Plastics for Telecommunications

Re 164. [Hexed] Polyedier polyurethane con for moisture blocks and pressure dams in paper, pulp, and plastic insulated telecommunications cable. 

Fire safety for plastics in telecommunications depends on the type of components under consideration, and their location, as much as the specific pol mier material from which they are made. The products vary from small consumer items to high voltage cables. Therefore, the safety requirements for a range of applications must be set quite differently, although the expected lifetime conditions for a component may not always be clearly known or forecast. 

Lithium-metal-polymer (LMP) is a relatively new technology being promoted by the Canadian Avestor Limited Partnership based in Boucherville, Quebec, for telecommunications applications. Avestor s LMP cell is built up from four elements. An ultra-thin metallic lithium foil anode combines the roles of lithium source and current collector. The solid polymeric electrolyte is made by dissolving a lithium salt in an appropriate co-polymer. The metallic oxide cathode is based on a reversible intercalation compound of vanadium oxide, blended with a lithium salt and a polymer to produce a plastic composite. Finally, an aluminium foil forms the current collector. Avestor cells can operate within the temperature range -40 °C to +65 °C. 

The trend for miniaturisation is countered by the considerably increased proportion of plastics in telecommunications equipment and the overall consumption of plastics by the industry has increased significantly. 

Automatic assembly processes will not only add to the scope for telecommunications equipment but will also make their own special demand on plastics, including heat and solvent resistances. 

The market for telecommunications equipment is becoming increasingly competitive and attractive appearance is essential so that plastic housings offer the possibility of producing attractive shapes in a range of colours at relatively low cost. 

Plastics and polymeric materials in general already constitute a major proportion of the material content of the telecommunications equipment now being designed and manufactured. The opportunities for plastics in telecommunications equipment are great and the use of plastics by the industry will remain at a high and increasing level for many years to come. 

The bulk of plastics materials are required to operate within the range of -30 to + 100°C. There has, however, been a steadily increasing demand for materials to operate outside of these ranges, particularly in certain aerospace, military and telecommunications applications. A considerable amount of research work has been carried out in response to this demand and many thousands of polymers, both organic and inorganic, have been prepared. Many of those which have achieved commercial use have been considered in earlier chapters but in the final part of this chapter it is intended to review the overall situation. 

Light wave technologies provide a number of special challenges for polymeric materials. Polymer fibers offer the best potential for optical communications in local area network (LAN) applications, because their large core size makes it relatively cheap to attach connectors to them. There is a need for polymer fibers that have low losses and that can transmit the bandwidths needed for LAN applications the aciylate and methacrylate polymers now under study have poor loss and bandwidth performance. Research on monomer purification, polymerization to precise molecular-size distributions, and weU-controlled drawing processes is relevant here. There is also a need for precision plastic molding processes for mass prodnction of optical fiber connectors and splice hardware. A tenfold reduction in the cost of fiber and related devices is necessaiy to make the utilization of optical fiber and related devices economical for local area networks and tlie telecommunications loop. 

Telecommunications, the watch industry, medical applications, and the automotive and chemical industries are asking for smaller and smaller parts and components made of plastic. Standard injection machines are unsuitable for micro-parts. Here we describe, without claiming to be ejdiaustive, two examples of special machinery developed by Battenfeld and Medical Murray. 

Recently, optical telecommunications tliat transmit large amounts of information via light signals have been rapidly replacing conventional electrical telecommunications. Optical polymers, such as poly(methylmethacrylate) (PMMA), polystyrene (PS), and polycarbonate (PC) are used for plastic optical fibers and waveguides. However, these polymers do not have enough Ihermal... 

Nowadays the electronic appliances used for entertainment, telecommunications and data processing are widespread in daily life. Typical examples include televisions, video recorders, hi-fi systems and fax machines, not to mention computers with their peripherals such as monitors and printers, scanners and copiers. These devices are predominantly made of polymeric components and materials which might contain additives, such as flame retardants and plasticizers (Wensing, Uhde and Salthammer, 2005) to obtain specific desired properties. In addition, there will also be chemical residues from production and processing aids, such as residual monomers and solvents. Especially under operating conditions these compounds can be released from electronic equipment into indoor air due to the heating-up of the device interior. In many cases, such emissions can be monitored via simple odor tests (Walpot, 1996). 

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