Abstract: Elastomeric block co-polyesters having improved elastic and work recovery properties, a high melting point and are stable at high temperatures, have hard segments comprising at least 50 mole percent of polyethylene terephthalate groups and soft segments comprising at least 40 weight percent of the block copolyester. The soft segments, which have a defined structure, are formed by reacting phenolic compounds with a mixture of ethylene oxide and propylene oxide/butylene oxide.

Abstract: An immobilized enzyme structure in which molecules of one or more enzymes are attached to chemically active groups located on surface in the structure, such structure being composed of melt spun polyamide fibres comprising spaced fibrils of polyamide which are substantially aligned to the axis of the fibre, such aligned spaced fibrils being interconnected to each other in a random manner.

Abstract: Elastomeric block co-polyesters having improved elastic and work recovery properties, a high melting point and are stable at high temperatures, have hard segments comprising at least 50 mole percent of polyethylene terephthalate groups and soft segments comprising at least 40 weight percent of the block copolyester. The soft segments, which have a defined structure, are formed by reacting phenolic compounds with a mixture of ethylene oxide and propylene oxide/butylene oxide.

Abstract: A melt spun fiber or tube having two polymeric fibrous components and containing from 30 to 70 parts by weight of a first component and from 70 to 30 parts by weight of a second component, each component being present in the fiber or wall of the tube as fibrils which are substantially aligned to the axis of the fiber or tube the aligned fibrils being interconnected to each other in a random manner, the interconnections penetrating through the fibrils of the other component such that both components exist in the fiber or tube wall as interpenetrating networks.

Abstract: A monofilament or multifilament sports racket string, of a thermoplastic aromatic polyetherketone and preferably polyetheretherketone, such string preferably having an elongation not exceeding 5% when a tensile stress of at least 100 Newtons/mm.sup.2 is applied along the axis of the string and preferably having a dynamic stiffness, measured at a mean stress of 175 Newtons/mm.sup.2, of not greater than 1.150 times the dynamic stiffness measured at a mean tensile stress of 80 Newtons/mm.sup.2.