in u s pat nos 2 873 181 3 041 156 3 098 730 4 473 671 and 4 539 048 all incorporated herein by reference there are three major types of coupling agents of particular interest herein silanes titanates and zircoaluminates silanes are by far the most readily available and widely studied useable silane coupling agents generally correspond to the formula x 3 sir 1 y wherein silane coupling agents are discussed in u s pat no 3 079 361 incorporated herein by reference the organofunctional group y may be any of the variety of groups which can react with the resinous adhesive during curing or which are otherwise sufficiently compatible with the resinous adhesive to form an bonding like association therewith organofunctional groups which function as y include amino epoxy vinyl methacryloxy mercapto ureido and methacrylate groups examples of silane coupling agents are described in plueddmann silane coupling agents plemum press new york 1982 incorporated herein by reference the exact nature of the bonding or association between the hydrolyzable group x and the inorganic filler is not fully understood and may differ for various fillers for fillers that contain silica it may be theorized that an si o si linkage occurs via reaction of the hydrolyzable group from the coupling agent with a hydroxyl group on the inorganic filler surface it will be understood that the particular nature of the associative interaction is not critical to the invention and it is not intended that the present invention be limited to any particular theory or type of interaction it is noted however that the nature of the associative.