Abstract: Method of retarding age embrittlement of polyester comprising heat treating the polyester after preparation by cooling below 90.degree. C. and then heating at 90.degree. C. to 160.degree. C. within 24 hours of preparation, and a polyester composition in which ageing is substantially retarded compared to the non-heat treated polyester. The invention encompasses the polyester composition which has been subjected to the method.

Abstract: A boron nitride fiber comprising hexagonal and/or turbostratic boron nitride having C planes oriented substantially parallel to the fiber axis and a degree of orientation of 0.74 or above can be obtained by heating an adduct between a boron trihalide such as boron trichloride or the like and a nitrile compound such as acetonitrile, benzonitrile or the like, and an ammonium halide or a primary amine hydrohalide in the presence of a boron trihalide at around 125.degree. C. to form a boron nitride precursor, dissolving the boron nitride precursor in a solvent such as N,N'-dimethyl formamide or the like, capable of dissolving the precursor, spinning the solution to obtain a boron nitride precursor fiber, heat-treating the precursor fiber in an inert gas atmosphere and then in an ammonia gas atmosphere to obtain a boron nitride fiber, and heat-treating the boron nitride fiber with a tensile stress being applied to the fiber. The boron nitride fiber of the present invention has a degree of orientation of 0.

Abstract: A distinctive technique for making porous fiber includes a stretching of a substantially continuous fiber while the fiber is in an operative association with an effective quantity of surface-active material. The fiber can be produced from a source material which includes a thermoplastic, orientable material and at least about 0.35 weight percent (wt %) of a supplemental material. In particular configurations of the invention, the fiber may be contacted with a first quantity of surface-active fluid and at least a separate, second quantity of surface-active fluid. In other configurations, the fiber may be subjected to an additional incremental stretching.

Abstract: A lactic acid polymer composition comprising formulating 100 parts by weight of a mixture consisting of 80-95% by weight of an L-lactic acid polymer having an L-lactic acid proportion of 75% or more and 5-20% by weight of a plasticizer selected from the group consisting of a polyhydric alcohol ester and a hydroxypolycarboxylic acid ester, 0.1-5 parts by weight of an anti-bloking agent having a SiO.sub.2 content of 90% or more and an average particle size of 7-50 nm, and 0.1-2 parts by weight of a slip agent; a molded product and film obtained from the composition; and a preparation process of the same are disclosed. The molded product and film are excellent in processability, transparency, flexibility, anti-blocking property and slip, and can be degraded into harmless water and carbon dioxide under natural environment, when abandoned.

Abstract: A process for eliminating post-molding fabric curl and distortion in molded fabrics and fabrics produced thereby. The molded fabrics are laminates including a non-woven fabric face and a binder layer and/or sheet backing. Post-molding curling and distortion can be eliminated by maintaining heat on the face fabric until the backing has been cooled enough to be rigid.

Abstract: The present invention relates to a method for eliminating surface irregulties on the wraparound window of a torpedo nose array. The method broadly comprises the steps of preheating an oven to a temperature in the range of from about room temperature to about 160.degree. F., placing the nose array with the surface irregularities in the preheated oven, applying a vacuum at a pressure of up to about 10 mm of mercury, and maintaining the object in the oven under the conditions of temperature and pressure for a time sufficient to cause polymerization at the surface of the object and removal of gas bubbles, waves and blisters from the surface of the nose array. The method further comprises introducing an anhydrous gas such as nitrogen into the oven during the vacuum applying step.

Abstract: A polyester base film for magnetic recording media having improved adhesion to the magnetic layer applied thereon as well as good abrasion and scratch resistance prepared by melt-extruding a polyester resin containing inorganic and organic particles to form a sheet; extending the sheet; and heat-setting the extended film, wherein the heat-setting step is carried out by heat-treating a first surface of the film, which is to be coated with a magnetic material, at a temperature ranging from 170.degree. to 290.degree. C. for 1 to 50 seconds so that the crystallinity thereof ranges from 50 to 70% and heat-treating the other surface of the film at a temperatue which is lower than the first heat-treatment temperature by 20.degree. C. or more for 1 to 200 seconds so that the other surface attains a crystallinity which is lower than that of the first surface by at least 5%.

Abstract: Single crystal sapphire is conventionally employed for mid-wave IR windows and domes exposed to high aerodynamic heating environments. Single crystal sapphire, however, suffers a loss of compressive strength in the c-axis of 95% on heating from ambient to 800.degree. C. This loss of compressive strength on heating results in poor thermal shock resistance. Poor thermal shock resistance jeopardizes the reliability of the windows and domes. The process of the present invention strengthens sapphire and improves its resistance to thermal shock by introducing magnesium (Mg) ions into the crystal lattice of sapphire to form a solid solution. The solid solution increases the strength of the sapphire. Additionally, a larger increase in strength results from converting the Mg into second phase precipitates comprising magnesium aluminate spinel.

Abstract: A process for producing a hollow or sheet molded product having a superior appearance is provided, which process is characterized in that a multi-layer molded product having a surface layer (A) of a propylene random polymer of m.p. of 100.degree. to 150.degree. C. having a thickness of 1 to 20% of that of the molded product, and a substrate layer (B) of a thermoplastic resin of a m.p. higher than that of the propylene random polymer is formed and the surface layer (A) is heat-treated into a molten state, followed by immediately cooling to form a smooth surface.

Abstract: Aramids which after drawing have high tensile strengths and tensile moduli are made from units derived from selected 2,2'-disubstituted-4,4'-diaminobiphenyls, p-phenylenediamine, oxydianiline and terephthalic acid. Also disclosed is a process for drawing such aramids at least 1.5%, which results in the drawn aramid having significant crystallinity and higher tensile strength. The aramids are useful for ropes and composites.

Abstract: To improve the re-wrappability of the expander members used on balloon catheters subsequent to an initial inflation thereof, the balloon member is subjected to an annealing process in which the balloon member, in its wrapped configuration, is placed within a plastic sheath and it, together with the sheath, is then placed between the jaws of a clamping fixture where the jaws may be heated to a predetermined temperature. When the jaws are made to close on the sheath and the wrapped balloon contained within it, the wrapped balloon is subjected to a radial compressive pressure and a temperature approximately equal to or above the glass transition temperature for the balloon material utilized and then maintained at that temperature for a predetermined time interval. The annealing is found to introduce a memory component into the plastic of the balloon that causes it to assume a lower profile upon deflation than otherwise obtained.

Abstract: A process for preparing a thermoplastic resin film having uniform physical and chemical properties includes extending a thermoplastic resin sheet in a longitudinal direction so that the crystallization energy of the longitudinally extended sheet is 20 J/g or more to give a longitudinally extended sheet, extending the longitudinally extended sheet in a transverse direction to give a biaxially extended film, and heat treating the biaxially extended film to give the resin film.

Abstract: The present invention provides a method for making medical devices, especially stents, catheters, cannulas, plugs and constrictors, by treatment of ionically crosslinkable polymer compositions with crosslinking ions.

Abstract: A method is provided for creating a plastic component constructed, at least in part, from polychlorotrifluoroethylene, having improved properties. The method creates a component from a composition that has polychlorotrifluoroethylene, heats the component to a temperature that is greater than the melting point of the composition, and rapidly quenches the component in a cold medium.

Abstract: A method of manufacturing a bobbin made essentially or partially of a curable resin comprises the steps of: a) providing a mold consisting of a male portion and of a female portion, the gap left between the said female and the male portions, in their operational mounted position, being of the shape and dimensions of the bobbin which it is desired to produce, the mold being provided with a resin inlet and vacuum port in communication with the gap; (b) laying on the surface of the male part of the mold, or winding thereon, any element or material which it is desired to embed within the resin; c) inserting the male part of the mold into the female part thereof and securely connecting the two parts, the two parts, when connected, being essentially sealed against pressure loss along their contact surfaces; d) causing a curable resin to flow into the gap through the resin inlet, while applying a vacuum at the vacuum port, until the empty space provided within the gap is substantially entirely filled with resin; e)

Abstract: A process for the simultaneous drying and crystallization of crystallizable thermoplastic synthetic material (plastic), e.g. polyethylene terephthalate, in which plastic from the melt is extruded in cord form, solidified at the surface by quenching in water and crystallized by gas treatment and dried, using a device for cooling and drying the cord emerging from dies having a casting gutter with its acceptance end arranged beneath the dies and a device producing a flow of coolant on the casting gutter within a quenching section, a subsequent dewatering section in which the casting gutter has apertures for the free flow of the coolant, a subsequent drying section in which the casting gutter has closely spaced nozzles for the passage of gas and a granulator downstream of the drying section. The lengths of the quenching, dewatering and drying sections must be such, taking account of the rate of creep of the cord along the casting gutter, that the passage time in the quenching section is a maximum of some 1.

Abstract: Disclosed herein is a perpendicular magnetic film comprising a spinel thin film which is formed on a substrate, which contains Fe as the main ingredient and further contains Co and Ni, and which has a coercive force of less than 3000 Oe, the plane (400) thereof being predominantly oriented in parallel with said substrate, the spacing of the plane (400) being not more than 2.082 .ANG., the molar ratio of Co to Fe being 0.005 to 0.32 and the molar ratio of Ni to Co being at least 0.6.

Abstract: A method and apparatus for forming an article from a sheet of PET material of thickness greater than 1 mm comprises heating the PET sheet to a preforming temperature of approximately 110.degree. C. by heaters, and then forming the sheet onto a heated vacuum mold. The sheet is retained in the mold by the vacuum and the surface of the sheet are maintained at a temperature of approximately 160.degree. C. by the mold and the heater, respectively, until the degree of crystallization of the sheet is in the order of 35%.

Abstract: A method of producing a silicon nitride ceramic component, comprising: grinding a silicon nitride sintered body comprising .alpha.--Si.sub.3 N.sub.4 having an average grain size of 0.5 .mu.m or smaller and .beta.'-sialon having an average grain size of 3 .mu.m or smaller in major axis and 1 .mu.m or smaller in minor axis into a predetermined size with a surface roughness of 1-7 .mu.m in ten-point mean roughness; heat treating the same at temperature range of 800.degree.-1200.degree. C. in the air; and standing it to allow to be cooled, whereby providing a residual stress in the ground surface before and after the heat treating as a residual compressive stress at a ratio of 1 or higher of the residual compressive stress after the heat treating to that before the heat treating (residual compressive stress after the heat treating/residual compressive stress before the heat treating), preferably 5 or more.

Abstract: A polyester support prepared by the step of subjecting a polyester film to bulk rolling and heating the bulk rolled polyester film to a temperature of from 50.degree. C. to the glass transition point of said polyester film, or subjecting a polyester film to bulk rolling at a temperature of from 50.degree. C. to the glass transition point of said polyester film, resulting in the polyester support, wherein the glass transition point of said polyester film is 90.degree. to 200.degree. C., and wherein the step of bulk rolling has a start tension of 3 to 75 kg/m per unit width of the polyester film and an end tension of 3 to 75 kg/m per unit width of the polyester film.

Abstract: A method for heat treating a rolled polyester support at a temperature lower than the glass transition temperature (Tg) is disclosed, wherein the polyester film is wound around a core to have a difference in roll diameter of 10% or less and then heat treated to render the film surface smooth. Further disclosed are a photographic polyester support which is subjected to heat treatment according to the above-described method, a silver halide photographic material which uses the above-described polyester support and a polyester support having a creak value of from 10 to 600 g.

Abstract: A process for preparing a biaxially oriented thermoplastic resin film which comprises: extending a thermoplastic resin sheet in a longitudinal and a transverse directions to form a film thereof, and heat treating the film under a temperature gradient descending from both edges to the center of the film along the transverse direction within a zone defined by the following formula (1) by employing a heater which is located over the film with an angle .theta. of the following formula (3) from said both edges to the center of the film to produce a thermoplastic resin film having uniform physical end chemical properties in the transverse direction:0.25.ltoreq.L.sub.1 /W.ltoreq.0.9 (1)tan.theta.=W/2L.sub.1 (3)wherein:L.sub.1 is the distance from the end point of the transverse extending to the end point of the heat treating; andW is the total width of the film.

Abstract: A device for manufacturing expandable polystyrene (EPS) pellets includes a continuous process extruder, a die, a pelletizer and a hot water annealing quencher assembly. The pelletizer cuts strands of EPS material extruded from the extruder and die into uniform EPS pellets. The annealing quencher assembly includes a quencher tank, a water vortex substantially immersed therein for generating a slurry of water and EPS pellets discharged from the pelletizer, a quenching loop, and a slurry pump for pumping the slurry from the water vortex through the quenching loop to thereby anneal the EPS pellets.

Abstract: A biaxially oriented polyester film with excellent levelling property is produced by the inventive process which comprises: (a) melt-extruding and extending biaxially a polyester resin to shape it into a film; (b) treating the film thermally under a condition that formulae (1), (2) and (3) are satisfied; and (c) relaxing the film at a temperature range of Tm-60.degree. C. to Tm-140.degree. C. during the step (b):Tm-60.degree. C.<T1<Tm-10.degree. C. (1)50<T1-T2<100 (2)5<(T1-T2)/t<25 (3)wherein:Tm represents the melting point of the film (.degree.C.),T1 represents the initial temperature for the thermal treatment of the film (.degree.C.),T2 represents the terminal temperature for the thermal treatment of the film (.degree.C.), andt represents time for the thermal treatment (sec.).

Abstract: Disclosed herein is a method for controlling sapstain in wood and wood products comprising a) steam pasteurizing the wood or wood product followed by b) treating the wood or wood product with a biological control agent comprising one or more fungi selected from the class Hyphomycetes. Also disclosed are wood or wood products so treated.

Abstract: A process for direct bonding similar or dissimilar materials at low temperatures in which a material surface is rendered hydrophilic and reactive by creating nitrogen based radicals on the surface, the surface is direct bonded to a second surface, and the bonded surfaces are annealed at a temperature below approximately 500.degree. C. A nitrogen based constituent is combined with an activator to render the surface hydrophilic and reactive through ammonia plasma activation or activation by use of hydrofluoric acid.

Abstract: A method of making a count probe for counting particles comprises the following steps. A count wafer is formed along with a core member having an opening for accepting the count wafer. The count wafer is applied to the opening in the core member to form an interference fit between the count wafer and the core member. After application of the count wafer to the opening in the core member, the core member is annealed to relieve stress in the core member.

Abstract: A process of producing a styrene polymer molding which comprises heat treating a molding of a crystalline styrene polymer having mainly a syndiotactic configuration and having a crystallinity of at least 10% as determined by X-ray diffraction analysis. The heat treating is carried out at a temperature of 150.degree.to 250.degree. C. for 20 seconds to 90 minutes.

Abstract: A process for reducing stresses and strains of thermoplastics is described wherein the process includes the step of heating the outer layer of the thermoplastic with a heat source to produce a resin having favorable physical and chemical properties.

Abstract: A post-coalescence melt-spinning process for preparing fine undrawn hollow polyester filaments having excellent mechanical quality and uniformity at high speeds (2-5 km/min) involving selection of polymer viscosity and spinning conditions, whereby the void content of the resulting new undrawn filaments is essentially maintained or increased on cold-drawing or hot-drawing with or without post heat treatment, and the new fine hollow polyester filaments obtained thereby.

Abstract: A method for forming a surgical clip and fixture for use therein includes molding a polymeric clip body, the clip body having hinged legs, the polymer of the clip body being substantially amorphous. The clip body can then be moved to a desired configuration while being subjected to a temperature above the glass transition temperature. The molded clip body is then heated to a temperature within the crystallization range for a period of time sufficient to impart at least 20% crystallinity thereto to impart a spring back property. Also disclosed herein is a fixture for forming a surgical clip in accordance with this method.

Abstract: A process for producing a hollow or sheet molded product having a superior appearance is provided, which process is characterized in that a multi-layer molded product having a surface layer (A) of a propylene random polymer of m.p. of 100.degree. to 150.degree. C. having a thickness of 1 to 20% of that of the molded product, and a substrate layer (B) of a thermoplastic resin of a m.p. higher than that of the propylene random polymer is formed and the surface layer (A) is heat-treated into a molten state, followed by immediately cooling to form a smooth surface.

Abstract: A simplified and more efficient process is described for drying (and heat-treating) a lyotropic polybenzazole film in which the film is constrained in only the machine direction during drying (and heat-treating). The amount of stretching in the transverse direction the film undergoes prior to it being coagulated can be increased to compensate for the relaxation of the film during the drying process and the lack of stretching during the heat-treating process. Films made in this manner have acceptable finished properties.

Abstract: A method and an apparatus to thermocrystallize amorphous thermoplastic material in a bottom portion (11) of a preform (10) while producing a container. By means of at least one heating device (20, 30) the plastic material is heated to an elevated temperature at which the material crystallizes thermally. The supply of energy is discontinued once the material crystallizes at a speed entailing that the thus released effect corresponds to or exceeds that effect which departs from the material undergoing crystallization. The apparatus includes a mandrel (26) having a forming surface (24) which at an increased temperature is brought into abutment against a defining surface (18) of the bottom potion. The forming surface has a curvature which deviates from the curvature of the defining surface (18) so that during the initial phase of the abutment the forming surface is abutting against the defining surface only in a central area thereof.

Abstract: A polymer composite includes a thermoplastic plastic polymer having a fine grain metal or metal oxide dispersed therein. Preferably, the fine grains has a size of about 1,000 nm or less. A method of making the polymer composite by adhering a metal layer to a thermoplastic polymer layer in a thermodynamically nonequilibrated condition followed by relaxation of the polymer layer to obtain thermodynamic equilibrium which causes the metal layer to be absorbed by the polymer layer as fine grains is also disclosed.

Abstract: Improved polybenzoxazole fibers are made by a process for finishing a spun and drawn dope fiber, which contains polybenzoxazole polymer and polyphosphoric acid, including the steps of:(a) coagulating the dope fiber in an aqueous coagulant;(b) washing the coagulated fiber with an aqueous washing fluid for less than 72 hours under conditions such that the fiber contains no more than 8,000 ppm residual phosphorus (1 ppm=1 part per million, by weight);(c) drying the fiber at a temperature of no more than 300.degree. C. until it retains no more than about 3 weight percent residual moisture; and(d) heat-treating the fiber at a temperature of at least about 300.degree. C. under tension.

Abstract: A fiber of a polyester, in which 80% or more of the repeating units are composed of ethylene terephthalate, characterized in that it satisfies the following inequalities:0.16<tan .delta..sub.max <0.22 1115<T.sub.max <140 2D.sub.100 <-3.79.times.d.sup.1/2 +91 3D.sub.130 >-11.36.times.d.sup.1/2 +58 4as well as a process for the production and dyeing of a fibrous structure of the polyester fiber.According to the present invention, especially in deep color dyeing at a high temperature, the degree of dye exhaustion is improved, and the utilization efficiency of the dye is enhanced, and moreover, especially in an extremely fine fiber yarn, a polyester fibrous structure having a concentration of a color shade equal to that of an ordinary yarn, which has never been obtained by the conventional process can be provided. In addition, there can be provided a polyester fiber and a fibrous structure thereof that are excellent in coloring properties and color fastness and can be used for various purposes.

Abstract: Hollow polyester undrawn filaments having excellent mechanical quality and uniformity are prepared by a simplified post-coalescence melt spinning process at speeds of e.g. 2-5 km/min by selection of polymer and spinning conditions whereby the void content of the undrawn filaments can be essentially maintained or even increased when drawn cold or hot, with or without post heat-treatment.

Abstract: A heating device used for production of a disc shutter made of synthetic resin and shaped into a U-form in section, arranged to heat a pair of corner portions of the shutter to extinguish residual stresses that exist in the corner portions that are formed where a connecting portion of the shutter connects a pair of shutter plates. The heating device comprises a movable support for fixedly supporting the free ends of the pair of shutter plates, a fixed heater which heats the corner portions of the shutter at a predetermined temperature, a pair of heating surfaces connected to form an acute angle, a temperature setting device, and a heating duration setting device.

Abstract: Blow molding processes for the manufacture of polyethylene terephthalate (PET) containers are disclosed. The containers are capable of withstanding, without appreciable deformation, relatively severe thermal conditions encountered during processing by filling with a hot liquid or pasteurization of the contents of the container. A representative process includes the steps of blow molding the heated body of an amorphous PET preform comprising a body and a neck section having a body with dimensions greater than the dimensions of the final PET container to be formed; heating only the body of the intermediate container under specified conditions to rapidly shrink the body, thus forming a contracted body; heating the neck section to effect crystallization thereof; slowly cooling the neck section alone while heating of the contracted intermediate body continues; and blow molding the heated contracted body of the intermediate container in a second mold to its final shape and dimensions.

Abstract: A fluorochemical graft copolymer comprising: a base polymer comprising polymerized units derived from monomers having terminal olefinic double bonds, having a moiety comprising a fluoroaliphatic group grafted thereto. Also disclosed are processes for preparing such fluorochemical graft copolymers, forming and annealing methods for enhancing the surface activity of such a graft copolymer, polymer blends comprising such a fluorochemical graft copolymer and a matrix polymer that is miscible with the base polymer, and a method for reducing the surface energy of a polymer comprising polymerized units derived from monomers having terminal olefinic double bonds.

Abstract: A catheter is formed from a single extrusion of cold crystallizable material in its amorphous state. Selected portions of the catheter are subsequently subjected to the material's cold crystallization temperatures for a selected period of time in order to transform those portions into a more crystalline form. Increased crystallinity profoundly affects the physical characteristics of the material. A jointless catheter having a relatively stiff body and a soft, pliable, and atraumatic tip is thereby provided.

Abstract: A casting is formed by inserting a metal reinforcement coil into a mold cavity and injecting a plastic casting material into the cavity such that the coil becomes embedded within the plastic casting material. Prior to being placed in the cavity, the coil is heat treated to relieve stresses therein, and a layer of plastic is sintered to the outer surface of the coil. Plastic is injected into the mold at a temperature lower than the heat-treating temperature, but hot enough to melt an outer portion of the layer and become joined therewith. An inner portion of the layer remains sintered to the coil.

Abstract: A process for dimensionally stabilizing an article molded from a synthetic resin material, such as PVC. The molded article is subjected to a first cooling treatment to cool the article at a temperature lower than the glass transition temperature Tg of the synthetic resin followed by a heating treatment at a temperature higher than the glass transition temperature Tg and then is subjected to a second cooling treatment again at a temperature lower than the glass transition temperature Tg. Following such treatment steps, the molded article, such as side molding for automobiles, have less variation in dimensions and less shrinkage after molding in use.

Abstract: Improved polybenzoxazole fibers are made by a process for finishing a spun and drawn dope fiber, which contains polybenzoxazole polymer and a solvent acid, including the steps of: (a) coagulating the dope fiber in an aqueous coagulant: (b) washing the coagulated fiber with an aqueous washing fluid for less than 72 hours under conditions such that the fiber contains no more than 8,000 ppm residual solvent acid (1 ppm=1 part per million, by weight); (c) drying the fiber at a temperature of no more than 300.degree. C. until it retains no more than about 2 weight percent residual moisture; and (d) heat-treating the fiber at a temperature of at least about 300.degree. C. under tension.

Abstract: Processes for producing oriented films of semicrystalline thermoplastic polymers, such as polyimides, and films produced thereby are disclosed. One process includes partial crystallization or imidization, orientation and further crystallization or imidization. Another process includes rendering a film of semicrystalline thermoplastic polymer amorphous, orienting the film and introducing crystallinity.

Abstract: An aromatic sulfide/ketone polymer is prepared from a dihaloaromatic ketone, alkali metal sulfide, water and a polar organic compound. The polymerization reaction mixture is subjected to a heat soak at an elevated temperature, then a separation agent is added under controlled conditions and the mixture is subsequently cooled to provide a mixture comprising particulate aromatic sulfide/ketone polymer. Biaxially-oriented film is made from the recovered particles of aromatic sulfide/ketone polymer by (1) washing the polymer particles with an aqueous calcium salt, (2) heating the washed particles to remove water, (3) molding the heated particles to form a sheet of polymer, (4) biaxially stretching the sheet above the glass transition temperature of the polymer to form a film, and (5) heat-setting the biaxially-oriented film under stretching tension for a time and at a temperature to increase strength properties and density.

Abstract: Spherulites grow in such sections as neck, neck end, bottom center or bottom periphery of a hollow bottle-shaped container of biaxially oriented blow-molded polyethylene terephthalate where the resin is not substantially subjected to orientation, thereby to improve the thermal resistance, stiffness and content resistance of such sections to almost the same extent as the biaxially oriented sections of the container such as shoulder and cylindrical sections thereof. The aforesaid sections of the preformed piece before being blow-molded or of the blow-molded container where the resin is not substantially subjected to orientation are first heated at 120.degree.-180.degree. C. for 3-8 minutes and, then, annealed at room temperatures, with a result that such sections have a spherulite texture of an increased density and are opacified in white or milky white.

Abstract: Pyrolytic carbon products are manufactured so as to have improved structural properties. Pyrolytic carbon is deposited on a substrate in a fluidized bed of small particles at a temperature of about 1200.degree. to about 1400.degree. C., and after cooling to ambient temperature, the pyrolytic carbon is machined to desired physical dimensions for a heart valve component or the like. By heating such pyrolytic carbon structures in an inert gas atmosphere to a temperature in the range of about 1000.degree.-1500.degree. C. for at least about one hour following machining, it is found that stresses created in the pyrolytic carbon as a result of the machining are relieved without adverse effect to mechanical properties of the pyrocarbon, resulting in components having greater structural integrity.

Abstract: Stretched surface recording disk (SD) 10 comprises an annular support 12 having raised annular ridges 42 and 28 at its inside and outside diameters 22 and 30 with a base portion 24 in between the two ridges, and an annular recording medium film 14 held in radial tension and stretched across the base portion by adhering the film to attachment surfaces 48 and 36 near the inside and outside diameters respectively. The SD is annealed twice during manufacture to relieve stress in the stretched film 14. This annealing results in SD essentially free from track anisotropy and stress distribution anisotropy in the plane of the disk. As a result, data tracks are more stable than in previous SD, track density can be greater, and the SD is generally more reliable.