Abstract: Fusible polyimide powders are prepared by the process of this invention. An amic acid amine is first prepared by treating equimolar amounts of a 2,2-bis[4-(aminophenoxy)phenyl]-hexafluoropropane with an unsaturated carbocyclic monoanhydride. The amic acid amine is then mixed with an aromatic tetracarboxylic dianhydride and the mixture heated to form a polyimide precursor. A chemical dehydrating agent is added in an amount sufficient to substantially, fully imidize the precursor. The resulting fusible polyimide powder is finally separated.

Abstract: Described is a process for producing, in particulate form, aromatic polyimides based on one or more 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropanes. The process involves forming a solution of an equimolar mixture of (1) an aromatic tetracarboxylic dianhydride and (2) a 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane as the sole or predominant aromatic diamine in (3) a solvent composed of (i) tetrahydrofuran, or (ii) one or more alkyltetrahydrofurans having a normal boiling point below 100.degree. C., or (iii) a mixture of (i) and (ii), and heating and agitating such solution in a closed reaction system under super-atmospheric pressure such that a separate phase of particulate aromatic polyimide is formed. The process avoids difficulties caused by the tendency of the wet polyimide polymer to agglomerate into stringy or tacky masses which can foul reactor and agitator surfaces.

Abstract: A polymer of monoallylamine, preferably a water-soluble polymer of monoallylamine, whether in free (i.e., unneutralized) form or in salt (i.e., partially or completely neutralized) form is used in conjunction with a sulfonated polymer such as a water-soluble lignosulfonate, condensed naphthalene sulfonate, or sulfonated vinyl aromatic polymer, to minimize fluid loss from the slurry during subterranean well cementing operations. The polymer of monoallyl amine may be a homopolymer or a copolymer, and may be crosslinked or uncrosslinked. These components interact with each other in the presence of water to produce a gelatinous material that tends to plug porous zones and minimize premature water loss from the well cement slurry when present in the subterranean well formation. In addition, the gelatinous material so formed prevents de-stabilization of the slurry in the well formation.

Abstract: A polymer of monoallylamine, preferably a water-soluble polymer of monoallylamine, whether in free (i.e., unneutralized) form or in salt (i.e., partially or completely neutralized) form is used in conjunction with a sulfonated polymer such as a water-soluble lignosulfonate, condensed naphthalene sulfonate, or sulfonated vinyl aromatic polymer, to minimize fluid loss from the slurry during subterranean well cementing operations. The polymer of monoallyl amine may be a homopolymer or a copolymer, and may be crosslinked or uncrosslinked. These components interact with each other in the presence of water to produce a gelatinous material that tends to plug porous zones and minimize premature water loss from the well cement slurry when present in the subterranean well formation. In addition, the gelatinous material so formed prevents de-stabilization of the slurry in the well formation.

Abstract: A polymer of monoallylamine, preferably a water-soluble polymer of monoallylamine, whether in free (i.e., unneutralized) form or in salt (i.e., partially or completely neutralized) form is used in conjunction with a sulfonated polymer such as a water-soluble lignosulfonate, condensed naphthalene sulfonate, or sulfonated vinyl aromatic polymer, to minimize fluid loss from the slurry during subterranean well cementing operations. The polymer of monoallyl amine may be a homopolymer or a copolymer, and may be crosslinked or uncrosslinked. These components interact with each other in the presence of water to produce a gelatinous material that tends to plug porous zones and minimize premature water loss from the well cement slurry when present in the subterranean well formation. In addition, the gelatinous material so formed prevents de-stabilization of the slurry in the well formation.

Abstract: An apparatus for reducing the vinyl chloride monomer content of polyvinyl chloride resins suspended as a slurry in an aqueous medium. The polyvinyl chloride-water slurry as produced in a conventional suspension resin autoclave, or a resin-water slurry prepared subsequent to suspension polymerization, is placed in a vessel and heated to a suitable temperature for removal of vinyl chloride monomer from the resin. In this operation, the polyvinyl chloride-water slurry is agitated in a vessel and steam is injected directly into the slurry to rapidly heat the slurry up to a minimum temperature of at least about 180.degree. F. The slurry is cooled immediately, or optionally it can be maintained for a period of time at the selected maximum temperature and then rapidly cooled by applying vacuum to the vessel and condensing the vapor phase removed from the vessel. Dried polyvinyl chloride resin produced by this process has been found to have a vinyl chloride monomer content below a detectable limit of 0.5 ppm.

Abstract: A method for reducing the vinyl chloride monomer content of polyvinyl chloride resins. The polyvinyl chloride-water slurry is placed in a vessel, and heat is applied to the vessel for a sufficient time to raise it to a suitable temperature for removal of vinyl chloride monomer from the resin. The resin slurry is agitated and also subjected to a vacuum to reduce the temperature during the heat stripping step. In a preferred method, the polvinyl chloride-water slurry is agitated in a closed vessel, heat is applied to rapidly heat the slurry to a temperature of at least about 50.degree. C, and vacuum is applied to the vessel. The slurry is then rapidly cooled by suitable means. The slurry is then dewatered and dried. Dried polyvinyl chloride resins produced by this process have been found to have a vinyl chloride monomer content below a detectable limit of about 2.0 ppm.

Abstract: A method for reducing the vinyl chloride monomer content of polyvinyl chloride resins suspended as a slurry in an aqueous medium. The polyvinyl chloride-water slurry as produced in a conventional suspension resin autoclave, or a resin-water slurry prepared subsequent to suspension polymerization, is placed in a vessel and heated to a suitable temperature for removal of vinyl chloride monomer from the resin. In this operation, the polyvinyl chloride-water slurry is agitated in a vessel and steam is injected directly into the slurry to rapidly heat the slurry up to a minimum temperature of at least about 180.degree. F. The slurry is cooled immediately, or optionally it can be maintained for a period of time at the selected maximum temperature and then rapidly cooled by applying vacuum to the vessel and condensing the vapor phase removed from the vessel. Dried polyvinyl chloride resin produced by this process has been found to have a vinyl chloride monomer content below a detectable limit of 0.5 ppm.