Cyanoacrylate compositions which employ fumed silicas treated with polydimethylsiloxane or trialkoxyalkylsilane are stable and exhibit an unexpectedly high thixotropic ratio. Such compositions are useful in adhesive applications or, when stabilized so as to prevent polymerization in contact with moisture, in latent fingerprint developing applications.

A cyanoacrylate adhesive composition thickened by a copolymer or terpolymer resin capable of being dissolved or solvated by the cyanoacrylate monomer exhibits significantly improved peel strength. Storage stability is also enhanced. Preferred thickeners are acrylonitrile-butadiene-styrene terpolymers, methacrylate-butadiene-styrene terpolymers, and vinylidene chloride-acrylonitrile copolymers. Preferred monomers are methyl and ethyl cyanoacrylates.

This invention relates to a system for forming a composite from a cyanoacrylate composition and a filler within depressions, holes, cracks or spaces in a substrate. The system also allows for the placement of a cantilevered member in the filled depression, hole, crack or space in the substrate to support a load when the cyanoacrylate has cured.

Filled cyanoacrylate adhesive compositions possessing electro- and heat-conducting properties have been developed. These compositions are recommended for panel wiring of electro- and radioelements and hermetic sealing of aluminum casting.

The influence of type and size of filler particles and viscosity of the cyanoacrylate component on the volume resistivity, conductivity mechanism and adhesive strength of the resultant bond has been investigated. Various carbon and metal fillers were used to make conductive cyanoacrylate adhesive compositions and the best results were obtained when Ag, Ni or Mo powders (5–10 μm) were incorporated in thickened ethyl 2-cyanoacrylate with a viscosity of 50–100 cP

The introduction of high molecular weight poly(methyl methacrylate) or poly(butadiene-co-acrylonitrile) into ethyl 2-cyanoacrylate produced viscous adhesives with a homogeneous or heterogeneous structure after cure. Steel joints bonded with these adhesives are shown to have improved tensile shear strength, deformability and stress relaxation of bonds compared with pure cyanoacrylate adhesive. Poly(methyl methacrylate)-modified adhesive is recommended for static load-bearing joints while poly(butadiene-co-acrylonitrile)-modified adhesive is more suited to cyclic or vibrating loads.

Surface-conforming materials, such as sheets, ribbons, tapes or moldable material may be adhered to a wide variety of underwater target surfaces with a cyanoacrylate adhesive. The cyanoacrylate adhesive is evacuated from it container under water, applied to a surface of the surface-conforming material, and then the surface-conforming material is pressed against the target surface for a relatively short period of time. The method provides a method, for example, of attaching a plastic explosive to the hull of a ship entirely under water.

Objects may be bonded to target surfaces of a variety of materials, including rough surfaces, surfaces at temperatures down to -40.degree. F. and surfaces submerged under water, by securing a sheet of compliant material to the object, applying cyanoacylate to the exposed surface of compliant material and pressing the object against the target surface for a time sufficient to establish a cure of the cyanoacrylate adequate to support the object from the target surface.

Pastes of alpha-cyanoacrylic acid esters and insolluble fillers can be applied to surfaces submerged in water for securing thereto, in situ, a wide variety of metallic and non. metallic substances.

Pastes of alpha-cyanoacrylate acid esters and insoluble fillers can be applied to surfaces submerged in water for securing thereto, in situ, a wide variety of metallic and non-metallic substances.