Abstract: A water purification apparatus comprising a semi-permeable membrane capable of being contacted with a water source; a superabsorbent polymer capable of absorbing water across said semi-permeable membrane; a pressure application surface capable of transmitting pressure to the gel; and a permeable membrane through which absorbed water is capable of being released from the gel upon application of pressure thereto from said pressure application surface, wherein said permeable membrane is isolated in use from the water source by an isolation means

Abstract: An optically active film composite comprising a transparent substrate and at least one layer of a block copolymer blend comprising between 30:70 to 70:30 percent by volume of each component of the copolymer, the block copolymer forming lamellar microdomains of each polymeric component, which components have different refractive indices. The thickness of the lamellae may be controlled through selection of molecular weights of the components and by the addition of compatible homopolymers.

Abstract: Urea-isocyanurate copolymers are obtained by the reaction of:(a) an organic polyisocyanate compound,(b) a polyamino compound having at least two amino groups connected by a flexible chain, and(c) optionally an amino chain extender in which the amino groups are substantially less reactive towards the polyisocyanate (a) than are the amino groups of compound (b), the reaction being effected in the presence of(d) a trimerisation catalyst effective to convert a polyisocyanate to a polyisocyanurate in the reaction the ratio of the number of equivalents of isocyanate groups to the total number of moles of amino groups is at least 8.7, and the ratio of the number of equivalents of chain extender (c)--if used--to the number of equivalents of polyamino compound (b) is a maximum of 5:1.The copolymers are especially useful for producing articles by Structural Reaction Injection Moulding.