Abstract: A method is described of producing a laminated structural material which includes the steps of stacking alternately layers of thermoplastics sheet material and one or more layers of material to be laminated, the material having been impregnated with a second thermoplastics material prior to stacking, placing the stack in a pre-heated mould or press and subjecting the stack to heat and pressure for a time sufficient to cause the thermoplastics material to flow and bond together the layers of structural material to be laminated and allowing the mould or press to cool sufficiently to avoid distortion of the moulded part before removal from the mould or press.

Abstract: A material suitable for thermosetting includes a collection of hollow particles adhesively mixed with a thermosetting resin in such proportions that the mixture exists in a granular form and may be converted by thermosetting into a fused solid mass having a density not greater than 0.5 grams per cubic centimeter.The particles may be glass microbubbles or phenolic microballoons and the resin may be a hardenable Friedel-Crafts resin. The material according to the invention is more suitable for packing into shaped cavities than known resins including those containing filler particles.

Abstract: High strength, high modulus reinforcement fibres having a greatest cross-sectional dimension of about 100 .mu.m or less and suitable for setting in a matrix material, e.g. resin, are characterized by a cross-sectional shape which is or approximates to a flat-sided polygon of three or more sides, preferably three sides.

Abstract: A method of producing a composite material in which a reinforcing material (eg as fibres) is embedded in a matrix material is characterized in that the reinforcement material comprises a polymer material having a draw ratio of at least 12:1 which is plama treated, prior to incorporation in the matrix, preferably to produce pitting in its surface whereby improved adhesion is obtained between the reinforcement material and the matrix material by mechanical interlocking of the pitted surface of the reinforcement material and the complementary surface of the matrix material. Preferably, the surface pitting is effected by a plasma discharge treatment. Preferably the average pit size is from 0.1 to 4 microns.

Abstract: A material suitable for thermosetting includes a collection of hollow particles adhesively mixed with a thermosetting resin in such proportions that the mixture exists in a granular form and may be converted by thermosetting into a fused solid mass having a density not greater than 0.5 grams per cubic centimeter.The particles may be glass microbubbles or phenolic microballoons and the resin may be a hardenable Friedel-Crafts resin. The material according to the invention is more suitable for packing into shaped cavities than known resins including those containing filler particles.