Abstract: An adhesion promoter for polyimide is provided having the formula: ##STR1## wherein A is ##STR2## Ar is an aromatic group, R.sup.1 is lower alkyl, R.sup.11 is OR.sup.1 or lower alkyl, R.sup.111 is hydrogen or lower alkyl.

Abstract: A fabrication process is disclosed that achieves a higher density carbon-bon article, than the prior art processes by maintaining a vertical temperature gradient in a reservoir of pitch (e.g. 550.degree. C. at the bottom to 250.degree. C. at the top) into which a carbon fiber preform is immersed. The use of the vertical temperature gradient results in a reservoir of hot fluid pitch around the upper end of the preform during pitch impregnation of the preform. This permits the fluid pitch to drain down by gravity into the interstices of the carbon fiber and the hardening pitch below. The next step of the process involves gradually increasing the pitch-hardening temperature from bottom to top to harden the pitch from bottom to top. Thereafter, the impregnated preform is carbonized at high temperature. This method takes advantage of the thermal conductivity of the carbon fibers and does not require extremely high pressures. In fact, a high pressure would be a detriment since it results in closed pores.

Abstract: Organic photochromic materials comprising a photochromic dye and a resinous material can be stabilized with a protective coating which will protect them from deactivation by exposure to moisture, oxygen, various plastic host materials, reactive chemicals or even normal atmospheric conditions. Useful organic photochromic dyes include the spiropyrans, the spirooxazines, the metal dithizonates, the phenazines, the phenothiazines and other known photochromic compositions. Useful resinous materials include vinyl-type thermoplastics, cellulosic materials, polyesters, epoxy resins and aminoplast resins. The encapsulated photochromic materials of the invention comprise an organic photochromic dye in combination with an organic resinous material enclosed within an outer shell of an inorganic material and find use in the preparation of photochromic plastic films, sheets, ophthalmic lenses such as lenses for sunglasses and in camera lenses and filters.

Abstract: An improved method of manufacturing articles containing carbon fibers when the fibers are temporarily plasticized to render them more flexible thereby permitting tortuous mechanical manipulation of the fibers to be carried out with little or no mechanical damage. The improvement comprises exposing the carbon fibers to agents capable of intercalating single crystals of graphite, such as bromine or iodine monochloride which have the effect of plasticizing the fibers by lowering their tensile modulus. While the fiber yarns are appreciably more flexible in the plasticized state, and have a higher elongation-at-break, on removal of the plasticizer they tend to return to their original state but retain a measurable degree of the shape imparted to them.

Abstract: Organic photochromic materials comprising a photochromic dye and a resinous material can be stabilized with a protective coating which will protect them from deactivation by exposure to moisture, oxygen, various plastic host materials, reactive chemicals or even normal atmospheric conditions. Useful organic photochromic dyes include the spiropyrans, the spirooxazines, the metal dithizonates, the phenazines, the phenothiazines and other known photochromic compositions. Useful resinous materials include vinyl-type thermoplastics, cellulosic materials, polyesters, epoxy resins and aminoplast resins. The encapsulated photochromic materials of the invention comprise an organic photochromic dye in combination with an organic resinous material enclosed within an outer shell of an inorganic material and find use in the preparation of photochromic plastic films, sheets, ophthalmic lenses such as lenses for sunglasses and in camera lenses and filters.

Abstract: Inorganic photochromic crystalline particles which are particularly useful in ophthalmic quality plastic host materials are formed for instance utilizing a silver halide crystal whose dimensions lie generally in the range between 30 Angstroms and 10,000 Angstroms. The surface of the silver halide crystal is coated with an inorganic material in an effective thickness to render the coating resistant to diffusion from within and to protect the crystal from interaction with host material. The stabilized coated particles can be introduced by known schemes into plastic host materials in order to form photochromic plastic articles useful in the preparation of films, sheets, filters for cameras, wall panels and ophthalmic lenses and other optical devices.

Abstract: Organic photochromic materials comprise a photochromic pigment stabilized with a protective inorganic coating which serves to protect the pigments from deactivation by exposure to moisture, oxygen, various plastic host materials, reactive chemicals or even normal atmospheric conditions. Useful organic photochromic pigments include the anils, hydrazones, semicarbozones, osazones, sydnones, fulgides and others. Inorganic coatings comprising such materials as zinc oxide, titanium dioxide, aluminum oxide, antimony oxide and silicon dioxide are useful in the preparation of photochromic plastic films, sheets, ophthalmic lenses such as lenses for sunglasses and in camera lenses and filters.