The Boeing Company

Environmental Protection Polymers, Inc.

Trw Limited

Other

The United States of America As Represented by the Administrator of the

Hyman R Lubowitz

Clyde H Sheppard

Ronald R Stephenson

Samuel L Unger

Rodney W Telles

Thomas Karl Tsotsis

Larry P Torre

William G Gaskill

Water-entrained compositions comprising colloidal or suspensoidal solutions comprising polyimide pre-polymers/oligomers are described. These compositions are obtained in water by initial dispersion of the resin constituents in water to from colloids or suspensoids. The water-entrained polyimide compositions can be applied to numerous surfaces or more beneficially used for composite fabrication. The coated surfaces or polyimide-pre-polymer impregnated reinforcing materials are subsequently cured and are ideal for providing thermal protection.

Water-entrained-polyimide chemical compositions for use in high-performance composite fabrication

A process for synthesizing formulations for polyimides suitable for use in high-temperature composites in which all reactions other than chain-extension have already taken place prior to making a composite is described, wherein the resulting oligomers comprise a backbone and at least one difunctional endcap. The resulting resin systems have only the single step of endcap-to-endcap reactions during composite processing. Prior to the initiation temperature of these endcap-to-endcap reactions, the resins are stable affording the composite manufacturer a very large processing window.

Single-step-processable polyimides

High performance polyester sulfone oligomers are prepared for aerospace applications by condensing mono- or difunctional crosslinkable end caps (i.e. unsaturated hydrocarbons having one or two crosslinking sites) with dicarboxylic acid halides and dialcohols (i.e. diols). Multidimensional oligomers have an aromatic hub from which the polyester chains radiate. Blends of the linear and multidimensional oligomers can be made using compatible, non-crosslinking polymers. Prepregs and composites are formed from the oligomers or blends.

Polyester oligomer

The physical properties of high performance composites can be tailored by using blends to make the composites. The resulting composites are relatively easy to make and have long-term, high performance capabilities even in harsh service conditions. The blends of the present invention include at least one oligomer having an aromatic, aliphatic, or mixed aromatic and aliphatic backbone from one chemical family and an unsaturated hydrocarbon end cap and at least one polymer from a different chemical family. Upon curing, the oligomer in the blend addition polymerize to form composites possessing advanced properties with respect to those exhibited by the pure oligomer or the pure polymer. Coreactive oligomer blends can be used instead of a pure oligomer to form composites that include addition polymers, block copolymers, and the compatible polymer, thereby further achieving a tailoring of properties in the cured composite. The blends can be prepregged and cured to form composites.

Composites from blends of advanced oligomers

The morphology of multidimensional, thermally stable oligomers is combined with the inclusion of charge carrier linkages within the polymer arms to produce thermally stable advanced composites from cured oligomers that are conductive or semiconductive if suitably doped.

Conductive, thermally stable oligomers

Thermomechanical and thermo-oxidative stabilities in resin composites across the range of aerospace 'engineering thermoplastic' resins are improved by forming four crosslinks at each addition polymerization site in the backbone of the resin using crosslinking functionalities of the general formula: ##STR1## wherein Z= ##STR2## .beta.=the residue an organic radical selected from the group consisting of: ##STR3## R.sub.R =a divalent organic radical; X=halogen; Me=methyl T=allyl or methallyl. G=--CH.sub.2 --,--S--, --CO--, --SO--, --O--, --CHR.sub.3 --, or --C(R.sub.3).sub.2 --; i=1 or 2; R.sub.3 =hydrogen, lower alkyl, lower alkoxy, aryl, or aryloxy; and .theta.=--C.tbd.N, --O--C.tbd.N, --S--C.tbd.N, or --CR.sub.3 .dbd.C(R.sub.3).sub.2 --

Oligomers with multiple chemically functional end caps

The morphology of multidimensional oligomers is combined with the inclusion of charge carrier linkages within the oligomer arms to produce oligomers that are useful for preparing conductive or semiconductive composites, if suitably doped. The Schiff base linkages are prepared by the condensation of aldehydes and amines. The oligomers can be blended, and either the oligomers or their blends can be prepregged.

Conductive, multidimensional oligomers and blends

Phenylethynyl capped imides

Crosslinkable poly(arylene sulfide) oligomers are prepared by reaction of a dihaloaromatic compound, a sulfur compound that is reactive with halo organic compounds to form thioethers, and an end cap monomer corresponding to the formula:

Reactive polyarylene sulfide oligomers

The yield of fully substituted, multidimensional aromatic hubs in the condensation of hydroxyl and acid halide functionalities is improved by adding a thallium catalyst, such as thallium ethoxide (Tl-OC.sub.2 H.sub.5), in the solvent.

Multidimensional polyesters

Method for making multidimensional polyester oligomers

Polyimide oligomers include (1) linear, mono-functional crosslinking oligomers prepared by condensing a monoanhydride end cap with a diamine that includes alternating ether and 'sulfone' (--SO.sub.2 --, --S--, --CO--, --(CF.sub.3).sub.2 C--, or --(CH.sub.3).sub.2 C--) linkages connecting alternating aromatic radicals and with a dianhydride (or dianhydride mixture), particularly the unsaturated, aliphatic dianhydride commonly known as MCTC; (2) linear, mono- or difunctional crosslinking oligomers prepared by condensing an amine end cap with a diamine and a dianhydride; and (3) multidimensional, crosslinking oligomers having an aromatic hub and at least three radiating arms connected to the hub, each arm including a crosslinking end cap at its distal end and at least one imide linkage. Blends, prepregs, and composites can be prepared from the oligomers. The blends are prepared by mixing miscile solutions of the oligomer and a noncrosslinking polyimide polymer to forma lacquer which is then swept out into a fabric to form a polyimide blend prepreg. Multidimensional oligomers can be prepared using etheranhydride intermediates or etheramine intermediates formed by reacting a suitable hub with nitrophthalic anhydride or aminophenol.

Method for making a polyimide blend

High performance polyester sulfone oligomers are prepared for aerospace applications by condensing mono- or difunctional crosslinkable end caps (i.e. unsaturated hydrocarbons having one or two crosslinking sites) with dicarboxylic acid halides and dialcobols (i.e. diols). Multidimensional oligomers have an aromatic hub from which the polyester chains radiate. Blends of the linear and multidimensional oligomers can be made using compatible, non-crosslinking polymers. Prepregs and composites are formed from the oligomers or blends.

Polyester sulfone oligomers and blends

Low molecular weight resins that usually are aliphatic and that include crosslinking thermal functional groups are useful as liquid molding compounds for reaction injection molding or resin transfer molding. The compounds eliminate the need to handle solvents when preparing thermoset composites.

Growing community of inventors

Rolling Hills Estates, CA, United States of America

Hyman R Lubowitz