Abstract: A thermotropic liquid crystalline polymer matrix having sized carbon fibers incorporated therein for reinforcement. The carbon fibers are coated on their surface with a sizing composition comprising a rigid polyimide coating which is derived from the reaction of at least one aromatic diamine, at least one dianhydride, and at least one aromatic tetracarboxylic acid diester in which the carboxylic acid groups and ester groups are ortho disposed. By the use of appropriate amounts of heat and pressure, multifilamentary bundles of carbon fibers are readily impregnated with thermotropic liquid crystalline polymer to form a prepreg having a uniform distribution of carbon fiber throughout.

Abstract: The instant invention involves a process for use in preparing tapes or rovings, which are formed from a thermoplastic material used to impregnate longitudinally extended bundles of carbon fibers. The process involves the steps of (a) gas spreading a tow of carbon fibers; (b) feeding the spread tow into a crosshead die; (c) impregnating the tow in the die with a thermoplastic polymer; (d) withdrawing the impregnated tow from the die; and (e) gas cooling the impregnated tow with a jet of air.The crosshead die useful in the instant invention includes a horizontally extended, carbon fiber bundle inlet channel, means for providing melted polymer under pressure to the die, means for dividing the polymeric material flowing into the die into an upper flow channel and a lower flow channel disposed above and below the moving carbon fiber bundle, means for applying the thermoplastic material from both the upper and lower channels to the fiber bundle, and means for withdrawing the resulting tape from the die.

Abstract: A method for the production of composite articles by pultrusion is provided wherein the articles comprise thermotropic liquid crystalline polymers and reinforcing fibers. The liquid crystalline polymers employed exhibit physical characteristics such that the negative slope of a dynamic viscosity-frequency curve (as defined) is less than about 0.35. The use of polymers having such rheological characteristics enables a composite material to be produced by pultrusion in which the polymer is uniformly dispersed among the reinforcing fibers.