Silane coupling agents fillers

The addition—reaction product of bisphenol A [80-05-07] and glycidyl methacrylate [106-91-2] is a compromise between epoxy and methacrylate resins (245). This BSI—GMA resin polymerizes through a free-radical induced covalent bonding of methacrylate rather than the epoxide reaction of epoxy resins (246). Mineral fillers coated with a silane coupling agent, which bond the powdered inorganic fillers chemically to the resin matrix, are incorporated into BSI—GMA monomer diluted with other methacrylate monomers to make it less viscous (245). A second monomer commonly used to make composites is urethane dimethacrylate [69766-88-7]. 

The composition of an epoxide moulding material will greatly depend on the specific application, and this has been discussed at length. ". The resin may be of the epoxide novolac type and there will also be present hardeners, fillers (such as silica), a silane coupling agent, pigment, flame retardant and a wax release agent. 

Various additives and fillers may be employed. Calcium carbonate, talc, carbon black, titanium dioxide, and wollastonite are commonly used as fillers. Plasticizers are often utilized also. Plasticizers may reduce viscosity and may help adhesion to certain substrates. Thixotropes such as fumed silica, structured clays, precipitated silica, PVC powder, etc. can be added. Adhesion promoters, such as silane coupling agents, may also be used in the formulation [69]. 

The possible reaction between silane coupling agents and inorganic fillers are [66-69]... 

Other additives such as silanes, titanates and zirconates are also used to overcome the processing characteristics of silica fillers. Silanes not only give improved processability of silica-filled compounds, but also provide improved crosslinks between the silica particle surface and the rubber molecular chains giving increased physical properties. The use of silane coupling agents at a... 

Fig. 14. Effect of the chemical structure of silane coupling agents on their adsorption on the surface of a CaC03 filler, r=1.25pm (O) aminosilane (AMPTES), (A) aliphatic silane (SPIES)... 

Han [17] has shown that the effect of silane coupling agents on the viscosity of filled thermoplastics is not consistent. Melt viscosity may be decreased or increased depending on the chemical structure of the treatment and the nature of the polymer/filler combination under consideration. These observations probably reflect the effectiveness of the coupling agent in promoting bonding between filler and polymer, and hence the extent of polymer immobilization. 

Many different silane coupling agents are available for improving the adhesion between polymers and metals or fillers and fibers [1]. Although organofunctional silanes have been reported to be very effective in such adhesion applications, the exact mechanism by which they function has not been determined conclusively in certain cases. Several techniques have been used to characterize silane films formed on various substrates, such as glass, aluminum, and steel. Some of these methods are XPS [2, 3], FUR [4], IETS [5, 6], NMR [7], and Raman spectroscopy [8]. 

Weissenbach, K. and Mack, H., Silane coupling agents, in Functional Fillers for Plastics, Xanthos, M. (Ed.), Wiley-VCH, Weinheim, Germany, 2005, Chapter 4, 59-83. 

The organofunctional portion bonds with the resin in the adhesive or the organic medium, and the silane portion bonds to the inorganic or substrate surface. Silane coupling agents are commonly used between the adhesive and the adherend, between resin matrix and reinforcing fibers in composites, and between resin matrix and mineral fillers in compounds. The resulting interface provides... 

Cellulose fillers, with and without silane coupling agent treatment, have been investigated at various levels showing an increase in physical properties and viscosity (53). 

The effectiveness of silane coupling agents is greatest with silica, glass, copper, aluminum, or inorganic oxides, while adhesion to carbon black, mineral sulfate fillers, and some other metals is poorest. 

We investigated the use of the molding resin powder (<150 m) as a filler for construction materials composed of bisphenol A type epoxy resin and amine type hardener, and compared the material properties with those produced with a silica powder filler (<150 fi m). Furthermore, the effect of surface treatment of the molding resin powder on these properties was examined by using epoxy or amino silane coupling agents, which were added at lwt% to the molding resin powder and heated at 100°C for 1 hr. 

Methods of filler pretreatment silane coupling agent... 

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