have fracture energies which are greater than a typical commercially-available cyanate-ester film adhesive. Finally, the effects of long-term ageing in air at 150°C, for up to 7500 hours, on the properties of unmodified, physically- and chemically-modified cyanate-ester polymers are investigated. It is shown that the measured fracture energies of some of these modified cyanate-ester polymers show no significant effect of such long-term ageing. [ABSTRACT FROM AUTHOR]

Blends of high-density polyethylene (HDPE) and isotactic polypropylene (iPP) are used to increase the strength of adhesive bonds between the immiscible polymers HDPE and iPP. Melt blended as well as solution blended material is examined for its suitability to compatibilize the interface between the bonded members. Two standard test methods, the T-peel test and the tensile test, are applied to determine the strengths of adhesive joints. Laminated samples for the peel-tests as well as specimens subjected to the tensile tests were prepared at a temperature exceeding the melting temperature of both homopolymers. TEM and LVSEM examinations were performed for characterizing the morphology of the interface with the aim to determine the parameters which significantly influence the blends' adhesive properties. The bonding strengths obtained with the blended material are discussed with respect to the morphologies of the interfaces, the degree of dispersion in the blend, and the bonding mechanisms. [ABSTRACT FROM AUTHOR]

Most of adhesively bonded joints are under complicatedly distributed triaxial stress in the adhesive layer. For the estimating of the strength of adhesively bonded joints, it is crucial to clarify behavior of yield and failure of the adhesives layer under triaxial stress conditions. Two types of the adhesively bonded joints were used in this study: One is the scarf joint which is under considerably uniform normal and shear stresses in the adhesive layer, where their combination ratio can be varied with scarf angle. The other is the butt joint with thin wall tube in which considerably uniform pure shear can be realized in the adhesive layer under torsional load conditions. These joints can cover the stress triaxiality in adhesive layers of most joints in industrial application. The effect of stress triaxiality on the yield and fracture stresses in the adhesive layer were investigated using the joints bonded by three kinds of adhesives in heterogeneous and homogeneous systems. The results showed that both the yield and failure criterion depend on the stress triaxiality and that the fracture mechanism of the homogeneous adhesive is different from that of the heterogeneous one. From these experimental results, a method of estimating the yield and failure stresses was proposed in terms of a stress triaxiality parameter. [ABSTRACT FROM AUTHOR]