Abstract: Method of and apparatus for making a shaped crosslinked extruded polymeric product by extruding compacted, melted polymer, e.g., polyethylene, into a mixer formed on or fitted to the discharge end of an extruder, injecting proportionate amounts of a mixture of compounding ingredients including olefinically unsaturated hydrolyzable silane, free-radical generator and, preferably, a silanol condensation catalyst into the compacted, melted polymer. The polymer and compounding ingredients are blended in the mixer until the silane is grafted to said polymer, and the resulting grafted polymer mixed with the silanol condensation catalyst is extruded thruugh a die to form the product of the required final shape. The resulting product is subjected to the action of H.sub.2 O until the grafted polymer is crosslinked.

Abstract: A flexible heating element comprises at least two flexible electrical conductors spaced apart by a PTC material, an amorphous highly conductive rubber compatible with the PTC material and adhered to each conductor being interposed between the PTC material and each conductor whereby in use current passes from one conductor to another through the PTC material via the highly conductive rubber. The conductors are spaced sufficiently close to one another to ensure that when energized the PTC material heats substantially uniformly without exhibiting a significant temperature gradient between the conductors and that any abnormal temperature increase increases the temperature of all the PTC material between the conductors in the region of the abnormal temperature increase. The arrangement is such that in use the contact resistance between the conductors and the PTC material is reduced by the amorphous highly conductive rubber interposed therebetween.

Abstract: An extruder mixer for the extrusion of molten plastics and rubbers. The apparatus comprises a hollow cylindrical stator member and a cylindrical rotor member rotatable within the stator. The facing cylindrical surfaces carry rows of hemispherical cavities extending peripherally around the members so that the rows of one member are axially offset from rows of the other member whereby there is an axial overlap of the cavities and rotor. The cavities in adjacent rows on the rotor and stator are also circumferentially offset.

Abstract: A flexible heating element comprises at least two flexible electrical conductors spaced apart by a PTC material, an amorphous highly conductive rubber compatible with the PTC material and adhered to each conductor being interposed between the PTC material and each conductor whereby in use current passes from one conductor to another through the PTC material via the highly conductive rubber. The conductors are spaced sufficiently close to one another to ensure that when energised the PTC material heats substantially uniformly without exhibiting a significant temperature gradient between the conductors and that any abnormal temperature increase increases the temperature of all the PTC material between the conductors in the region of the abnormal temperature increase. The arrangement is such that in use the contact resistance between the conductors and the PTC material is reduced by the amorphous highly conductive rubber interposed therebetween.

Abstract: A mixing device having a flow path therethrough for material to be mixed includes a first plurality of radially extending, tapered rollers disposed between a first pair of relatively rotating raceways for subjecting the material to a milling action, a plurality of sets of alternately encountered stationary and moving teeth disposed in adjacent parallel planes for subjecting the material to a shearing action, and a second plurality of radially extending, tapered rollers disposed between a second pair of relatively rotating raceways for subjecting the material to a further milling action. The arrangement is such that a predetermined axial spacing between adjacent sets of the teeth is continuously maintained by means of the rollers and raceways.