Silane coupling agents epoxy functional

Silane coupling agents may contribute hydrophilic properties to the interface, especially when amino functional silanes, such as epoxies and urethane silanes, are used as primers for reactive polymers. The primer may supply much more amine functionality than can possibly react with the resin at the interphase. Those amines that could not react are hydrophilic and, therefore, responsible for the poor water resistance of bonds. An effective way to use hydrophilic silanes is to blend them with hydrophobic silanes such as phenyltrimethoxysilane. Mixed siloxane primers also have an improved thermal stability, which is typical for aromatic silicones [42]. 

With aromatic resins, such as those based on bisphenol-A, cured with aromatic or cyclic aliphatic hardeners, it is difficult to prevent gross phase separation without introducing an adequate level of alkoxysUane functionality in the epoxy resin. Many commercially available silane-coupling agents can be used for this purpose. 

Plueddemann et al. [ 20 ] introduced the term coupling agent , which characterizes its function in glass fiber reinforced polyester and epoxy laminates in 1962. Later, the applications of alkoxysilylpropyl- type silane coupling agents on particle-fiUed composite systems were applied to thermoplastics [21]. These had the structure... 

In primer formulations for adhesive bonding of metals, the coupling agents that are most frequently used are those based on epoxy and amine functionalities. Aqueous solutions of aminosilanes have been successfully used for obtaining stable adhesive bonds between epoxy and steel [10] and epoxy and titanium [11,12], while epoxy functional silanes are preferable for applications involving aluminum substrates [13,14], A simple solution of % epoxy functional silane in water is currently used for field repairs of military aircraft [15] where phosphoric acid anodization would be extremely difficult to carry out, and performance is deemed quite acceptable. 

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