Abstract: A structural thermoplastic composite material comprises a laminate of a first layer of a fibre reinforced thermoformable crystalline polymer composite and an adherent layer of a second thermoformable polymer which has been applied to the first layer at a temperature above the melting point of the polymer of the first layer. The second polymer comprises an amorphous polymer having a Tg which is at least 10.degree. C. lower than the Tm of the other polymer, which is crystallisable in a subsequent annealing process, and which has a peak crystallisation time of at least 1 minute. Such a material can be bonded to itself or to a different material by the adherent layer at temperatures below the Tm of the matrix polymer.

Abstract: A structural thermoplastic composite material comprises a laminate of a first layer of a fibre reinforced thermoformable polymer composite containing reinforcing filaments and an adherent layer of a second thermoformable polymer. The thermoformable polymer of the adherent layer comprises either a crystalline polymer having a melting point at least 10.degree. C. below that of the first layer, or is an amorphous polymer having a glass transition temperature which is at least 10.degree. C. lower than the melting point of the polymer of the first layer, or is an amorphous polymer which may be crystallizable in a subsquent annealing process. The adherent layer is applied to the first layer at a temperature above the melting point of the thermoformable polymer of the first layer.

Abstract: A process of producing a structural network from a semicrystalline, melt crystallizable polyarylene ether or polyarylene thioether comprising providing a molten mixture of at least one semicrystalline polymer in the presence of a melt plasticizer for the polymer which melt contains at least some polymer entities having a crystalline form, the total polymer concentration being between 5 and 50% by weight of the mixture of polymer and melt plasticizer, and heating the mixture of polymer and melt plasticizer at a heating rate of between 1.degree. C./hour and 1000.degree. C./hr, preferably between 10.degree. C./hour and 100.degree. C./hour until the mixture is at a temperature in the range 10.degree. C. below to 20.degree. C. above its clearing point and cooling the mixture until it solidifies whereby an open cell structure essentially free from granular superstructure is obtained.