The advantages of using light-curing epoxy adhesives in the sealing of microswitch housings and connectors in the automotive industry are demonstrated. These adhesives are easy to process and cure within seconds, enabling two critical requirements to be met, namely fast processing for large volumes and extremely high reliability.

The benefits of light-curing adhesives and mechanisms of curing of these adhesives are outlined and some recent developments in light-curing adhesives are reported. The new products are Delo-Photobond for glass bonding, Delo-Katiobond (UV curing epoxy) for organic light-emitting diodes and a combined light/heat curing black chip encapsulation compound.

An investigation was carried out to determine the relationship between the critical shear stress for the onset of flow instabilities and the work of adhesion at the polymer/die interface for a series of polyolefins (HDPE, LLDPE, propylene random copolymer and PP) on steel, brass and coated steel. Contact angle and surface tension measurements were performed and the adhesive failure mechanism of Hill et al. assessed to determine if it could explain the strong slip detected for low surface energy systems and the occurrence of instabilities for systems with high surface energies. 22 refs.

Urea-formaldehyde resin was blended with glutaraldehyde and cured with two different curing agents and evaluated as an adhesive for plywood. The resin/glutaraldehyde blends were characterised by FTIR spectroscopy and the gel time, shear strength and water resistance of the adhesives and adhesive joints investigated. 18 refs.

Adhesives composed of demethylated kraft lignin (DKL) and polyethylenimine (PEI) were prepared and evaluated as formaldehyde-free adhesives for wood. Lap-shear specimens were fabricated from maple veneer and the effects of preparation time, curing conditions, total solids content of the adhesive, DKL/PEI weight ratio and PEI molec.wt. on the shear strength and water resistance of the lap-shear specimens examined. The mechanism of curing of the adhesives was also investigated and the adhesives characterised by FTIR spectroscopy. 14 refs.

The results are reported of an investigation into the effect of applied loads between 10 and 100g for areas between 3 and 12 sq.cm. on the friction generated by mucoadhesive films on the colonic surface and the dependence of friction on the area of the adhesive films. The adhesive employed is a high molec.wt. crosslinked polyacrylic acid (Carbopol 971P NF). The results obtained show that the adhesive films on the colonic surface appear to generate macroscopic adhesion-controlled and load-independent friction within a range in which friction is usually load-controlled, resulting in high grip and friction manipulation without applying high normal forces. 25 refs.

The effect of surface pretreatment on the adhesion strength and hydrolytic stability of sol-gel-reinforced epoxy/aluminium adhesive joints was investigated using fracture mechanics to investigate adhesion properties and an asymmetric double cantilever beam wedge test to measure the critical energy release rate, subcritical crack growth kinetics and threshold energy release rate. The aluminium substrates were pretreated by polishing, sanding, grit blasting and chemical etching and their surface morphologies characterised by scanning electron microscopy, optical profilometry and spreading kinetics. The locus of failure of the joints was established by X-ray photoelectron spectroscopy and scanning electron microscopy and an attempt was made to correlate energy release rate with the fractal dimension for joints with macrorough substrates. 63 refs.

An investigation was carried out into the relationship between the rheological properties and peel strength of model adhesives based on quasi-monodisperse anionic polybutadienes containing a terpene-phenolic tackifying resin and Vector triblock copolymers blended with Escorez 2203 and/or ECR 185 tackifying resins. The effects of untreated and surface treated substrates on the relationship between rheological properties and adhesion were examined and competition between adhesion and dissipation in the case of poor adhesion discussed. 21 refs.

A report is presented on the possibility of using the wetting behaviour of a suitable single liquid as a probe to evaluate the suitability of a grit-blasted laminate surface for adhesive bonding. Small drops of DMSO having surface tension characteristics similar to the adhesive are shown to correlate very well with adhesive bond performance for grit-blasted composite surfaces contaminated with silicone mould release agents. The relationship between fracture toughness and failure mode with contamination is examined and the interaction between probe fluids and contaminant analysed. 23 refs. (29TH Annual meeting of the Adhesion Society Inc., Jacksonville, Florida, USA, 19th-22nd February 2006)

Various amounts of montmorillonite modified with a novel intercalating agent, dihydroxyethyl dodecyl trimethyl ammonium chloride, were incorporated into a RTV silicone rubber adhesive system and the cohesive, tensile and thermal properties of the filled adhesive system investigated. The effect of incorporating the modified montmorillonite into the silicone rubber was evaluated using a combination of FTIR spectroscopy, wide angle X-ray diffraction and TEM. It was found that the cohesive strength, tensile properties and thermal properties of the adhesive system containing up to 10 ppr of modified montmorillonite improved markedly. A cohesion mechanism was proposed to explain the improved mechanical properties. 34 refs.

The use of acid-base crosslinking interactions between two polymers as a means of producing hot melt acrylate adhesives with improved cohesive strength was investigated. The effectiveness of the crosslinkers in the adhesive compositions was evaluated by determination of peel strength, shear holding power and rheological properties and the hot melt processability assessed from rheological measurements. Monomers employed included isooctyl acrylate, acrylic acid, N,N-dimethylaminoethyl methacrylate. 4 refs. (28TH Annual meeting of the Adhesion Society Inc., Mobile, Alabama, USA, 13th-16th February 2005)

Oxygen plasma pretreatment followed by silane treatment and surface derivatisation with silane coupling agents were employed to improve the adhesion between an epoxy resin adhesive and SiC-coated silicon wafers. Epoxy-coated SiC/Si were immersed in aqueous solutions at various pHs at 60c for various times to evaluate their durability and adhesion of the epoxy bonded SiC-coated Si wafers investigated by visual inspection to identify debonding and by probe tests to determine the critical strain energy release rate. Surfaces were analysed by X-ray photoelectron spectroscopy following surface treatment and after failure of the samples upon durability testing. 26 refs.

Highly branched polybutyl methacrylate was prepared using emulsion polymerisation, and conditions to induce the maximum amount of branching were explored. High reaction temperatures increased the degree of branching but reduced the reaction rate. Mechanisms leading to this surprising finding were discussed. Gel content increased with both reaction temperature and time, with polymers having some 70 percent gel content showing good shear resistance. Polymers were characterised using nuclear magnetic resonance spectroscopy, size exclusion and headspace chromatographies, dynamic light scattering, solvent extraction, solvent swelling, and measurement of adhesive properties under shear and by tack measurement. 30 refs.

The synthesis of macrocyclic arylene thioether ketone oligomers and a linear poly(phenylene sulphide ketone) oligomer, and their characterisation by proton and carbon-13 NMR, MALDI-TOF MS, DSC and FTIR, is described. The effects of the linear oligomer on the uncatalysed ring-opening polymerisation of the macrocycles were investigated under dynamic heating conditions using DSC, and the results are discussed in terms of potential applications in high temperature adhesives and sealants. 22 refs.

The effectiveness of polymer coatings based on blends of ethylene-propylene-diene terpolymer and various proportions of polyethylene as corrosion protection for a carbon steel alloy pipeline in sea water was investigated using electrochemical methods, ICP, SEM and XRD. The effects of blend composition, coating thickness, and the application of an adhesive on the substrate, on the protective properties of the coatings are discussed. 22 refs.

Compared to mechanical fasteners and welding, structural adhesives evenly distribute stress, act as sealants, reduce noise and vibration, help prevent corrosion and maintain the original mill finish of exterior surfaces of thin panels. OEMs that have integrated adhesives into their designs have benefited from immediate return on investment, reduced labour and materials costs, and more-efficient production. In order to switch to an adhesive joint, the designer must embrace the conversion process. This includes understanding the chemistry behind adhesives, outlining a proper implementation plan and partnering with a reputable adhesive supplier. Bonding of metals, thermoplastics and natural materials with acrylic, epoxy and urethane structural adhesives is outlined.

Stepper motors find use in a wide variety of high-precision applications including medical equipment, industrial robots and video cameras. Many of these uses need motors with customer winding patterns, shaft configurations, housings and bearings. Light-curing acrylic adhesives help motor makers balance the demands of small, customised batches and short lead times. In ambient light, all but the fastest light-cure adhesives stay liquid long enough to do multiple part adjustments. Exposing the adhesive to light of a proper intensity and wavelength triggers a photoinitiator that starts the curing process. Approximately 10 to 30 seconds of light exposure cures adhesives to a depth of about 13mm or more.

Silicones prepare buildings and structures to endure natural and man-made disasters. Silicone is intrinsically resistant to heat, wind, moisture and chemicals. Silicone sealants and adhesives stand up to sun, salt, pollution and age better than other products on the market. Silicones bond even the most diverse materials, such as concrete, glass, granite, marble, aluminium, steel and plastics. This translates into silicone's ability to bring strength and enhanced structural performance to building materials. Silicone sealants and adhesives add a protective layer that strengthens and adds water repellency and breathability to natural material. Finally, integrating silicone with building materials provides architects and civil engineers additional design flexibility.

The adhesives and sealants industry relies heavily on valves to control the flow of fluids in the formulation and application of its products. Valves are a critical link in the processing systems used for adhesives and sealants, as are the actuators that control them. New "smart" electronic valve actuators can save significant time and money by increasing safety and efficiency, reducing maintenance costs and improving the quality of the final product. Electronic actuators, such as the Flowserve Limitorque MX, are able to operate under the harshest conditions while maintaining predictable, reliable and safe operation.

Energy-curable pressure-sensitive adhesives can be either hot-melt or room-temperature liquids. RAHN USA has done extensive work studying the tendencies and developing starting point formulations. This article examines the basics of formulating these adhesives with a specific end property in the mind of the formulator. A liquid radiation-curable PSA is comprised of four essential components: elastomer, tackifier, diluent and photoinitiator. The elastomeric in this case is a combination of monofunctional and difunctional aliphatic urethane acrylate oligomers. 3 refs.

For the first time, formulated product (including adhesives, sealants and coatings) producers are developing products with environmentally responsible properties because of the needs of the market, not to meet mandatory governmental regulations. The emergence of specifications and certifications of materials that meet certain environmental criteria is emerging in the building and construction industries of North America and Western Europe. ChemQuest forecasts that this trend will be a factor driving new product development throughout the adhesives and sealants value chain over the next decade. This article provides an overview of the trend, along with guidance on the facets that impact adhesives and sealants producers and users.

The bonding of polymer matrix composites using magnetic particulate susceptor materials for hysteresis induction heating is investigated in this study. Hysteresis heating is tailored through careful design of the microstructure of magnetic particulate polymer films. The bond strength of hysteresis-welded materials is comparable to that of autoclave-welded materials while offering an order of magnitude reduction in cycle time. The relative contribution of the intimate contact and healing mechanisms to fusion bonding process indicates that it is intimate contact controlled. The macroscopic failure modes of hysteresis bonded specimens include adhesive composite/film, cohesive film and cohesive composite. Inspection of the microscopic failure at the nickel particle/polymer interface in the film indicates quasi-brittle failure mode. The XPS peaks confirm nickel oxide in the form of NiO on the failure surface indicating adhesive failure at the particle/polymer interface. The area fraction of adhesive failure is found to increase with decreasing particle size and increasing particle volume fraction. 23 refs.

Organic-inorganic hybrid materials were prepared using the sol-gel process in order to improve the scratch resistance of poly(methyl methacrylate) (PMMA) substrates. Sol-gel solutions based on tetraethoxysilane and alpha,omega-triethoxysilane terminated polycaprolactone with two different organic/inorganic weight ratios (5/5 and 7/3) were applied and cured on the substrate. The final coatings consisted of interconnected nanodomains of silica and polycaprolactone, which increased in size and resulted into microdomains when the content of organic phase increased. The surface energies of coated and uncoated PMMA, and the cohesive and adhesive properties of the hybrid coatings were examined using contact angle measurements, and fragmentation tests, respectively. The surface energy of the hybrid coatings and their work of adhesion to the PMMA substrate were found to be similar, with a higher polar contribution at increasing silica content. In contrast, the strain to failure, cohesive strength, toughness and adhesion to PMMA of the coating with a 5/5 organic/inorganic ratio were considerably higher, compared to the coating with a 7/3 organic/inorganic ratio. These results demonstrate that the adhesion strength is the result of a series of complex phenomena that probably involves diffusion of reactants in PMMA and their crosslinking, as suggested by electron energy loss spectroscopy analyses, other than effects deriving from residual stresses and from the morphology produced during the formation of the coating. 19 refs.

Polymer nanocomposites of core-shell structure were prepared by grafting poly(methyl methacrylate) (PMMA) from TiO"2 nanoparticle via the surface-initiated polymerisation (SIP) strategy. A bifunctional polymerisation initiator inspired by l-3,4-dihydroxyphenylalanine (DOPA), a key constituent of mussel adhesive proteins (MAPs), was designed and synthesised for use in SIP from oxide surfaces. The biomimetic initiator spontaneously adsorbed to TiO"2 from aqueous solution, resulting in a colloidal initiator system with the initiator content of approximately 6.8 wt%. Subsequent in situ activation of the surface-initiated atom transfer radical polymerisation (SI-ATRP) gave rise to PMMA polymer shell layers tethered to TiO"2 nanoparticle cores. The results demonstrate a viable biomimetic strategy toward the preparation of polymer functionalised metal oxide nanoparticles that may be useful for construction of functional polymer nanocomposites. 54 refs. Copyright (c) 2006 Elsevier Ltd.

Poly(bisphenol A acryloxyethyl phosphate) (BPAAEP) being used for UV curable flame retardant coatings and adhesives, was synthesised from phosphorus oxychloride, hydroxylethyl acrylate and bisphenol A as raw materials, and characterized using 1 3C NMR, 3 1P NMR, FTIR, MS and GPC measurements. A series of formulations with different ratios of BPAAEP to urethane acrylate, EB220, were prepared to obtain flame retardant resins. The flame retardancy of the UV cured films was investigated by the limiting oxygen index (LOI). A synergistic effect between phosphorus and nitrogen was observed when 1.5wt% phosphorus was presented in the resin. Their maximum photopolymerisation rates (R"p m a x) and final unsaturation conversion (P f) in the cured films at the presence of a 3wt% photofragmenting initiator were investigated. The results showed that the P f increased with increasing EB220 content photo-DSC analysis. The data from dynamic mechanical thermal analysis showed that BPAAEP has good miscibility with EB220. Moreover, the crosslink density and T"g of the cured film decreased along with the content of BPAAEP in the blend. 39 refs.