The following is a list of the abstracts for papers which will be presented in THE SEVENTH INTERNATIONAL SYMPOSIUM ON SILANES AND OTHER COUPLING AGENTS. The listing is alphabetical by presenting author. This list is updated continually to add abstracts as they become available and to make appropriate corrections. This list may be conveniently searched by using the editor provided with most popular browsers (e.g. Microsoft Explorer, FIREFOX, Netscape, ... etc.)

Barry Arkles1 , Youlin Pan1 and Eric Eisenbraun2

1) Gelest, Inc., 11 East Steel Road, Morrisville, PA 19067

2) Albany Nanotech

Chemical Bonding to Metals: Hydridosilanes as Coupling Agents

(Abstract not yet available)

Philipp Bringmann1, Franz Gammel1 and Irene Jansen2

1) EADS Innovation Works, Munich, GERMANY

2) Fraunhofer IWS, Dresden, GERMANY

Comparison of Atmospheric Plasma and Wet-chemical Derived Coupling Films as Pretreatment for Structural Bonding

Aqueous solutions of silane coupling agents have been investigated as pretreatments for adhesive bonding of aerospace alloys for many years. More recently, the deposition of silicon-organic precursors in atmospheric pressure plasma jet sources was developed. Within this work, different coupling layers derived from this dry technique are compared to ones made from aqueous silane solutions and by sol-gel technique. Two different plasma jet sources, one based on a dielectric barrier discharge and one based on a controlled arc discharge, are employed for the deposition of precursors like HMDSO and TEOS. Aqueous -GPS solutions and the commercialized AC-130 sol-gel system are used as wet-chemical treatments. The derived films are characterized by SEM, XPS and TOF-SIMS. The adhesion performance of bonded joints is evaluated by floating roller peel (dry and wet) and wedge tests. Additionally, durability of aluminum joints after several pretreatments is determined by bondline corrosion investigations.

The results are quite promising as peel strengths in the range of anodized samples are achieved with both dry and wet pretreatments. However, in terms of bondline corrosion, the stability of the interface after the plasma and silane deposition cannot match the anodizing processes. Nevertheless, significant differences between wet silane and dry plasma treatment can be seen.

Claudius D'Silva and Catalin Fotea; School of Biology, Chemistry & Health Sciences, Manchester Metropolitan University, John Dalton Building, Chester Street, Manchester M1 5GD. UK

e.mail: C.DSilva@mmu.ac.uk

Adhesion Enhancement via the Use of Silane Reagents

Silanes have widely been used in a variety of applications relating to adhesion, such as coupling agents for the attachment of molecules & bio-molecules to sensor surfaces, surface modification reactions to enhance photocatalytic, hydrophobicity or wetting properties and in the self-assembly of molecular and biomolecular arrays .

The porosity of surfaces such as leather and the chemical inertness of glass present major problems to the preparation of adhesive bonds, due to adhesive migration and low reactivity, respectively. In this presentation I will describe the use of silane polymer networks to tackle adhesion problems on leather surfaces and photosilane, photopolymer mixtures that act both as a resist and encapsulant to address adhesion problems on glass surfaces.

M. Tiwari1, W. K. Dierkes1, R. N. Datta1, A. G. Talma1, J. W. M. Noordermeer1 and Wim J. Van Ooij2

1) Department of Elastomer Technology and Engineering, University of Twente, 7500 AE Enschede, THE NETHERLANDS

2) Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221-0012, USA

Tailoring Silica Surface Properties by Plasma Polymerization for Elastomer Applications

The filler surface chemistry is a crucial factor for the dispersion and filler-polymer interaction, thus determining the composite properties. Plasma polymerization is a technique which allows tailoring the surface properties without significantly influencing the structure of the filler material. Acetylene, thiophene and pyrrole were used as monomers for plasma-coating of silica, and the surface-treated silica's were blended with SBR to study their dispersion and reinforcing effect. As reference, untreated and silanized silica were used.

All three monomers resulted in a plasma-coating of the silica surface: a polymeric film with reduced polarity compared to the original silica surface was deposited on the filler surface. When the three plasma-treated fillers were blended with SBR, the filler-filler interaction was reduced compared to untreated silica: polyacetylene had the strongest effect, followed by polythiophene. The filler-polymer interaction was strongest for thiophene treated silica and weakest for the pyrrole treated filler. Dispersion was best after a coating with polyacetylene. Moduli and tensile strength were highest for the thiophene treated filler in SBR, and acetylene treatment had the least effect. Overall, thiophene treated silica performed best in SBR due to a better match with the polarity of the polymer and due to the sulfur moieties on the filler surface allowing network formation.

D. P. Dowling, C. Nwankire and M. Ardhaoui; School of Electrical, Electronic and Mechanical Engineering, UCD, Belfield, Dublin 4, IRELAND

Influence of Precursor Chemistry on the Adhesion of Atmospheric Plasma Deposited Siloxane Coatings onto Stainless Steel

For many decades use of silane coupling agents have dominated as the approach of choice to significantly enhance adhesion between inorganic materials and a wide variety of resins, thermoplastics and elastomers. Recently atmospheric plasma's have been successfully demonstrated as a means of treating metal and polymer surfaces in order to enhance adhesion. In this paper the use of atmospheric plasmas combined with the liquid deposition of precursors will be presented as a technique for the deposition of nm thick functional coatings onto stainless steel. Two approaches were used the first involving the application of a primer layer to enhance the adhesion of siloxane elastomer's to the steel. The second involves the deposition of hydrophobic fluorosiloxane coatings onto the steel.

The primer layers used to enhance the adhesion of the elastomer were deposited from a mixture of polyhydrogenmethyl siloxane (PHMS) and tetraethoxysilane (TEOS). These precursors were mixed at different ratios, and nebulised into a helium plasma formed using an atmospheric plasma jet system. The adhesion of the siloxane elastomer was assessed using 45 peel strength measurements. Results show that the alkoxysilane TEOS plays a major role in improving the adhesion of the primer layer to stainless steel. A 15 fold increase in the adhesive fracture energy of the siloxane elastomer bonded to the plasma polymerized surface was observed. FTIR spectroscopy examination demonstrated that the functional chemistry of the plasma polymerised PHMS has a very significant effect on the adhesion of the siloxane elastomer. In particular it was observed that there was a direct correlation between Si-H peak intensity in the primer layer and the adhesion of the siloxane elastomer.

A second investigation involving the use of the plasma jet system to deposit a fluorinated siloxane coating onto the stainless steel. The coating was deposited using a precursor mixture consisting of trimethyl terminated trifluoropropylmethylpolysiloxane (TFPMS) and TEOS. The performance of the nm thick film onto the steel was assessed using mechanical abrasion tests involving an aqueous based slurry containing aluminium oxide and silicon nitride particles. Coating performance was found to be influenced by the precursor ratio used to deposit the coatings. The tests demonstrated that a ratio of 9 TFPMS to 1 TEOS exhibited the highest abrasion resistance after 5 hour testing. Both these studies demonstrated the important role of the TEOS precursor for both enhancing the adhesion of the nm thick coatings onto the stainless steel as well as improving their mechanical performance.

Lars Kloeser, Carsten Mai and Holger Militz; University of Goettingen

Burckhardt Institute, Woodbiology & Woodproducts, Buesgenweg 4

37077 Goettingen, GERMANY

Use of Waterborn Silanes for Panel Board Applications

Wood particles were treated with waterborne organofunctional silane solutions using 1%, 3% and 5% dry mass of silane related to dry wood mass. The silane solution was sprayed on the particles in a rotating gluing drum. Curing was subsequently performed in a steam dryer at 120C for 5 h. One-layer panel boards were manufactured of untreated and of the silane-treated particles by using a conventional phenoplastic adhesive. The composites exhibited 15mm thickness, adhesive level of 8.5% and a target density of 680 kg/m. After gluing, hand formed particleboards were pressed at 220C for 12 s/mm. Compared to not pre-treated panels, the silane treated boards displayed clear reduction in water uptake and in thickness swelling after 24 h and 72 h water immersion.

Silane treatment also imparted improved mechanical properties. Internal bond strength under dry conditions and especially after 2 h immersion in boiling water was significantly increased.

It is assumed that enhanced dimensional stabilisation and mechanical properties are due to coupling properties of the organofunctional silane at the interface between the particle surface and adhesive. Improved water related properties are crucial for the application of particle boards under outside weathering conditions.

Renee Goreham and Janis Matisons; Nanomaterials group, Flinders University, SOUTH AUSTRALIA

Email: janis.matisons@flinders.edu.au

Kinetics and Properties of New Silane Based Anti-Corrosion Coatings

Silanes are a group of inorganic-organic compounds which are extensively used as adhesion promoters or coupling agents between inorganic and organic materials. Bis-silanes have been primarily used as adhesion promoters or coupling agents in glass reinforced polymer composites for many years. Silanes have recently become of more interest due to their ability to inhibit corrosion of metal surfaces. Silane-based anti-corrosion coatings have become promising replacements for chromate based coatings and silanes have been extensively researched due to their surface affinity and hydrophobic nature. Research by van Ooij has proven that the use of silanes on metals such as galvanised steel and Aluminium alloy provides sufficient (and in some, cases superior) anti-corrosion properties in comparison to chromates.

A silane-based anti-corrosion coating is typically formed on a surface via three steps: (i) hydrolysis; (ii) condensation, and (iii) curing. Hydrolysis is a kinetically favourable reaction for silanes at low and high pH and hence occurs readily in water and protic solvents, such as ethanol. Condensation is a much slower process than hydrolysis, but is influenced by the same parameters (ie: pH, solvent and chemical structure and concentration of the silane). The condensation rate is at a minimum at around pH 4.3 and the reaction is catalysed in the presence of OH-. The curing of the silane on the substrate involves the formation of covalent bonds between molecules and the metal substrate with the loss of water. The extent of crosslinking determines the morphology of the structure, which is important to provide the required anti-corrosion characteristics. We have looked at simpler ways of monitoring the kinetics of hydrolysis and condensation of various silanes, and will report on this, together with the anti-corrosion performance of some of our newly synthesized silanes.

Mutlu Özcan; University of Groningen, Department of Dentistry and Dental Hygiene Clinical Dental Biomaterials, Antonius Deusinglaan 1, 9713 AV Groningen, THE NETHERLANDS

Surface Conditioning Concepts in Adhesive Dentistry: from Theory to Practice

(Abstract not yet available)

Anthony A. Parker1, Calen Bruce2 and David Mariasy2

1) A. A. Parker Consulting & Product Development, Newtown, PA

2) CALEN BRUCE and DAVID MARIASY, Team Audio, Inc., Toledo, OH

Improving Musical Instrument String Longevity with Organosilanes

Organosilane surface treatments have been used to substantially improve the corrosion resistance and longevity of phosphor bronze wound musical instruments strings. Dynamic mechanical analysis (DMA) of surface treated strings reveals that the optimal treatment process leads to a tough film with excellent mechanical integrity and thermal stability. These results will be discussed together with audio-spectral and FTIR analyses of both surface treated and non-treated strings.

J. L. Thomason; Department of Mechanical Engineering, University of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ

A Novel Physical Approach to Interface Strength in Natural Fibre Reinforced Composites

In the past decade there has been an upsurge in the research and development of natural fibres (NF) as reinforcements for composite materials. One of the common justifications for this activity is that the some properties of some of these fibres can match, and therefore potentially replace, glass fibres which currently account for >95% of the reinforcement fibres used in the composite industry. However, the overwhelming proportion of published data has failed to fulfil these expectations and natural fibres currently exhibit, at best, only moderate reinforcement compared to glass fibres. Such results are often explained in terms of the poor interfacial compatibility between many natural fibres and matrix polymers. However, it is also becoming clear that much of the research based on this hypothesis and subsequently on surface and interfacial modification of natural fibres using silanes and other coupling agents is also failing to show substantial, cost effective, improvements in composite performance. In this paper we will discuss and illustrate these effects, including the use of a number of silanes and other coupling agents, with results obtained on injection moulded jute-polypropylene. An explanation will be proposed for the general poor performance of NF composites based on the highly anisotropic structure of the natural fibres and its direct influence on the apparent interfacial shear strength (IFSS) in these systems. Consequently, although remedies for the interfacial performance issues of NF composites are often sought in the chemistry of the system, these results suggest that, for improved reinforcement efficiency, we also need to better understand the role of fibre structure on the apparent IFSS in NF composites. Only by fully understanding the internal structure-performance relationships of these complex composite fibres can we hope to significantly improve the performance levels of NF composites.

Carl Tripp; Laboratory for Surface Science & Technology, Engineering and Science Research Building, University of Maine, Orono, ME 04469

Use of Silanes to Design Materials for Detection of Chemicals and Biological Agents

(Abstract not yet available)

Peng Wang; Chemical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221-0012

The structure and hydrothermal degradation behavior of silane-laced epoxy films were studied by specular neutron reflectivity (NR). The degradation process was investigated by comparing the NR data of the as-prepared dry film with the re-dried film after 10, 24 and 36 hours exposure to 80C liquid water. The addition of bis-sulfur silane altered the hydrothermal degradation behavior of neat epoxy film and improved the hydrothermal stability of neat epoxy film.



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