Abstract: An arrangement for enclosing an elongate substrate, e.g. a cable connection includes an outer resilient sleeve held in a radially-expanded configuration by being mounted on an inner holdout member, wherein the holdout member includes a generally tubular member that has a slit extending longitudinally thereof such that application of a force radially thereof causes the holdout member to reduce in circumference and to collapse around the substrate under the action of the recovery force of the outer resilient sleeve.

Abstract: A conductive material is provided which comprises a polymeric matrix having dispersed therein a conductive filler system comprising a minor proportion by weight of a relatively more conductive filler, and a major proportion by weight of a relatively less conductive filler. Preferred conductive materials may be used to provide stress relief for electrical apparatus and may be rendered heat recoverable.

Abstract: A two terminal circuit protection arrangement that: (1) is intended to be series connected in a line of the circuit; (2) comprises (a) a series switching transistor (1) that controls the line current, (b) a control transistor (4) that controls the base or gate voltage of the switching transistor and is responsive to an overcurrent through the switching transistor, and (c) a voltage source, for example a battery (3), a dc-dc converter (58/59) or a Seebeck device (43), applied to the base or gate of the switching transistor which biases the switching transistor into or toward conduction in normal operation; and (3) is capable of being remotely reset into a conducting state by stopping current in the line. The arrangement enables the initial voltage drop that is required to turn the switching transistor (1) on to be reduced or eliminated while requiring relatively little current from the voltage source. The arrangement can be reset remotely by briefly removing the voltage source or load from the circuit.

Abstract: A low-density polymer composition and use thereof in undersea flotation cables and the like, the composition comprising by volume based on the whole composition,(a) at least 30% of a polymer component consisting of (i) thermoplastic polyolefin elastomer of room temperature density less than 0.9 g/cc and/or (ii) thermoplastic olefin/(ester or acid) copolymer elastomer, and(b) at least 30% of micro-balls of room-temperature density less than 0.6 g/cc, at least 80%, preferably at least 90%, more preferably at least 95%, by weight, of the micro-balls having a maximum dimension less than 300 .mu.m, preferably less than 200 .mu.m.Preferred elastomers are metallocene-catalysed olefin copolymers of density 0.86-0.88 g/cc, and micro-balls of diameters 10-45, preferably 10-34, micrometers are advantageous in resisting pressures up to 50 MPa (5 km under sea).

Abstract: A hot-melt adhesive composition based on ethylene/vinyl actetate copolymer comprising not more than 35% (preferably not more than 30%, more preferably not more than 25%) by weight, based on the whole composition, of halogen-free char-forming flame-retardant additive(s) in an amount at least sufficient to prevent flaming drips generated on burning of the adhesive from igniting the underlying absorbent cotton according to the 20 mm Vertical Burn Test of Underwriters Laboratories Test Method UL-94 (1993), V-1, preferably V-0. Preferred halogen-free flame-retardant additives include ammonium phosphates, melamine cyanurate, zinc borate, and especially red phosphorus.

Abstract: Gels of oil-extended methacrylate-alkylene-methacrylate (M-A-M) triblock copolymers having higher glass transition temperatures than known styrene-alkylene-styrene triblock gels. The preferred M-A-M triblocks for making the new gels have polymethylmethacrylate end blocks and butadiene or ethylene/butylene mid-block, and are synthesised by methods in the public domain (inter alia Shell EP-A-0431706). Includes gels of new triblocks having end blocks of higher alkyl (e.g. isobornyl) methacrylate homopolymer or copolymers. Mixed methyl- and higher alkyl-methacrylate end blocks are preferred to reduce gel-formation problems which may arise from solubility parameter of homo-isobornylmethacrylate end blocks being too close to that of extender oil. Includes gels of new multi- (preferably penta-) block copolymers including styrene (S) blocks, e.g. M-S-A-S-M.

Abstract: An arrangement for protecting an electrical circuit such as a telephone circuit from a voltage transient comprises a voltage clamp or foldback device (3) arranged to be connected between a current-carrying line (1) and ground (1'), a capacitor (2) in series with it, and an inductance (4) series connected in the line. During normal operation the arrangement acts as an LC filter whose high frequency break-point is determined by the capacitance of the voltage clamp or foldback device (3) and the value of the inductance (4) which are chosen to give a break point of 1 kHz to 10 MHz. However, when the arrangement is subjected to a voltage transient, the voltage clamp or foldback device (3) fires causing the break-point to fall to a value determined by the values of the capacitor (2) and inductance (4). The arrangement may be used, for example, to protect the circuit against a rapid voltage drop caused by the firing of another circuit protection device such as a gas discharge tube 5.

Abstract: A two part range-taking member for providing a seal around a substrate includes a mating pair of resilient components for enclosing the substrate and a co-operating pair of rigid components for urging the resilient components into conformity with the substrate. The member may provide an electrical stress cone for a power cable, for example with two such members being provided in a cable joint.

Abstract: A 15 kv cable joint is enclosed within two half shells filled with sealant material. Displacement or thermal expansion of the sealant is accommodated by various configurations of stress cones that have apertures or surfaces that are flexible and arranged to maintain pressure on the sealant for example during thermal cycling of the joint.

Abstract: Heat-shrinkable sleeves of relatively opaque polymeric material having a relatively transparent integral strip (or other formation) to facilitate positioning of the sleeve on an article about which it is to be shrunk. The opaque portions of the sleeves preferably incorporate sufficient flame-retardant additives to compensate for the absence of such additives from the transparent portions, which transparent portions preferably occupy less of the sleeve surface than the opaque portions.

Abstract: A generally disc-shaped polymeric insulating article (14) is in two parts to fit around the core (4) of an insulator (2). A first part (22) of the article (14) is substantially C-shaped to fit around the insulator core (4), and the second part comprises an insert (30) that slidably engages the first part (22) so as to secure the article in place. The article (14) projects a substantial distance radially from the insulator (2) to prevent animals and the like, bridging the length of, and thus electrically short circuiting, the insulator (2).

Abstract: A 15 kv cable joint is enclosed within two half shells filled with sealant material. Displacement or thermal expansion of the sealant is accommodated by various configurations of stress cones that have apertures or surfaces that are flexible and arranged to maintain pressure on the sealant for example during thermal cycling of the joint.

Abstract: A switching arrangement that can be connected in a communications channel that comprises a pair of lines between sets of terminal equipment, which comprises: (i) a series switch (1,2) for connection in each of the lines; (ii) a shunt switch for connection between the lines; and (iii) a control circuit (5) that can actuate the series switches (1,2) and can actuate the shunt switch on receipt of a signal sent along the channel: wherein the control circuit (5) can actuate the shunt switch and the series switches (1,2) on receipt of one or more signals but the shunt switch will remain closed over a different time period than that during which the series switches remain open, in order to allow different tests to be performed on the channel, and wherein one or more of the switches comprises a solid state switch.

Abstract: A composite material having heat shrinkable fibers comprising LLDPE, characterized in that the LLDPE has a weight average molecular weight of from 55,000 to 130,000 and a crystallinity less than 60%.

Abstract: An arrangement for delivering an elastic sleeve on to an electric cable comprises an elastic sleeve (20) expanded radially on to a hollow rigid tubular support tube (18) with a tubular mesh (22) of plastics material interposed therebetween. The mesh (22) extends beyond one end of the support tube (18) and is then fed back through its hollow center. The one end of the tube (18) is disposed adjacent the end of the cable, and the mesh (22) within the tube (18) is progressively pulled so as to invert the sleeve (20) on to the cable end.

Abstract: A composite article is formed from yarn, comprising high strength fibres and fusible blocking material, and outer fusible material. The yarn is formed into its required shape and placed in a mould. The outer fusible material is introduced into the mould and its temperature is raised so as to melt the lower-melt temperature blocking fibres of the yarn. Under the action of temperature and pressure in the mould, the blocking material fuses so as to fill any interstices between the strength fibres, and the yarn is enclosed within the outer fusible material. The method is useful for forming electrical insulators of high strength glass fibre in the form of a loop (4) blocked against flow of moisture by polypropylene and enclosed within non-tracking polyethylene electrically insulating material (6).

Abstract: A method of making an object wherein known sheets having a curable prim receiving coating (epoxy and polyamide particles) on one surface and pressure-sensitive adhesive on the other surface (normally used for attaching the printed and cured sheet to a wall or other surface) are wrapped around the object to be marked and the overlapping ends of the sheet are temporarily secured by an overlap bond between the pressure-sensitive adhesive and the curable coating. Subsequent curing of the coating fixes the indicia printed thereon and cures the bond to fix the sheet in position. Preferably, the pressure-sensitive adhesive (e.g. acrylic polymer will interact with the curable coating on curing.

Abstract: A gel or gelloid composition contains (a) more than 50% by weight (based on total polymer content) of a block copolymer containing relatively hard blocks and relatively elastomeric blocks; (b) a polyphenylene ether; and (c) at least 500 parts by weight of an extender liquid per 100 parts by weight of the block copolymer, which liquid extends and softens the elastomeric blocks of the block copolymer. The polyphenylene ether is present in an amount sufficient to increase the softening or melting temperature of the gel or gelloid composition over that of the same composition without polyphenylene ether. The gel or gelloid composition is useful for sealing applications.

Abstract: A resiliently flexible ring of dimensionally heat-recoverable polymeric material whose tubular length is less than its notional circular diameter, formed so that it inherently maintains a non-circular open configuration enabling it to grip resiliently an object around which it is placed in use prior to heat-recovery, the maximum transverse dimension of the said object being at least 2.5% less, preferably at least 5% less, than the notional circular diameter of the ring. The ring preferably has at least three "corners" of relatively small radius of curvature, preferably evenly spaced around its circumference. Use of the rings is described for damping the noise of chain-drive sprocket wheels and for connecting flexible hoses to supply outlets.

Abstract: Polymer (preferably polyimide) sheets with laser ablated through-holes plated with metal are used for making electrical connections to specified microcircuits, especially unbumped microchips and Tape Automated Bonding (TAB) articles. Bonding with different melting-point materials at opposite ends of the plated holes is disclosed. Preferred polyimides are those derived from polymerisation of 4-4'-biphenyldianhydride and (4,4'-diaminobiphenyl, or 4,4'-diaminobiphenylether, or phenylenediamine, preferably p-phenylenediamine).