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Method for the manufacture of prepregs and their use
then drying the fibre strands at a temperature to discourage cross-linking. Reinforced plastic O'Connor, J. E., Geibel, J. F., and Beever, W. H. (Phillips Petroleum Company, Bartlesville, OK, USA) US Pat 4 792 481 (20 December 1988) The m e t h o d of preparing the fibrereinforced thermoplastic comprises preparing a slurry of a high molecular weight poly(arylene sulphide ketone) in particle form, with a certain Ca content, in a liquid. The reinforcement may be in the form of a strand, roving, or yarn, the fibres of which are stable at the melting point of the resin. The reinforcement is passed through the slurry to impregnate with the resin, heated at a temperature to evaporate the slurry liquid and soften the resin, subjected to a compressive force, and cooled.
PROCESSES Method for production of a hollow shaft of fiber-reinforced plastic Beckmann, H-D. (Volkswagen Aktiengesellschaft, Wolsburg, FRG) US Pat 4 774 043 (27 September 1988) The method of forming a hollow tube of 'dog-bone' shape is described. The tube is formed from braided fibre impregnated with a hardenable plastic and held in a fixed position during curing. RF plasma method of forming muitilayer reinforced composites Siemers, P. A. (General Electric Company, Schenectady, NY, USA) US Pat 4 775 547 (4 October 1988) A method of forming a high-strength fibrereinforced titanium base alloy composite is described. The titanium base alloy is in powder form of particle size >100~tm. It is radio frequency plasma spray deposited onto a receiving surface to form a first layer. A mat of filament reinforcement is then placed on top. A second layer of the titanium based powder is then RF plasma sprayed on top so that it is bonded to the first layer. The last two stages are then repeated at least one more time. The layers are then heated and isostatically pressed to form a composite of high density. Method of making extruded whiskerreinforced ceramic matrix composites Chen, S-L., Gadkaree, K. P. and Mach, J. F. (Coming Glass Works, Coming, NY, USA) US Pat 4 776 866 (11 October 1988) The method of making a whisker-reinforced ceramic matrix article comprises: compounding a solids component of 1-30 wt % inorganic whiskers and 70-79% of a powdered thermally crystallizable RO-AI203-SiO2 glass (R=Ca, Mg or Ba) containing an internal nucleating agent; extruding the batch to provide a green ceramic preform; heating this to a consolidation temperature in the range between the softening point temperature of the glass and a temperature not greater than 150°C above the liquidus temperature of the glass but below the deformation temperature of the preform, heating being at a rate sufficient to retain a
COMPOSITES. SEPTEMBER 1989
glassy phase consistuting at least 15 vol % of the solids component of the preform; cooling this consolidated preform to at least a temperature in the crystal nucleation range of the glass; heating the consolidated preform at a temperature in the crystal nucleation range for the glass and maintaining this temperature for a time sufficient to provide a nucleated preform; then heating the nucleated preform at a temperature in the crystallization range of the glass to crystallize the glass. Process for production of molded composites Irving, E. and Smith, T. J. (Ciba-Geigy Corporation, Ardsley, NY, USA) US Pat 4 776 992 (11 October 1988) The process for the production of a coated, reinforced epoxide or phenolic moulding comprises: applying to the surface of the mould a liquid comprising a photocurable residue and a residue having an epoxide or a phenolic hydroxyl group; exposing this layor to actinic radiation to solidify the surface but leaving the thermosettable residue; adding the reinforcement and an epoxide or phenolic resin; and heating to form a cured moulding. Process for shaping fiber composite materials Miller, A. K. (The Board of Trustees of the Leland Stanford Junior University, Stanford, CA, USA) US Pat 4 777 005 (11 October 1988) The apparatus for progressively deforming a piece of fibre-reinforced material contains seven pairs of opposed rollers through which the workpiece passes and which, in elevation, define a curved roll-line profile. The movement of the rollers is controlled selectively and individually. There is also a means of controlling the temperature of the workpiece within the rollers. When the workpiece passes between the rollers it is possible to retard its motion in the travel direction to induce tensile stresses to counteract the compressive stresses to which it is being subjected, the magnitude of the induced tensile stresses is such that the local stress on the compressively stressed fibres is reduced below the buckling stress; thus retaining the alignment of the fibres. Method for the manufacture of prepregs and their use Kleeberg, W., Hacker, H., Huber, J. and Wilhelm, D. (Siemens Aktiengesellschaft, Munich, FRG) US Pat 4 783 345 (8 November 1988) The solution for impregnation of reinforcing material comprises an aromatic and/or heterocyclic polyepoxy resin and an aromatic polyamine as hardener in an organic solvent. Process for making fibre reinforced products Cogswell, F. N., Cowen, G., Nield, E. and Turner, R. M. (Imperial Chemical Industries plc, London, UK) US Pat 4 783 349 (8 November 1988) Continuous fibrous filaments are coated prior to their introduction into a molten polymer to form a thermoformable fibrereinforced resin. The coating may be either a plasticizer which is capable of plasticizing the impregnating polymer; or a mixture of this plasticizer and <20 wt % of the plasticizer of a polymer miscible with the first plasticizer (which may or may not be the impregnating
polymer); or a coating resulting from coating the filaments with the above mixture and removing the plasticizer. Pressure reaction injection molding process for making molded bodies of thermosets optionally containing filler and/or reinforcing material Diethelm, H. and Dresen, W. (Ciba-Geigy Corporation, Ardsley, NY, USA) US Pat 4 784 814 (15 November 1988) An improvement to a pressure reaction injection moulding process allows compensating for the loss of volume due to shrinkage during the hardening phase. A reactive mixture of thermosetting pre-polymer material, hardening agent and a propertyenhancing filler, as needed, are introduced into the mould and heated to the hardening temperature. At this stage, fresh material may be introduced under pressure through an inlet in the upper half of the mould, the upper half being held at a temperature below the hardening temperature of the reactive mixture and the lower half being maintained at the hardening temperature. Composite molding process Chen, O. Y. (United Technologies Corporation, Hartford, CT, USA) US Pat 4 786 304 (22 November 1988) A method of making a hollow fibrereinforced glass article is described. Hightemperature-stable fibres are aligned in a mould cavity in the shape of the preform. A billet of high-temperature-stable glass material is heated above its flow point and poured into the mould cavity to surround the fibres, under pressure, and then the article is cooled. The inlets to the mould are inside the hollow preform and at the relative mid-point along the vertical axis of the article, thus minimizing preform distortion. Method of making delamination resistant composites Hertzberg, P. E. (The Boeing Company, Seattle, WA, USA) US Pat 4 786 343 (22 November 1988) A composite panel, made from a number of fibre plies in a resin matrix, is reinforced with a member also made from a number of fibre plies in a resin matrix, the two being bonded together with a high shear strength, high toughness, thermosetting adhesive resin layer, the resin of which is different from the matrix resins. Resistance to delamination is further enhanced by cross-ply stitching the plies of the composite panel. Process for treating reinforced polymer composite Amelio, W. J., Markovich, V., McCarthy, W. J., Moring, A. F., Moschak, P. A., and Strope, D. H. (International Business Machines Corporation, Armonk, NY, USA) US Pat 4 786 528 (22 November 1988) A method for treating a reinforced polymer to obtain a predictable amount of linear expansion comprises heating the composite at a temperature and for a time sufficient to obtain a moisture content below that for the RH level at which the composite is subsequently to be drilled, then subjecting the composite to a controlled environment at the required RI-I level for a time sufficient to increase the moisture content of the composite to that for the RH level.
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PROCESSES Method for production of a hollow shaft of fiber-reinforced plastic Beckmann, H-D. (Volkswagen Aktiengesellschaft, Wolsburg, FRG) US Pat 4 774 043 (27 September 1988) The method of forming a hollow tube of 'dog-bone' shape is described. The tube is formed from braided fibre impregnated with a hardenable plastic and held in a fixed position during curing. RF plasma method of forming muitilayer reinforced composites Siemers, P. A. (General Electric Company, Schenectady, NY, USA) US Pat 4 775 547 (4 October 1988) A method of forming a high-strength fibrereinforced titanium base alloy composite is described. The titanium base alloy is in powder form of particle size >100~tm. It is radio frequency plasma spray deposited onto a receiving surface to form a first layer. A mat of filament reinforcement is then placed on top. A second layer of the titanium based powder is then RF plasma sprayed on top so that it is bonded to the first layer. The last two stages are then repeated at least one more time. The layers are then heated and isostatically pressed to form a composite of high density. Method of making extruded whiskerreinforced ceramic matrix composites Chen, S-L., Gadkaree, K. P. and Mach, J. F. (Coming Glass Works, Coming, NY, USA) US Pat 4 776 866 (11 October 1988) The method of making a whisker-reinforced ceramic matrix article comprises: compounding a solids component of 1-30 wt % inorganic whiskers and 70-79% of a powdered thermally crystallizable RO-AI203-SiO2 glass (R=Ca, Mg or Ba) containing an internal nucleating agent; extruding the batch to provide a green ceramic preform; heating this to a consolidation temperature in the range between the softening point temperature of the glass and a temperature not greater than 150°C above the liquidus temperature of the glass but below the deformation temperature of the preform, heating being at a rate sufficient to retain a
COMPOSITES. SEPTEMBER 1989
glassy phase consistuting at least 15 vol % of the solids component of the preform; cooling this consolidated preform to at least a temperature in the crystal nucleation range of the glass; heating the consolidated preform at a temperature in the crystal nucleation range for the glass and maintaining this temperature for a time sufficient to provide a nucleated preform; then heating the nucleated preform at a temperature in the crystallization range of the glass to crystallize the glass. Process for production of molded composites Irving, E. and Smith, T. J. (Ciba-Geigy Corporation, Ardsley, NY, USA) US Pat 4 776 992 (11 October 1988) The process for the production of a coated, reinforced epoxide or phenolic moulding comprises: applying to the surface of the mould a liquid comprising a photocurable residue and a residue having an epoxide or a phenolic hydroxyl group; exposing this layor to actinic radiation to solidify the surface but leaving the thermosettable residue; adding the reinforcement and an epoxide or phenolic resin; and heating to form a cured moulding. Process for shaping fiber composite materials Miller, A. K. (The Board of Trustees of the Leland Stanford Junior University, Stanford, CA, USA) US Pat 4 777 005 (11 October 1988) The apparatus for progressively deforming a piece of fibre-reinforced material contains seven pairs of opposed rollers through which the workpiece passes and which, in elevation, define a curved roll-line profile. The movement of the rollers is controlled selectively and individually. There is also a means of controlling the temperature of the workpiece within the rollers. When the workpiece passes between the rollers it is possible to retard its motion in the travel direction to induce tensile stresses to counteract the compressive stresses to which it is being subjected, the magnitude of the induced tensile stresses is such that the local stress on the compressively stressed fibres is reduced below the buckling stress; thus retaining the alignment of the fibres. Method for the manufacture of prepregs and their use Kleeberg, W., Hacker, H., Huber, J. and Wilhelm, D. (Siemens Aktiengesellschaft, Munich, FRG) US Pat 4 783 345 (8 November 1988) The solution for impregnation of reinforcing material comprises an aromatic and/or heterocyclic polyepoxy resin and an aromatic polyamine as hardener in an organic solvent. Process for making fibre reinforced products Cogswell, F. N., Cowen, G., Nield, E. and Turner, R. M. (Imperial Chemical Industries plc, London, UK) US Pat 4 783 349 (8 November 1988) Continuous fibrous filaments are coated prior to their introduction into a molten polymer to form a thermoformable fibrereinforced resin. The coating may be either a plasticizer which is capable of plasticizing the impregnating polymer; or a mixture of this plasticizer and <20 wt % of the plasticizer of a polymer miscible with the first plasticizer (which may or may not be the impregnating
polymer); or a coating resulting from coating the filaments with the above mixture and removing the plasticizer. Pressure reaction injection molding process for making molded bodies of thermosets optionally containing filler and/or reinforcing material Diethelm, H. and Dresen, W. (Ciba-Geigy Corporation, Ardsley, NY, USA) US Pat 4 784 814 (15 November 1988) An improvement to a pressure reaction injection moulding process allows compensating for the loss of volume due to shrinkage during the hardening phase. A reactive mixture of thermosetting pre-polymer material, hardening agent and a propertyenhancing filler, as needed, are introduced into the mould and heated to the hardening temperature. At this stage, fresh material may be introduced under pressure through an inlet in the upper half of the mould, the upper half being held at a temperature below the hardening temperature of the reactive mixture and the lower half being maintained at the hardening temperature. Composite molding process Chen, O. Y. (United Technologies Corporation, Hartford, CT, USA) US Pat 4 786 304 (22 November 1988) A method of making a hollow fibrereinforced glass article is described. Hightemperature-stable fibres are aligned in a mould cavity in the shape of the preform. A billet of high-temperature-stable glass material is heated above its flow point and poured into the mould cavity to surround the fibres, under pressure, and then the article is cooled. The inlets to the mould are inside the hollow preform and at the relative mid-point along the vertical axis of the article, thus minimizing preform distortion. Method of making delamination resistant composites Hertzberg, P. E. (The Boeing Company, Seattle, WA, USA) US Pat 4 786 343 (22 November 1988) A composite panel, made from a number of fibre plies in a resin matrix, is reinforced with a member also made from a number of fibre plies in a resin matrix, the two being bonded together with a high shear strength, high toughness, thermosetting adhesive resin layer, the resin of which is different from the matrix resins. Resistance to delamination is further enhanced by cross-ply stitching the plies of the composite panel. Process for treating reinforced polymer composite Amelio, W. J., Markovich, V., McCarthy, W. J., Moring, A. F., Moschak, P. A., and Strope, D. H. (International Business Machines Corporation, Armonk, NY, USA) US Pat 4 786 528 (22 November 1988) A method for treating a reinforced polymer to obtain a predictable amount of linear expansion comprises heating the composite at a temperature and for a time sufficient to obtain a moisture content below that for the RH level at which the composite is subsequently to be drilled, then subjecting the composite to a controlled environment at the required RI-I level for a time sufficient to increase the moisture content of the composite to that for the RH level.
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