Abstract: Solvent resistant halogenated aromatic polyester fibers are prepared by first heat treating the fibers at substantially constant length at a temperature of from about 270.degree. to about 295.degree. C. for a period of from about 5 to about 60 minutes, and then further treating the fibers with perchloroethylene which is at a temperature of from about 80.degree. C. up to its boiling point for a period of at least about 15 minutes to produce halogenated aromatic polyester fibers having improved solvent resistance.

Abstract: A blend of discrete polyester and cotton fibers comprising a substantial proportion of polyester fibers (i.e., about 50 to 70 percent by weight polyester fibers based upon the total weight of polyester and cotton fibers) effectively is rendered non-burning while retaining the desirable textile properties (e.g., hand and aesthetic appeal) normally associated with this blend. The polyester and cotton fibers are physically admixed with discrete additive fibers formed from a synthetic aromatic polymer containing chlorine, bromine, or mixtures thereof chemically bound to an aromatic ring which is substantially free of an oxide of antimony (as described), and an organophosphorus flame retardant is topically applied to the resulting blend in a minor concentration (i.e., about 2 to 20 percent by weight based upon the total weight of the fibers of polyester, cotton, and synthetic aromatic polymer).

Abstract: A process for preparing certain halogenated aromatic polyesters having a predetermined molecular weight is provided. Such polyesters are prepared by solution polymerization of an appropriate bisphenol and diacid halide wherein the diacid halide is added to a solution containing the bisphenol until the viscosity of the resulting polymer containing solution reaches a predetermined solution viscosity limit at which time the further addition of diacid halide is terminated. The solution viscosity limit is indicative of the attainment of said predetermined molecular weight. The identification of said solution viscosity limit is achieved by a feedback mechanism wherein the viscosity of the polymer containing solution is monitored or sensed during or after the addition of the diacid halide to the bisphenol containing solution.

Abstract: An assemblage of fibers is provided which exhibits highly satisfactory flame retardant characteristics in spite of the fact that discrete fibers are included within the admixture which would normally burn when exposed to flame. Included in intimate physical admixture with the fibers which would normally undergo combustion are discrete additive fibers consisting primarily of a chlorinated and/or brominated aromatic polymer having the inherent ability to render the admixture as a whole non-burning when subjected to the flame. Particularly preferred additive fibers are formed primarily of an aromatic polyester formed from the reaction of tetrabromobisphenol A, isophthalic acid, and terephthalic acid or the esterforming derivatives thereof. Also, in a particularly preferred embodiment a minor concentration of an oxide of antimony (e.g. antimony trioxide or antimony pentoxide) is intimately dispersed throughout the additive fibers.

Abstract: A process is provided for the efficient conversion of acrylonitrile homopolymer fibrous materials and closely related acrylonitrile copolymer fibrous materials to graphitic fibrous materials of high tenacity. The process incorporates an initial brief fiber healing step which is conducted at a temperature of about 170.degree. to 220.degree.C., a preoxidation step, and a tandem carbonization/graphitization step as described. The relationship of the various variables required to produce the high tenacity graphitic fibrous product is set forth in the equation provided. In a preferred embodiment of the invention the carbonization/graphitization step of the process is conducted on a reliable and stable basis wherein the desired tenacity is achieved without the necessity of resorting to the exertion of high longitudinal tensions upon the preoxidized acrylic fibrous material.