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Polyetherimides and precursors thereof
Abstracts of patents UK and US patents are prepared by Drs F.R. Jones and R.J. Hand of the University of Sheffield, UK
UK PATENTS Pnlyetherimides and precursors thereof (General Electric Co, USA) GB 2 222 409 A (7 March 1990) The preparation of precursors and thermoplastic polyimides as matrices for composite materials is described. Resin covered alkali-resistant glass fibres (Nippon Electric Glass Co Ltd, Japan) GB 2 232 988A (2January 1991) Alkali-resistant, zirconia chopped glass fibre strands are covered with a thermoplastic coating during suspension polymerization (e.g., styrene-acrylonitrile copolymer). Autoclave resistance (i.e., fibre alkali resistance) and workability in the manufacturing process of cementitious composites are much improved. Armour materials (Ceramic Developments (Midlands) Ltd, UK) GB 2 233 074 A (2 January 1991) Protection from ballistic objects is provided by a glass ceramic bonded to an energy absorptive backing comprising high tensile fibres embedded in a polymer. The glass ceramic undergoes controlled crystallization to promote ballistic properties. (Summary only available.) Glass fibre high in tensile strength (Central Glass Company Ltd, Japan) GB 2 233 643 A (16 January 1991) A glass composition which can be fiberized conventionally at temperatures below 1500°C has a tensile strength in excess of 4.5 GPa. It is a calcium, magnesium aluminosilicate with one or more or the following oxides: Y203, La203, CeO2 and ZrO2. Carbonaceous fibres having coil-like •aments and methods of producing same (Central Glass Co Ltd, Japan) GB 2 233 971 A (23January 1991) A novel, coil-like carbon fibre (of 0.050.5 pan diameter) is obtained by vapour phase pyrolysis of an aliphatic hydrocarbon, preferably acetylene, in the presence of a transition metal catalyst. The coil has a diameter of 2-10 times the filament diameter with 0.51D to 51D turns/l~m. These are claimed to have application as short fibre reinforcements for composites giving novel adhesion. Other applications involve their electrical conduction. Modifications to these properties can be undertaken by creating a metal carbide surface layer (e.g., TiC) or by conversion into carbides. Improved pre-ceramic methylpolysilanes (Dow Coming Corp, USA) GB 2 233 980 A (23 January 1991) This improvement involves the reaction of methyl polysilanes with multiple unsaturated compounds to reduce the number of ternary
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COMPOSITES. JULY 1991
or highly reduced silicon atoms, by insertion reactions with alkenes and alkynes catalysed by phosphine complexes of the transition metals. For example, phenyl acetylene with (PhP)aRhCI or acetylene with (PhaP)4Pd give good yields of ceramic with good weight retention in air at 1200°C. The polymers are easier than methylpolysilanes to process into ceramic fibres.
A process for producing composite materials with silicon carbide fibre reinforcement and ceramic matrix (Societe Europeenne De Propulsion, France) GB 2 234 238 A (30January 1991) An intermediate coating designed to constitute the interface between fibres and matrix in a ceramic-matrix composite is achieved by removing the silica-rich surface from SiC fibres by treatment with strong acids (e.g., HF, HNO3 and mixtures of acids). After removal, a pyrolytic carbon coating of 0.3 p.m thickness is deposited by CVD. Composites prepared by CVD with SiC matrix have much improved properties. For example, 40% and 300% improvements in strength and failure strain respectively are reported.
Methylpolysilanes having controllable rheology and method of their preparation (Dow Coming Corp, USA) GB 2 234 254 A, GB 2 234 255 A (30 January 1991) The title polymers with controlled glass transition temperature from 0-200°C, are obtained by heating together alkoxydisilanes with three or four alkoxy groups and dialkoxysilanes. Catalysis by alkoxide ions, formed in situ from alkali metal alkyls such as butyl lithium, is described. The resulting polymers can be spun into pyrolysable precursors for SiC ceramic fibres.
US PATENTS COMPONENTS Three-layer cross.laminated film with foam core made by counter-rotating dies Herrington, F.J. (Mobil Oil Corporation, New York, NY, USA) US Pat 4 885 196 (5 December 1989) A high strength cross-laminated tubular thermoplastic film consists of an outer film material and at least one inner film material layer. Each layer is uniaxially orientated in a different direction with regard to the others. The layers are bonded together with a foamed adhesive material.
Graphite fibre reinforced rod construction Rumbaugh, J.T. and Chung, T. (Berkley Inc, Spirit Lake, IA, USA) US Pat 4 885 865 (12 December 1989) A hollow, tapered, circular cross-section fishing rod is claimed, the body of which consists of a laminar resinous matrix reinforced with continuous, contiguous, parallel graphite or silicon carbide fibres which are unidirectionally aligned along the direction of the rod. Phosphate bonded composite electrodes Lalancette, J.-M., Menard, H. and Potvin, E. (Universite de Sherbrooke, Sherbrooke, Canada) US Pat 4 886 591 (12 December 1989) A pressure moulded, rigid, high surface cathodic or anodic electrode is described which has low electrical resistance, good mechanical strength and is corrosion resistant. It consists of non-dissolving, electrically conducting metal particles of high specific surfaces and fractal structure bound with 2-15 wt % aluminium phosphate.
Alkyl poly(polysilyl)azane preceramic polymers (Dow Corning Corp, USA) GB 2 234 752 A (13 February 1991) These preceramic polymers are obtained by reacting a chlorine-containing polysilane with, or example, hexamethyl disilazane. They can be pyrolysed to high ceramic (SIC) yields. The polysilane can be varied according to GB 2 234 254/5 A to modify the glass transition temperature. The tolueneinsoluble components gave the highest ceramic yields.
Glass fibre reinforced fluoropolymeric circuit laminate Carroll, J.R., McGinnis, L.W., Miller, T.L. and Norris, M.B. (Rogers Corporation, Rogers, CT, USA) US Pat 4 886 699 (12 December 1989) A laminated circuit substrate for microwave applications consists of at least one layer of a fluoropolymer-impregnated woven glass cloth with at least one outer layer on both sides of a random, microglass-reinforced fluoropolymer. These outer layers provide smooth outer surfaces. The fiuoropolymer is selected from PTFE and the copolymer of tetrafluorethylene and perfluoroakyl ether.
Polysilane preceramic polymers (Dow Corning Corp, USA) GB 2 234 753 A (13 February 1991) The preparation of various chlorine- or bromine-containing polysilanes as preceramic polymers of high yield, are described. The use of rearrangement catalysts such as tetraalkyl phosphonium bromide is also discussed.
Heavy duty-high pressure pneumatic radial tyres Imai, I. and Inada, N. (Bridgestone Corporation, Tokyo, Japan) US Pat 4 887 655 (19 December 1989) The tyre has a carcass of an up-and-down type toroidal construction in which a plurality of parallel, organic fibre, cord plies are turned up round two bead cores. The cords are
UK PATENTS Pnlyetherimides and precursors thereof (General Electric Co, USA) GB 2 222 409 A (7 March 1990) The preparation of precursors and thermoplastic polyimides as matrices for composite materials is described. Resin covered alkali-resistant glass fibres (Nippon Electric Glass Co Ltd, Japan) GB 2 232 988A (2January 1991) Alkali-resistant, zirconia chopped glass fibre strands are covered with a thermoplastic coating during suspension polymerization (e.g., styrene-acrylonitrile copolymer). Autoclave resistance (i.e., fibre alkali resistance) and workability in the manufacturing process of cementitious composites are much improved. Armour materials (Ceramic Developments (Midlands) Ltd, UK) GB 2 233 074 A (2 January 1991) Protection from ballistic objects is provided by a glass ceramic bonded to an energy absorptive backing comprising high tensile fibres embedded in a polymer. The glass ceramic undergoes controlled crystallization to promote ballistic properties. (Summary only available.) Glass fibre high in tensile strength (Central Glass Company Ltd, Japan) GB 2 233 643 A (16 January 1991) A glass composition which can be fiberized conventionally at temperatures below 1500°C has a tensile strength in excess of 4.5 GPa. It is a calcium, magnesium aluminosilicate with one or more or the following oxides: Y203, La203, CeO2 and ZrO2. Carbonaceous fibres having coil-like •aments and methods of producing same (Central Glass Co Ltd, Japan) GB 2 233 971 A (23January 1991) A novel, coil-like carbon fibre (of 0.050.5 pan diameter) is obtained by vapour phase pyrolysis of an aliphatic hydrocarbon, preferably acetylene, in the presence of a transition metal catalyst. The coil has a diameter of 2-10 times the filament diameter with 0.51D to 51D turns/l~m. These are claimed to have application as short fibre reinforcements for composites giving novel adhesion. Other applications involve their electrical conduction. Modifications to these properties can be undertaken by creating a metal carbide surface layer (e.g., TiC) or by conversion into carbides. Improved pre-ceramic methylpolysilanes (Dow Coming Corp, USA) GB 2 233 980 A (23 January 1991) This improvement involves the reaction of methyl polysilanes with multiple unsaturated compounds to reduce the number of ternary
332
COMPOSITES. JULY 1991
or highly reduced silicon atoms, by insertion reactions with alkenes and alkynes catalysed by phosphine complexes of the transition metals. For example, phenyl acetylene with (PhP)aRhCI or acetylene with (PhaP)4Pd give good yields of ceramic with good weight retention in air at 1200°C. The polymers are easier than methylpolysilanes to process into ceramic fibres.
A process for producing composite materials with silicon carbide fibre reinforcement and ceramic matrix (Societe Europeenne De Propulsion, France) GB 2 234 238 A (30January 1991) An intermediate coating designed to constitute the interface between fibres and matrix in a ceramic-matrix composite is achieved by removing the silica-rich surface from SiC fibres by treatment with strong acids (e.g., HF, HNO3 and mixtures of acids). After removal, a pyrolytic carbon coating of 0.3 p.m thickness is deposited by CVD. Composites prepared by CVD with SiC matrix have much improved properties. For example, 40% and 300% improvements in strength and failure strain respectively are reported.
Methylpolysilanes having controllable rheology and method of their preparation (Dow Coming Corp, USA) GB 2 234 254 A, GB 2 234 255 A (30 January 1991) The title polymers with controlled glass transition temperature from 0-200°C, are obtained by heating together alkoxydisilanes with three or four alkoxy groups and dialkoxysilanes. Catalysis by alkoxide ions, formed in situ from alkali metal alkyls such as butyl lithium, is described. The resulting polymers can be spun into pyrolysable precursors for SiC ceramic fibres.
US PATENTS COMPONENTS Three-layer cross.laminated film with foam core made by counter-rotating dies Herrington, F.J. (Mobil Oil Corporation, New York, NY, USA) US Pat 4 885 196 (5 December 1989) A high strength cross-laminated tubular thermoplastic film consists of an outer film material and at least one inner film material layer. Each layer is uniaxially orientated in a different direction with regard to the others. The layers are bonded together with a foamed adhesive material.
Graphite fibre reinforced rod construction Rumbaugh, J.T. and Chung, T. (Berkley Inc, Spirit Lake, IA, USA) US Pat 4 885 865 (12 December 1989) A hollow, tapered, circular cross-section fishing rod is claimed, the body of which consists of a laminar resinous matrix reinforced with continuous, contiguous, parallel graphite or silicon carbide fibres which are unidirectionally aligned along the direction of the rod. Phosphate bonded composite electrodes Lalancette, J.-M., Menard, H. and Potvin, E. (Universite de Sherbrooke, Sherbrooke, Canada) US Pat 4 886 591 (12 December 1989) A pressure moulded, rigid, high surface cathodic or anodic electrode is described which has low electrical resistance, good mechanical strength and is corrosion resistant. It consists of non-dissolving, electrically conducting metal particles of high specific surfaces and fractal structure bound with 2-15 wt % aluminium phosphate.
Alkyl poly(polysilyl)azane preceramic polymers (Dow Corning Corp, USA) GB 2 234 752 A (13 February 1991) These preceramic polymers are obtained by reacting a chlorine-containing polysilane with, or example, hexamethyl disilazane. They can be pyrolysed to high ceramic (SIC) yields. The polysilane can be varied according to GB 2 234 254/5 A to modify the glass transition temperature. The tolueneinsoluble components gave the highest ceramic yields.
Glass fibre reinforced fluoropolymeric circuit laminate Carroll, J.R., McGinnis, L.W., Miller, T.L. and Norris, M.B. (Rogers Corporation, Rogers, CT, USA) US Pat 4 886 699 (12 December 1989) A laminated circuit substrate for microwave applications consists of at least one layer of a fluoropolymer-impregnated woven glass cloth with at least one outer layer on both sides of a random, microglass-reinforced fluoropolymer. These outer layers provide smooth outer surfaces. The fiuoropolymer is selected from PTFE and the copolymer of tetrafluorethylene and perfluoroakyl ether.
Polysilane preceramic polymers (Dow Corning Corp, USA) GB 2 234 753 A (13 February 1991) The preparation of various chlorine- or bromine-containing polysilanes as preceramic polymers of high yield, are described. The use of rearrangement catalysts such as tetraalkyl phosphonium bromide is also discussed.
Heavy duty-high pressure pneumatic radial tyres Imai, I. and Inada, N. (Bridgestone Corporation, Tokyo, Japan) US Pat 4 887 655 (19 December 1989) The tyre has a carcass of an up-and-down type toroidal construction in which a plurality of parallel, organic fibre, cord plies are turned up round two bead cores. The cords are