Abstract: A resin reservoir particularly adapted for use with a resin transfer molding process. This reservoir comprises a pressure yielding porous sponge containing about two to about ten times the sponge's weight in resin. The reservoir is used in a resin transfer molding process. The process comprises applying pressure to a pressure yielding porous sponge containing resin to transfer the resin to a porous article precursor. The resin reservoir facilitates resin transfer molding by providing a resin reservoir that can ensure the desired impregnation of a porous preform such as a dry fiber composite precursor.

Abstract: This invention is directed to a thermal barrier layer particularly adapted for insulating a solid flowable particulate polymeric pressure transfer medium from elevated temperatures during high temperature molding. A method useful with the thermal barrier comprises transferring pressure from a pressure means via the thermal insulation layer to an article and exposing the article to temperatures of about 316.degree. C. to about 1371.degree. C. An exemplary thermal barrier comprises at least two flexible layers of beads having a thermal insulation of less than about 2 k.

Abstract: A method for molding high temperature composites that transmits more uniform pressures to the surface of the composites. A compliant glass, glass-ceramic, or ceramic layer is caused to apply pressure to a composite precursor and heat is applied to the composite precursor to form a composite.

Abstract: A method of making a high strength carbon-carbon utilizing a solid flowable particulate polymer as a pressurizing medium. A resin impregnated carbon fiber reinforced prepreg is disposed in a pressure vessel and the vessel is substantially filled with a solid flowable particulate polymer. The prepreg is exposed to sufficient temperatures and pressures to cure the prepreg to form a carbon-carbon precursor which is subsequently exposed to temperature and pressures sufficient to post-cure the carbon-carbon precursor. The post-cured carbon-carbon precursor is exposed to temperatures and pressures sufficient to carbonize said post-cured carbon-carbon precursor to form a carbon-carbon composite.

Abstract: This invention is directed to a thermal barrier layer particularly adapted for insulating a solid flowable particulate polymeric pressure transfer medium from elevated temperatures during high temperature molding. A method useful with the thermal barrier comprises transferring pressure from a pressure means via the thermal insulation layer to an article and exposing the article to temperatures of about 316.degree. C. to about 1371.degree. C. An exemplary thermal barrier comprises at least two flexible layers of beads having a thermal insulation of less than about 2 k.

Abstract: A method of molding using breather layers particularly adapted for use for removing fluids from articles during molding, that retain fluid paths at high pressures. Polymer containing articles are molded using a breather layer that is substantially capable of maintaining a fluid path under pressures up to about 20.7 MPa. The method includes transferring pressure via a gas impervious layer to the article. The breather layer is disposed between the article and the gas impervious layer and provides a fluid path for removing fluids from the article. An exemplary breather layer includes at least two flexible layers of beads that are dimensionally stable at pressures up to about 20.7 MPa. These breather layers facilitate high pressure molding by maintaining a sufficient fluid path size so that volatiles can be easily vented. This results in stronger, denser composite articles.

Abstract: An article is molded by contacting it with a solid polymer medium, such as an especially low strength unfilled silicone rubber which is solid and able to flow readily. Thermal expansion of the medium or mechanical force is used to create molding pressure and thereby provides a substantially uniform pressure on the article precursor. Various temperature and pressure cycles can be attained; constant high pressures can be maintained on the article precursor during cooldown, optionally aided by flowing of medium to and from a vessel in which the article precursor is being molded. The method is particularly adapted to molding filler or fiber reinforced thermosetting polymer composite articles.

Abstract: A continuous process method of molding composites. The method includes substantially filling a pressure chamber with a solid flowable polymer. The pressure chamber has a series of subchambers separated by a series of spaced apart baffles, but connected through baffle openings. A tube connects at least two subchambers, a transferring subchamber and a receiving subchamber. The polymer is displaced through the tube producing a polymer flow in the chamber through the baffle openings from the receiving subchamber to the transferring subchamber causing the receiving subchamber to have a higher pressure than the transferring subchamber. A composite precursor is passed through the pressure chamber by entering the precursor through the low pressure transferring subchamber wherein the composite precursor is exposed to pressure caused by the solid flowable polymer in order to cure the composite.

Abstract: Breather layers particularly adapted for use for removing fluids from articles during molding, that retain fluid paths at high pressures. Polymer containing articles are molded using a breather layer that is substantially capable of maintaining a fluid path under pressures up to about 20.7 MPa. The method comprises transferring pressure via a gas impervious layer to the article. The breather layer is disposed between the article and the gas impervious layer and provides a fluid path for removing fluids from the article. An exemplary breather layer comprises at least two flexible layers of beads that are dimensionally stable at pressures up to about 20.7 MPa. These breather layers facilitate high pressure molding by maintaining a sufficient fluid path size so that volatiles can be easily vented. This results in stronger, denser composite articles.

Abstract: A method of molding a polymeric containing article by exposing the article to ultraviolet radiation and a substantially uniform pressure. The method includes placing the precursor article within a pressure vessel and substantially filling the vessel with a solid, flowable, polymer medium that is substantially ultraviolet transparent under pressure. The polymer medium is pressurized so as to produce a substantially, uniform predetermined pressure on the surface of the article and the article is exposed to ultraviolet radiation that passes through the polymer medium to cure the article. Alternatively, the polymeric article may be passed through the medium containing vessel during exposure to ultraviolet radiation and a substantially uniform pressure.

Abstract: A method of recovering a solid flowable polymer medium that is capable of being used as a pressurizing medium for high temperature molding from contaminants. A polymer mixture containing contaminants that was a solid flowable polymer medium prior to exposure to temperatures in excess of about 316.degree. C. during its use as a pressurizing medium is disposed in a solution. The solution has a specific gravity greater than the solid flowable polymer medium. The solid flowable polymer medium is separated from the surface of the solution and contamination settles to the bottom.

Abstract: Barriers used for separating silicone pressurizing medium from articles during curing, thereby protecting the article from silicone contamination. A composite precursor is substantially encapsulated by a barrier coating that is capable of substantially separating the composite precursor from silicone polymers at elevated temperatures during curing. The barrier coating is also capable of being chemically removed from the composite precursor subsequent to its cure without substantially damaging the composite. Composites are molded by protecting a composite precursor from a silicone pressurizing medium during curing utilizing a barrier coating. The method comprises encapsulating a composite precursor with a coating that is substantially capable of separating the composite precursor from silicone polymers at elevated temperatures. The coating is also capable of being chemically removed from the composite without damaging the composite.

Abstract: A solid flowable polymeric material useful as a pressurizing medium that is ultraviolet detectable and is particularly adapted for use in a molding process. The polymeric material comprises a substantially uniform mixture of a solid, flowable, particulate silicone having a nominal flow rate of at least 0.6 gram per second through a 1.1 cm diameter pipe 7.6 cm long under applied pressure of 10.34 MPa at room temperature and an ultraviolet detectable compound. The polymeric material is especially useful for molding composites. A composite is disposed with a pressure vessel which is substantially filled with the above mixture. The silicone is caused to produce a substantially uniform, predetermined medium pressure on the surface of said composite prepreg. The composite prepreg is cured to form a composite which is removed from the pressure vessel and exposed to ultraviolet light.

Abstract: A flowable particulate polymer-metal mixture that is thermally conductive and is particularly adapted for use as a pressurizing medium in a high pressure elevated temperature molding process. The material comprises a substantially uniform mixture of about 20% to about 90% solid flowable, particulate silicone rubber having a nominal flow rate of at least 0.6 gram/second through a 1.1 cm diameter pipe 7.6 cm long under applied pressure of 10.34 MPa at room temperature. The material also comprises about 10% to about 80% thermally conductive particulate metal that has a melting point less than the molding temperature and is substantially chemically compatible with said silicone rubber. The pressurizing medium is used to mold article precursors into articles by placing an article precursor within a pressure vessel and substantially filling the vessel with a pressurizing mixture.

Abstract: A method of molding an article utilizing two types of solid flowable particulate polymer pressurizing media wherein one medium is protected from thermal degradation by a second medium. The method comprises disposing an article precursor within a pressure vessel and disposing a first solid flowable polymer medium that is substantially thermally stable at temperatures in excess of about 316.degree. C. so that it is capable of transferring a substantially uniform, predetermined medium pressure to the surface of the article precursor. A second solid flowable polymer medium is disposed so that it is capable of transferring a substantially uniform, predetermined medium pressure to the first polymer medium. The second medium is caused to produce a substantially uniform medium pressure so that said pressure is transferred to the surface of the article precursor and the article precursor is exposed to temperatures in excess of about 316.degree. C.

Abstract: A method for molding composite prepregs using high temperature substantially cured thermosetting resins that reduces fiber damage. Fiber plies are impregnated with solutions of high temperature substantially cured thermosetting resins and the plies are stacked to form a prepreg. A solid flowable particulate silicone rubber is caused to apply pressure to the prepreg to form a composite.This invention makes a significant advance in the field of molding high temperature resin composites by providing methods of molding that reduce fiber damage, shorten molding time and result in denser parts.

Abstract: A method particularly adapted for making a complex shaped composite component that has reduced bridging defects. The method comprises disposing a composite prepreg on to a substantially flat tool. The composite prepreg has a substantially flat section and at least one prepreg member extending from and substantially perpendicular to said flat section. A layer, at least about 125% of said composite prepreg height, of a said flowable particulate silicone rubber is disposed in substantially complete contact with the composite prepreg surface. The particulate silicone rubber has a flow rate of at least 0.6 gram/second through a 1.1 cm diameter pipe 7.6 cm long under applied pressure of 10.34 MPa at room temperature. The layer of solid flowable rubber is covered with a bag to effect a gas tight seal. The bag is exposed to pressures which are transferred to said prepreg by said solid flowable polymer. The composite prepreg is exposed to temperatures to form a composite component.

Abstract: A flowable particulate polymer-metal mixture that is thermally conductive and is particularly adapted for use as a pressurizing medium in a high pressure elevated temperature molding process. The material comprises a substantially uniform mixture of about 20% to about 90% solid flowable, particulate silicone rubber having a nominal flow rate of at least 0.6 gram/second through a 1.1 cm diameter pipe 7.6 cm long under applied pressure of 10.34 MPa at room temperature. The material also comprises about 10% to about 80% thermally conductive particulate metal that has a melting point less than the molding temperature and is substantially chemically compatible with said silicone rubber. The pressurizing medium is used to mold article precursors into articles by placing an article precursor within a pressure vessel and substantially filling the vessel with a pressurizing mixture.

Abstract: A method of fabricating a fiber reinforced resin composite article having tubular structures that has improved density and fewer voids. The method comprises laying up a prepreg that has at least two tubular structures and disposing a thermally conductive metallic support structure within and in contact with the tubular structures. The prepreg is disposed within and in substantially complete contact with a tool which has at least one hole. An expandable bag having at least one opening in communication with a tube is inserted within each tubular structure thereby forming a void space between the bag and the tubular structure. The void space is substantially filled with a solid flowable particulate silicone rubber that contacts the prepreg and the tube is sealed to edge of hole in the tool. The solid flowable rubber is caused to transfer a substantially uniform predetermined pressure to the surface of the prepreg by pressurizing the expandable bag.

Abstract: An ablative thermal barrier on the interior surface of a cylindrical combustor is made by first molding a silicone rubber strip with shaped edges. The strip is then laid inside the combustor so that it runs circumferentially either as a helix or as a series of circles. The adjacent turns are spaced apart by a gap into which is interposed a thermosetting polymer material. The rubber is then pressed radially outward so that the adjacent turns are caused to press laterally against each other. The thermosetting material is then cured while in its resultant compressed condition, to make the material into a circular or helical rib which better retains the rubber in place during use.