Abstract: A method for fabricating composite structures wherein a single mold is used to preform a foam core between fiber reinforcement plies that are subsequently subjected to resin transfer molding to form an integrated foam core composite structure having the formed foam core mechanically interlocked to the composite skins. Fiber reinforcement plies are layed up on contoured molding surfaces of dies to define a core cavity with the mold closed. Foam is injected into the core cavity, concomitantly penetrating the fiber reinforcement plies, and allowed to cure to form the foam core. Heat and pressure generated during foam cure compresses the fiber reinforcement plies to provide debulking therefor. A resin binder is injected into the mold plenum to impregnate the layed-up fiber reinforcement plies, and the formed foam core/resin-impregnated layed-up fiber reinforcement plies are subsequently cured to form the integrated foam core composite structure.

Abstract: Reaction injection molded polyurea elastomers are disclosed that are derived from the reaction of (1) an aromatic polyisocyanate; (2) primary or secondary amine terminated polyethers; and (3) an aromatic amine extender combination comprising (a) an aromatic diamine having at least one of the positions ortho to each amine group substituted by a lower alkyl group and (b) a polymethylene polyphenylamine.The use of the polymethylene polyphenylamine component allows for the retention of the good physical properties of the prior art polyureas while at the same time effecting a cost reduction in the preparation of this useful class of polymers.

Abstract: The use of certain prepolymers of 4,4'-methylenebis(phenyl isocyanate), in place of the latter diisocyanate itself in the preparation of polyurethane-polyureas using aromatic diamine extenders, has a number of advantages particularly when the compositions are prepared by reaction injection molding techniques using two streams of reactants. The principal advantages are (i) a useful increase in gel time and (ii) a ratio of amounts of the two reactant streams which more nearly approaches 1:1.This latter factor not only improves the efficiency of mixing of the components in the mixing head but, together with the longer gel time, significantly increases the output of mixed reactants per unit of time. The prepolymers of 4,4'-methylenebis(phenyl isocyanate) employed to achieve the above results are those derived from polyoxyethylene polyoxypropylene polyether diols and triols (MW=1000-10,000), polytetramethylene glycols (MW=600-5,000) and polyester diols and triols (MW=500-8,000).

Abstract: Elastomeric polyurethane-polyurea polymers are disclosed that are derived from the reaction of organic polyisocyanates with A. primary hydroxyl polyols having a functionality of 2 to 4 and a molecular weight from 1500 to 12000, and B. extender mixtures comprised of 1. an aromatic diamine wherein at least one of the positions ortho to each amine group is substituted by a lower alkyl group, and 2. a lower molecular weight diol, provided that the aromatic diamine comprises from 5 to 45 percent by weight of the extender mixture and the balance comprises the diol.The polymers find particular utility in the preparation of reaction injection molded parts, particularly, automotive parts because of their excellent flexural modulus, tensile, and tear properties.

Abstract: Novel solid polyisocyanurate polymers are disclosed which comprise the reaction product of an organic polyisocyanate, a trimerization catalyst and a polyol combination comprising from about 0.025 to about 0.15 equivalent and about 0.05 to about 0.25 equivalent, per equivalent of polyisocyanate, respectively of a polypropyleneoxy triol having an equivalent weight of from about 750 to about 1500 and ethylene glycol.Although containing a higher proportion of polyurethane linkages than those polyisocyanurates containing the polypropyleneoxy triol alone, the polymers of the invention are characterized by superior high temperature resistance and are particularly useful in the preparation of high modulus molded parts using reaction injection molding (RIM) techniques.

Abstract: Novel solid polyisocyanurate polymers are disclosed which comprises the reaction product of an organic polyisocyanate, a trimerization catalyst and a polyol combination comprising from about 0.025 to about 0.15 equivalent and about 0.05 to about 0.25 equivalent, per equivalent of polyisocyanate, respectively of an ethylene oxide capped polypropyleneoxy glycol having an equivalent weight of from about 750 to about 1500 and either 1,4-butanediol or diethylene glycol.Although containing a higher proportion of polyurethane linkages than those polyisocyanurates containing the polypropyleneoxy glycol alone, the polymers of the invention are characterized by superior high temperature resistance and are particularly useful in the preparation of high modulus molded parts using reaction injection molding (RIM) techniques.

Abstract: A novel liquid isocyanate prepolymer composition is disclosed. The prepolymer is obtained by reacting a polymethylene polyphenylisocyanate containing from about 65 to about 85 percent by weight of methylenebis(phenylisocyanate) the remainder of said polymethylene polyphenylisocyanates having a functionality greater than 2, with from about 0.0185 to about 0.15 equivalent per equivalent of said polyphenylisocyanate of a polyoxyethyleneglycol having an average molecular weight of from about 200 to about 600. The liquid isocyanates so produced are characterized as storage stable liquids of relatively low viscosity which when used as the isocyanate component in polyurethane formulations, particularly molded polyurethanes, give rise to highly resilient and useful molded products.