Abstract: Proposed is a method for the preparation of a monolithically integrated composite cured body consisting of a part of cured silicone rubber composition and a part of a silicone-epoxy resin composition firmly bonded together without using any primer or adhesive by first curing either one of the compositions in a metal mold and then bringing the other of the compositions into direct contact with the already cured part in the metal mold to be cured thereon. Firm bonding between the parts can be obtained when the silicone rubber composition is of the peroxide-curable or the hydrosilation-curable type and the silicone-epoxy resin composition comprises:(a) a curable epoxy resin;(b) an alkenyl group-containing organopolysiloxane;(c) an organohydrogenpolysiloxane;(d) an organosilicon compound having at least one silanol group in a molecule;(e) an organic aluminum compound such as aluminum benzoate; and(f) a compound of a platinum group metal such as chloroplatinic acid, each in a specified weight proportion.

Abstract: A method for the casting of highly filled plastics containing polymethyl methacrylate, the method involving:preparing a filler suspension by combining from 30 to 80 wt %, based on the amount of filler suspension, of at least one particle-shaped, inorganic filler with a polymer precursor under high-speed stirring, wherein the polymer precursor is made from methyl methacrylate and a polymethyl methacrylate prepolymer, wherein the filler suspension further contains from 1 to 20 parts by weight, based on the amount of filler suspension, of a colored, filled, comminuted polymer material having a density precisely adapted to the density of the filler suspension and wherein the comminuted polymer material contains a polymer component which is highly crosslinked; andpolymerizing the filler suspension by contacting the filler suspension with at least one radical initiator.

Abstract: A process for preparing thermoset composite articles under relatively mild conditions includes exposing a laminate containing a partially-cured thermosettable resin and a fibrous substrate to an elevated temperature which increases over time, the elevated temperature being below the glass transition temperature of the resin but sufficient to promote further curing and increase the glass transition temperature thereof to the ultimate glass transition temperature of the resin. The temperature of exposure is generally increased at a rate which maintains the temperature within about 20.degree. C. below the glass transition temperature of the thermoset-table resin, so that cure of the resin proceeds in the glassy state. The pressure during the process is generally maintained below about 50 psi and is preferably atmospheric pressure. The process enables the production of thermoset composite articles suitable for high-performance applications without lengthy autoclave treatments.

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: The invention relates to a process for preparing a composite tubular article consisting of a vulcanized elastomer containing carboxylic acid or dicarboxylic acid anhydride functional groups, which is used in combination with a thermoplastic elastomer containing polyamide blocks. The composite tubular article is prepared such that it consists of an inner layer of thermoplastic elastomer containing polyamide blocks sheathed by extrusion at an appropriate temperature with an elastomeric composition comprising a synthetic or natural elastomer containing carboxylic acid or dicarboxylic acid anhydride functional groups, a crosslinking system and optionally various adjuvants and fillers. Optionally, an innermost layer consisting of a thermoplastic with good liquid-barrier properties is present. The composite tubular article obtained is vulcanized, preferably at a temperature of between -5.degree. C. and +30.degree. C. in relation to the Vicat point of the said thermoplastic elastomer containing polyamide blocks.

Abstract: A system for curing composite structures. A hollow bladder having opposing open ends is secured within a metal pressure vessel so as to define an annular space within the vessel surrounding the bladder. The open ends of the bladder are sealably attached to opposing entrances formed in the pressure vessel so that the bladder is sealed from communication with the vessel and is accessible through the opposing openings. An uncured composite part can be inserted into the bladder. Preheated and pressurized fluid is circulated through the annular space and thus around the bladder in order to cure the composite part. The composite part may also be encapsulated within a forming bladder member which is then removably inserted into the pressure bladder.

Abstract: A fusing member and a method for preparing such a fusing member are disclosed. The method has the steps of conversion coating a support member; applying a base cushion of thermally insulating silicone elastomer over the conversion coating; vulcanizing the base cushion; and baking the support member and the base cushion for at least 30 minutes at a temperature in excess of the temperature necessary to vulcanize the base cushion in less than 10 minutes.

Abstract: Liquid radiation-curable formulation, in particular for stereolithography, based on at least one compound that contains radically polymerizable groups, and at least one photoinitiator suitable for the polymerization, which formulation additionally contains a polyoxyalkylene-polysiloxane block copolymer that is selected from copolymers of the chemical formulae ##STR1## wherein: R.sup.1 is a hydrogen atom or a C.sub.1 -C.sub.8 alkyl group;R.sup.2 is a methyl or phenyl group;[T] is a polysiloxane group [PS] terminated as described in the specification in more detail;[PS] is the group of formula ##STR2## and [Alk] is an alkylene group of 3 to 10 carbon atoms, as well as novel block copolymers of formulae (I) and (II). The cured formulations have, inter alia, superior impact strength.

Abstract: A process for producing a composite part comprising:(i) putting short reinforcing fibers into a transfer mold;(ii) impregnation said short reinforcing fibers with a low viscosity resin;(iii) maintaining said short reinforcing fibers impregnated with by said resin in said transfer mold at a first temperature T.sub.1 known as the gelation temperature until a pasty preform is obtained whose viscosity is suitable for compression molding;(iv) removing said pasty preform from the mold;(v) placing said pasty preform in a compression mold brought to a second temperature T.sub.2, known as the compression temperature, wherein T.sub.2 >T.sub.1 ;(vi) compression molding said pasty preform; and(vii) polymerizing said pasty preform at at least a third temperature T.sub.3 wherein T.sub.3 .gtoreq.T.sub.2.

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: The present invention provides novel apparatus and a novel method for manufacturing an endless rubber track for large vehicles such as tractors or earth-moving machines. A plurality of sprocket-engaging core bar inserts are disposed in the inner portion or inner diameter of the endless rubber track to engage the power drive mechanism of the vehicle. Rubber tread is disposed on the outer portion or external diameter of the rubber track. Although the rubber track is made in segments, it is completely vulcanized, and does not have discontinuous, unvulcanized regions between vulcanized segments. Rubber track is formed using at least two different mold assemblies. In the first mold assembly, the interior and exterior portions of the rubber track are molded onto a green belt to form a first segment, and a central portion of the segment is vulcanized.

Abstract: An illuminated plastic lighting of alphanumeric symbols, such as letters, numbers or words, in soft feel buttons is provided, wherein a translucent rigid base portion is covered with a soft opaque plastic. The opaque plastic has the same thickness as a raised protrusion bearing the desired alphanumeric symbol. The opaque plastic coating is applied in a fluid condition to the top level of the alphanumeric symbol, for revealing the alphanumeric symbol through a recess in the opaque elastomeric coating material. A light source is placed at the bottom of the translucent base portion. The soft feel button is specially useful for making lighted buttons and more particularly, for soft feel buttons for automobile dashboards and the like.

Abstract: The present invention relates to a flexible tubular conduit with a jacket or tube made of crosslinked polyethylene, specially crosslinked polyethylene, and a method for manufacturing the conduit. A jacket or tube is made from polyethylene crosslinked by hydrolysis.

Abstract: Apparatus for molding an elongated cylindrical object includes an elongated cylindrical mold. First and second closure plates are positioned within the mold and an elongated tube is suspended between the closure plates within the mold. A sliding piston is mounted over the elongated tube. Molten plastic is introduced into the mold between the piston and one of the closure plates so as to cause the piston to slide along the tube within the mold toward the opposite closure plate. When the mold is filled, the piston engages the opposite closure plate, and further introduction of molten plastic is stopped. This process produces an elongated plastic body having the tube embedded therein.

Abstract: A fusing member and a method for preparing such a fusing member are disclosed. The method has the steps of conversion coating a support member; applying a base cushion of thermally insulating silicone elastomer over the conversion coating; vulcanizing the base cushion; and baking the support member and the base cushion at a temperature in excess of the temperature necessary to vulcanize the base cushion in less than 5 minutes.

Abstract: A process for upgrading low-quality wood including a softening stage, wherein one or more sections of low-quality wood are heated, in the presence of an aqueous medium and at a pressure which is at least the equilibrium pressure of the medium at the operating temperature, to a temperature in the range of from about 120.degree. C. to about 160.degree. C. and maintaining the temperature until the temperature difference between the center and the outer parts of the sections is less than about 20.degree. C., a dewatering stage and a curing stage.

Abstract: A method of manufacturing and mass-producing a seamless heat-resistant resinous tube with a uniform tube wall thickness and circumference, which includes the steps of coating the precursor solution of a tube material to the surface of a core at a thickness greater than the tube wall thickness; passing a metallic die having a wider inside diameter than the diameter of the core along the outside of the core by utilizing the resistant force of the precursor solution without restricting the metallic die or the core, thus forming a tube around the core; treating the tube around the core to give it strength as a tube; and separating the tube from the core.

Abstract: This invention is directed to a novel method and apparatus for casting stress-free thermosetting resin materials. A process for forming a thermosetting product which comprises: (a) pouring a thermosetting polymer, with initiator, and catalyst, into a cavity of a mold which has a polymer coating or film on the interior surface thereof; (b) permitting the polymer to cure to a point where the cured material is reasonably dimensionally stable; (c) removing the partially cured polymeric material from the mold and placing the material in an oven; and (d) fully curing the polymeric material in the oven.

Abstract: An improved liquid matrix system for producing fibre-reinforced plastic components is disclosed. The system comprises (i) a liquid diglycidyl ether of a halogenated bisphenol or a mixture of liquid polyglycidyl ether bisphenols at least one of which being a polyglycidyl ether halogenated bisphenol; and (ii) a curing agent that is a sterically hindered aromatic diamine containing two primary amino groups attached to the carbon atoms in the aromatic nucleus, said carbon atoms not adjacent to each other, and at least one C.sub.1 to C.sub.6 linear or branched alkyl or thioalkyl substituent; the improvement comprising adding to said system a curing accelerator composition containing a mixture of a boron halide and an imidazole unsubstituted or substituted with at least one C.sub.1 to C.sub.6 linear or branched alkyl or C.sub.6 to C.sub.10 aryl.

Abstract: A conductive polymer composition in which a particulate conductive filler is dispsered in a polymeric component which is a mixture of an essentially amorphous thermoplastic resin and a thermosetting resin. In preferred compositions, the amorphous thermoplastic resin and the thermosetting resin are substantially mutually soluble. In order to improve the thermal stability of the composition on exposure to successive thermal cycles, it is preferred that the composition be cured by heating the uncured mixture of amorphous thermoplastic resin, thermosetting resin, and particulate conductive filler at a rate of at least 15.degree. C./minute to the cure temperature.

Abstract: A trimodal method of curing dental composite restorative materials involves the use of visible light illumination for the initial curing of the composite resin and a combination of dry heat and vacuum for the complete cure of the composite restorative materials. More specifically, the method for preparing dental restorative materials includes the steps of forming a dental restoration from a composite resin of a type conventionally employed in the dental profession, in which the composite resin includes a photosensitizing system for initiating polymerization of the composite resin upon exposure to visible light, an initiator for initiating polymerization upon application of heat and at least one filler; exposing the thus prepared restoration to a source of visible light to at least partially cure said composite resin and then subjecting the thus prepared restoration to a combination of heat and vacuum to complete polymerization of said complete resin.

Abstract: A vulcanizing method including a cylindrical vulcanizing drum for winding and molding unvulcanized rubber belt materials thereover, the vulcanizing drum being removably and rotatably supported on a transfer mechanism. A pair of endless pressurizing bands are arranged to oppose each other with the vulcanizing drum between, the pressurizing bands arcuately surrounding and pressing the corresponding portions of the circumferential surface of the vulcanizing drum. While the circumferential surface of the vulcanizing drum is heated inside, and the respective pressurizing bands are opposingly pressed against the vulcanizing drum, the respective pressurizing bands are synchronously rotated so as to turn the vulcanizing drum and continuously vulcanize the unvulcanized rubber belt molding on the drum.

Abstract: A method is provided for making a rigid spacer, containing a silicone bound desiccant which is useful for a multi-pane sealed window. An infrared radiation curable silicone is used as a binder for a desiccant such as a zeolite which is injected in a continuous manner into a U-shaped or V-shaped semi-rigid spacer such as a steel channel.

Abstract: An isotropic, biaxially stretched polyimide film prepared by casting a solution of a polyamic acid precursor in an organic solvent containing a cyclization catalyst and dehydrating agent onto the surface of a support, imidizing the polyamic acid to give a continuous self-supporting gel film containing 5-50% by weight of solids, stretching the gel film in the machine direction (MD) at a ratio of 1.1-1.9, and stretching in the transverse direction (TD) with respect to the machine direction so as to maintain a TD/MD stretch ratio of from 0.9 to 1.3.

Abstract: A process for the preparation of an aromatic polyimide film includes the steps of casting a polyamide acid solution containing an imidization agent on a support in the form of a film, heating the filmy cast solution on the support at a temperature of 80.degree. to 200.degree. C. to obtain a self-supportable film; peeling the self-supportable film from the support; and further heating the film at a temperature of not lower than 300.degree. C. The polyamide acid solution includes a polyamide acid obtained by polymerization reaction of 3,4,3',4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine in a mixture of a polar organic solvent and a small amount of an imidization agent selected from imidazole, a substituted imidazole, benzimidazole, a substituted benzimidazole, isoquinoline, and a substituted pyridine.

Abstract: The starting end and the finishing end of a seam extruded onto a sheet of glass, for example a windshield of an automobile, are joined to complete an edge gasket. A separate supplementary mold receives part of the glass containing the ends of the seam, and a compatible polymerizable composition is poured into the mold to complete the gasket.

Abstract: The invention involves the use of about 1 to 4 %wt cured elastomer irregularly-shaped particles having a sieve size of about 0.7 mm +/-0.1 mm in uncured elastomer to suppress bubble formation without substantial loss of tensile strength, in calendered, cured elastomer products, such as, decorative or sealing sheet materials.

Abstract: This invention is a process for the production of a continuous running length of a thermosetting polymer by a continuously extruding a continuous running length of a sheath of a film forming fiber from a die to form a hollow object; b) continuously injecting the monomer of the thermosetting polymer into the hollow of the sheath at or immediately below the plane of the die opening; c) stretching the sheath containing the monomer; and d) polymerizing the monomer to make the continuous running length of fiber of thermosetting polymer.

Abstract: The present invention provides a process for producing molded articles of a polyimide precursor by a use of a usual extrusion technique, and physical properties of polyimide products prepared by the heat treatment of the molded articles of the polyimide precursor at 400.degree. C. are excellent. This process is characterized by drying a solid obtained by pouring a dilute solution of a polyimide precursor including an aromatic tetracarboxylic acid component and an aromatic diamine component 1 into a liquid in which the precursor is only poorly soluble to obtain a dry solid having a polyimide precursor concentration of 50-70% by weight, and then extruding this dry solid at 80.degree.-130.degree. C.

Abstract: The present invention relates to a method for molding an agglomerated preform of a fiber-reinforced composite material comprising a resin material as a matrix and reinforcing fibers dispersed therein, into a desired shape. In the molding method, the preform is heated from the interior thereof, whereby the temperature of the entire preform can be raised efficiently and uniformly. If an optional number of holes are formed in the agglomerated preform, rod-like heaters for heating or gas nozzles for the release of heated gas can be inserted into the preform easily through such holes, whereby uniform heating can be effected. Further, by incorporating an appropriate amount of a dielectric loss improver into the preform and thereafter subjecting the preform to high-frequency heating or microwave heating, the preform can be heated efficiently and uniformly in a short time.

Abstract: Method for forming a composite elastomer tire tread by applying a heat curable liquid elastomer mixture to a thin rubber sheet and curing the liquid mixture to form the composite tire tread. A tire retreaded with such a composite tire elastomer tread is also described.

Abstract: Hoses are often reinforced with fabric to improve their performance characteristics, such as burst strength. By utilizing the technique of this invention, hose which has a high level of burst strength can be manufactured without including continuous yarn reinforcement. This invention specifically reveals a process for manufacturing a hose which involves the steps of (1) extruding a rubber composition into the form of a tube, wherein the rubber composition contains (a) an EPDM alloy comprised of (i) standard EPDM rubber, (ii) an EPDM rubber having thermoplastic side chains grafted thereto, and (iii) dispersed thermoplastic wherein the thermoplastic is selected from the group consisting of nylons, polyesters, and polyphenylene oxides, (b) an EPDM rubber, (c) carbon black, (d) at least one curative, (e) zinc oxide, (f) a processing oil, and (g) stearic acid; (2) shaping the tube into the geometric form desired for the hose; and (3) curing the rubber composition at a temperature within the range of 130.degree. C.

Abstract: A method and apparatus for continuous casting of polymerizable thermosetting materials comprises mixing the materials with controlled amounts of two or more catalyst groups and passing said mixture through two or more series of heating stages. The initially gelled mixture which has not yet undergone excessive shrinkage is mechanically isolated from the ungelled mixture.

Abstract: A method of forming a body comprising resin material which can be crosslinked to form a thermally stable resin is carried out by the sequential steps of:(A) providing a body of resin which can be crosslinked to form a thermally stable resin;(B) selectively crosslinking said body to provide a first zone of substantially uncrosslinked resin; a zone of substantially crosslinked resin and a transition zone therebetween;(C) forming said first zone and transition zone; and(D) substantially crosslinking said first zone and transition zone.Step (C) can be carried out by introducing a first zone and associated transition zone into a mold cavity in effective contacting relationship with second zone of substantially uncrosslinked resin and associated transition zone and then step (D) can be carried out to thereby bond said first and second zone together. The present invention also relates to the products made by the method of this invention.

Abstract: A technique is described for the production of manufactured articles of composite material of large thickness, the matrix of which is composed of polymerizable resins, using electron beams. To achieve the polymerization of the matrix, it is proposed to induce the adhesion of the resin of a layer (1) of already polymerized material with the resin of a second layer (3) to be polymerized by irradiating the second layer and the zone of adhesion between the first and the second layer with electron beams (F) of appropriate energy. The method can also be used for the welding of a plurality of layers or portions of already polymerized material. This permits the polymerization of matrices of such a thickness as not to be penetrated in a single phase by electron beams of limited energy. The treatment by successive phases performs the polymerization of the resin matrix in a manner equivalent to a simultaneous treatment over the entire thickness.

Abstract: A method of manufacturing a open-back type working glove. A fiber-made glove is fitted on a dipping hand block, and same is dipped in a stock solution of a rubber latex composition. After the glove and hand block is removed from the stock solution, the solution deposited on the glove in an open-back fashion is heated so as to allow it to be semi-vulcanized. Then, the glove is removed from the dipping hand block and is immersed in water or warm water to allow the rubber coat in semi-vulcanized condition to swell and soften. Finally, the glove is fitted on a setting hand block having a thumb portion projecting considerably beyond the palm portion, with other four finger portions curved toward the palm portion, and the rubber coat is heated for final vulcanization.

Abstract: The specification is concerned with a process and apparatus for continuous manufacture of moisture curable silicone compositions.

Abstract: An extrusion method for obtaining a long phenolic resin pipe having excellent heat resistance by using an extruder having a screw, a cylinder, a die and a mandrel, the mandrel being inserted into a through-hole formed in the screw along the screw axis and protruding into the die along the screw axis, the die satisfying the following formulasR.sub.1 /R.sub.2 =0.25.about.1.0S.sub.1 /S.sub.2 =0.1.about.2.5where R.sub.1 is an outside diameter of the die flow path at the die outlet, S.sub.1 is a cross-sectional area of the die flow path at the die outlet, R.sub.2 is an outside diameter of the die flow path at the die inlet, and S.sub.2 is a cross-sectional area of the die flow path at the die inlet, and the inclination of the outer periphery of the die flow path portion from the die inlet to a starting point of the uniform flow path portion having the same cross section as the die outlet is not larger than 35.degree.

Abstract: A method for providing an inlay on a substrate includes providing a recess in the substrate, preheating the substrate to a temperature of approximately 150.degree. F., mixing an epoxy resin with an epoxy hardener, and placing the mixture into the recess so that the mixture hardens in the recess and the heat stored in the substrate reduces the viscosity of the mixture, to aid in the removal of bubbles.

Abstract: Process for manufacturing supported, solid, polymeric sheets from: (I) liquids containing components reactable to polymers; and (II) one or more indefinitely long, foraminous substrates. A more or less continuous sandwich is formed of such substrate(s) and, faced on each side of the substrates as a group, film extending beyond the lateral edges of the substrate(s), the plane of the sandwich deviating from vertical by not more than about 45 degrees.

Abstract: A force sensor component is formed including a dimensionally stable body of electrically conductive material, the body having a selected outer surface formed into a predetermined topography; the body including an electrically conductive material in an amount sufficient to render the body electrically conductive at least throughout the selected outer surface of the body; the predetermined topography of the outer surface of the body including a plurality of interconnecting ridges across the outer surface of the body.

Abstract: Disclosed is a method for curing flexible hose on a mandrel wherein the mandrel lubricant is a polyoxyalkylene based lubricant having a pH greater than 8.0; in the preferred embodiments, the lubricant contains an aminoalcohol; lubricant compositions are also disclosed.

Abstract: Surface characteristics of a molded article formed by a composition including a thermoplastic resin and a functionalized polyolefin resin or a composition incorporating the above composition and an inorganic filler or a rubbery substance incorporated therein can be improved without deteriorating such characteristics as rigidity, impact resistance, heat resistance, dimensional stability and moldability, by radiating an ultraviolet light not longer than 300 nm in wavelength to the molded article, the said functionalized polyolefin resin containing at least one member selected from the group consisting of carboxylic acid group-, carboxylic ester group- or acid anhydride group-containing monomers, epoxy group-containing monomers, hydroxyl group-containing monomers, amino group-containing monomers, alkenyl cyclic iminoether derivatives and polyfunctional monomers.

Abstract: A method and apparatus for continuous casting of polymerizable materials that shrink during polymerization includes rapidly heating a moving matrix substantially uniformly throughout its cross section by radio frequency energy to initiate polymerization and maintaining the matrix thereafter in substantial thermal isolation such that substantially adiabatic polymerization occurs.

Abstract: A method is disclosed for determining the distribution according to size of particles which make up a noncontinuous phase dispersed within a matrix which is not completely soluble in an aqueous solution. The method involves dissolving the matrix containing the particles in an essentially nonaqueous liquid causing the particles to be suspended. The suspension is then eluted through a separating medium which sorts the particles according to size. A detector monitors the effluent from the separating medium and creates a record of the data. This record is then compared to data obtained from known standards in order to estimate the size distribution in the sample.

Abstract: A method of making window glass with a gasket, which includes closing a mold having window glass placed therein to form an inner cavity for forming a resin gasket along the periphery of the window glass, injecting a thermoplastic resin material melted at a relatively low temperature, having a low viscosity and containing a crosslinking agent, into the inner cavity, solidifying it to form a resin gasket, and crosslinking and curing the resin gasket after removal from the mold.

Abstract: A solvent based plastics recycling process directly reduces large volumes of post consumer plastic waste materials by up to 500% by volume. Minimal sorting and no cleaning is required, and large percentages of contaminants are tolerated. The process yields a highly adhesive resin which cures to a hard wood or masonry type material. The reduced end product, an epoxy sludge, may be formed to provide a lumber or brick substitute. Large percentages of shredded paper and other waste materials, including metals, may be added to the plastic waste materials, if desired.

Abstract: A process and apparatus are disclosed for step-molding elongated work pieces, such as generator components. A heated press includes a cooling box attached thereto, separated by a thermal insulating gasket. As a first portion of the work piece is being heat cured, a second portion extending adjacent the heated press is placed within the cooling box to prevent its being cured from residual heat of the press. After the first portion has been cured, the second portion is sequentially placed within the heated press. In this manner, the entire elongated work piece is cured and inadvertent "bumps" in the cured work piece are prevented to form the component to its desired shape.

Abstract: Method of tempering workpieces of duroplastic plastic, in particular a piston for a motor vheicle brake, provides that the workpiece is heated after the pressing or molding according to a predetermined time-dependent temperature rise for several hours and after an initial heating phase a difference from the respective glass transition temperature of 5.degree. to 40.degree. C. is observed.

Abstract: An elevated temperature induced reduction of insulation resistance of a metal-polyethylene terephthalate film capacitor is eliminated by controlled cooling through a glass transition temperature of the polyethylene terephthalate film or by elevated temperature storing below the glass transition temperature.