COMPOSITIONS FOR COMPOUNDING, EXTRUSION AND MELT PROCESSING OF FOAMABLE AND CELLULAR POLYMERS

Abstract

In one aspect, the present invention relates to a communications cable, which comprises a support separator providing a plurality of channels for receiving transmission media, said support separator comprising a first polymeric material, at least one optical fiber disposed in one of said channels, at least an electrical conductor capable of carrying at least about 10 watts of electrical power disposed in another one of said channels, an insulation at least partially covering said electrical conductor, a jacket surrounding said support separator and said transmission media, said jacket comprising a second polymeric material. In some embodiments, the first and second polymeric materials can be the same material, and in other embodiments, they can be different materials.

Claims

1-33. (canceled)

34. A communications cable comprising: a support separator configured to provide a plurality of channels for receiving transmission media; at least an electrical conductor disposed in one of the plurality of channels, the at least one electrical conductor comprising an American Wire Gauge (AWG) in a range of about 18 and capable of carrying at least about 200 watts of electrical power; and a jacket configured to surround the support separator and any transmission media received by the plurality of channels; wherein at least one of the support separator and the jacket comprises a plurality of cellular structures, the cellular structures comprising one or more cells each comprising a size ranging from about 0.0005 inches to about 0.003 inches.

35. The communications cable of claim 34, wherein at least one of the support separator and the jacket comprises a foamed polymeric material.

36. The communications cable of claim 35, wherein the foamed polymeric material comprises a foaming level ranging from about 20% to about 70%.

37. The communications cable of claim 34, wherein the support separator and the jacket comprise different polymeric materials.

38. The communications cable of claim 34, further comprising at least one optical fiber disposed in at least another one of the plurality of channels.

39. The communications cable of claim 38, wherein the at least one optical fiber comprises at least one of a single-mode optical fiber or a multi-mode optical fiber.

40. The communications cable of claim 34, further comprising an insulation configured to at least partially cover the at least one electrical conductor.

41. The communications cable of claim 40, wherein the insulation comprises a foamed polymer.

42. The communications cable of claim 41, wherein the foamed polymeric material comprises a foaming level ranging from about 20% to about 70%.

43. The communications cable of claim 34, wherein the at least one electrical conductor is capable of carrying power in a range of about 10 watts to about 200 watts.

44. The communications cable of claim 34, wherein the jacket comprises an internal diameter equal to or less than about 0.4 inches.

45. The communications cable of claim 34, wherein the jacket comprises an internal diameter ranging from about 0.24 inches to about 0.32 inches.

46. The communications cable of claim 34, wherein at least one of the support separator and the jacket comprises a fluoropolymer.

47. The communications cable of claim 46, wherein the fluoropolymer comprises at least one of MFA, FEP, PFA, PVF, ETFE, ECTFE, and PVDF.

48. The communications cable of claim 46, wherein the fluoropolymer comprises a perfluoropolymer.

49. The communications cable of claim 48, wherein the perfluoropolymer comprises at least one of FEP, MFA, and PFA.

50. The communications cable of claim 34, wherein the at least one electrical conductor comprises a twisted pair conductor.

51. The communications cable of claim 34, wherein the one or more cells each comprises a size ranging from about 0.001 inches to about 0.002 inches.

52. The communications cable of claim 34, wherein at least about 60% to at least about 70% of the cellular structures comprise closed cells.

53. The communications cable of claim 34, wherein the jacket comprises a thickness ranging from about 0.005 inches to about 0.015 inches.

54. The communications cable of claim 34, further comprising a tape configured to surround the at least an electrical conductor.

55. The communications cable of claim 54, wherein the tape comprises at least one of a solid polymeric material and a foamed polymeric material.

56. The communications cable of claim 54, wherein the support separator, the jacket, and the tape comprise of different polymeric materials.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Features and advantages of the claimed subject matter will be apparent from the following description of embodiments consistent therewith, which the description should be considered in conjunction with the accompanying drawings.

[0042] FIG. 1 illustrates an embodiment of a jacketed Power over Ethernet 4-pair copper cable having five channels in one of which two fiber optic cables are disposed.

[0043] FIG. 2 illustrates an embodiment of a POE 4-pair copper cable having five channels with one closed channel in which two fiber optic cables are disposed.

[0044] FIG. 3 illustrates an embodiment of an POE cable according to the present teachings.

[0045] FIG. 4 illustrates another embodiment of a POE cable in which electrical conductors have foamed insulation.

[0046] FIG. 5 illustrates another embodiment of a POE cable according to the present teachings.

[0047] FIG. 6 schematically depicts the distribution of a plurality of thermocouples employed to measure the temperature at a plurality of locations within a bundle of cables,

[0048] FIG. 7 shows temperatures recorded by a plurality of thermocouples as a function of time at a plurality of different locations for a bundle of 192 cables each including 4 twisted pairs of copper wires disposed in an LSPVC jacket, where the copper wires were insulated with a layer of polyolefin

[0049] FIG. 8 shows equilibrium temperatures recorded by the thermocouples used to obtain the temperature data presented in FIG. 7,

[0050] FIG. 9 shows temperatures recorded by a plurality of thermocouples as a function of time at a plurality of locations for another bundle of 192 cables each including 4 twisted pairs of copper wires disposed in an LSPVC jacket, where the copper wires were insulated with a two-layer insulation formed via coextrusion of polyolefin and FEP,

[0051] FIG. 10 shows equilibrium temperatures recorded by the thermocouples used to obtain the temperature data presented in FIG. 9,

[0052] FIG. 11 shows temperatures recorded by a plurality of thermocouples as a function of time at a plurality of locations for a bundle of 192 cables each including 4 twisted pairs of copper wires disposed in an FEP jacket, where the copper wires were insulated with an insulation layer formed of FEP,

[0053] FIG. 12 shows equilibrium temperatures recorded by the thermocouples used to obtain the temperature data presented in FIG. 11,

[0054] FIG. 13 shows temperatures recorded by a plurality of thermocouples as a function of time at a plurality of locations for a bundle of 192 cables each including 4 twisted pairs of copper wires disposed in an foamed FEP jacket, where the copper wires were insulated with a layer of foamed FEP,

[0055] FIG. 14 shows equilibrium temperatures recorded by the thermocouples used to obtain the temperature data presented in FIG. 13,

[0056] FIG. 15 shows temperatures recorded by a plurality of thermocouples as a function of time at a plurality of locations for a bundle of 192 cables each including 4 twisted pairs of copper wires disposed in a foamed MFA jacket,

[0057] FIG. 16 shows equilibrium temperatures recorded by the thermocouples used to obtain the temperature data presented in FIG. 15, and

[0058] FIG. 17 shows measured and theoretically extrapolated temperature data for cable bundles formed of copper wires of different gauges.

DETAILED DESCRIPTION OF THE INVENTION

[0059] The present invention generally relates to communications cables that include different transmission media and can be used for transmission of data as well as electrical power. In many embodiments, the materials forming various components of the cable are selected to facilitate the dissipation of heat generated in the cable via passage of current therethrough. For example, in some embodiments a separator used to provide multiple channels in which transmission media are disposed, the insulation of the transmission media and the cable's jacket are formed of foamed fluoropolymers so as to facilitate the dissipation of heat generated in the cable. The use of foamed components also reduces the amount of flammable material in the cable. In some embodiments, the efficient dissipation of heat in a POE cable according to the present teachings allows forming such a cable in a compact manner, e.g., using a jacket with an inner diameter less than about 0.4 inches.

[0060] Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the compositions, devices, and methods of producing and making the communication cables disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the cables, cable components and methods of making the same specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

[0061] So that the invention may more readily be understood, certain terms are first defined.

[0062] As used herein, the terms about or approximately for any numerical values or ranges indicate a suitable dimensional tolerance that allows the composition, part, or collection of elements to function for its intended purpose as described herein. These terms indicate at most a ?5% variation about a central value.

[0063] The term cross-talk is used herein consistent with its common usage in the art to refer to electromagnetic interference between conductors, cables, or other electronic circuit elements.

[0064] The term engineered resin or engineering polymer as used herein refers to any of the following polymers: polyphenylenesulfide (PPS), polyetherimide (PEI), polysulfone (PSU), polypheylsulfone (PPSU), polyethersulfone (PES/PESU), polyetheretherketone (PEEK), polyaryletherketone (PAEK), polyetherketoneketone (PEKK), polyetherketone (PEK), or polyolefins such as polyethylene (PE), polyproplylene (PP), cyclic olefin copolymer (COC), polycarbonate (PC), polyphenylene ether (PPE), liquid crystal polymer (LCP), and/or combinations thereof.

[0065] The term fluoropolymer is used herein consistent with its common usage in the art to refer a polymer having at least one monomer that includes at least one fluorine atom.

[0066] The term per(halo)polymer is used herein consistent with its common usage in the art to refer to a polymer that includes monomers in which substantially all hydrogen atoms have been replaced with halogen atoms (e.g., fluorine, chlorine or bromine atoms).

[0067] The term perfluoropolymer is used herein consistent with its common usage in the art to refer to a fluoropolymer in which substantially all hydrogen atoms have been replaced with fluorine atoms.

[0068] As used herein, foaming level is the ratio of the volume of cells in a cellular structure, e.g. a cellular separator, relative to the total volume of the structure.

[0069] As used herein, the term melt-processable is meant that the polymer can be processed (i.e. fabricated into shaped articles, insulation(s), jacket coatings, films, fibers, tubes, wire coatings and the like) by conventional melt extruding, injecting or casting means.

[0070] The term thermoplastic as used herein, refers to polymers that are pliable or moldable above a specific temperature and return to a solid state upon cooling. These polymers have the property of becoming soft when they are heated and of becoming rigid again when they are cooled, without undergoing an appreciable chemical change. Such a definition may be found, for example, in the encyclopedia called Polymer Science Dictionary, Mark S. M. Alger, London School of Polymer Technology, Polytechnic of North London, UK, published by Elsevier Applied Science, 1989.

[0071] As used herein, the term elastomer is intended to designate a true elastomer or a polymer resin serving as a base constituent for obtaining a true elastomer. True elastomers are defined by the ASTM, Special Technical Bulletin, No. 184 standard as materials capable of being stretched, at room temperature, to twice their intrinsic length and which, once they have been released after holding them under tension for 5 minutes, return to within 10% of their initial length in the same time.

[0072] As used herein, the term active nucleating agent is intended to denote a compound which acts both as a nucleating agent and, at the same time, participates in blowing, by at least partially decomposing to yield gaseous components.

[0073] FIG. 1 schematically depicts a communication cable 100 according to an embodiment of the present teachings, which includes a support separator 101 providing five channels 110, 120, 130, 140, 150 for receiving transmission media. The support separator 101 includes a central portion 102 and a plurality of arms 103 extending radially from the central portion 102 such that the channels 110, 120, 130, 140, 150 are provided between the plurality of arms 103. In this embodiment, each arm 103 extends from the central portion 102 to a flap top portion 104A. In this embodiment, two adjacent flap top portions 104A partially enclose one of the channels 110, 120, 130, 140, 150. In other embodiment, at least two adjacent flap top portions can circumferentially extend so as to cooperatively substantially or completely enclose a channel (e.g., channel 150 in FIG. 2). In other embodiments, the arms of the separator may not extend to a flap top portion. Further, while in this embodiment the separator 101 is configured to provide five channels for receiving transmission media, in other embodiments, the number of channels can be less or more.

[0074] Although in this embodiment, the support separator 101 of the communications cable 100 is formed of a foamed polymeric material, in other embodiments, it can be formed of a solid polymeric material. In this embodiment, the foamed polymeric support separator can exhibit a foaming level in a range of about 20% to about 60%, about 20% to about 70%, or about 30% to about 60%. Further, the foamed separator can comprise a plurality of cellular structures characterized by a size in a range of about 0.0005 inches to about 0.003 inches or about 0.001 inches to about 0.002 inches. In some embodiments, at least about 60%, at least about 70%, or at least about 80% of the cellular structures can be in the form of closed cells.

[0075] The separator 101 can be formed of any suitable polymer. For example, the separator 101 can be formed of a fluoropolymer, such as a perfluoropolymer. Some examples of suitable polymeric materials include, without limitation, MFA (polytetrafluoroethylene-perfluoromethylvinylether), FEP (fluorinated ethylene propylene), PFA (perfluoroalkoxy), PVF (polyvinyl fluoride), ETFE (ethylene tetrafluoroethylene or (poly(ethylene-co-tetrafluoroethylene)), ECTFE (ethylene chlorotrifluoroethlyene), PVDF (polyvinylidene fluoride), and combinations thereof.

[0076] In some embodiments, the separator 101 can be formed of a non-halogenated polymer, i.e., engineered resin. Examples of engineered resins include, but are not limited to, polyphenylenesulfide (PPS), polyetherimide (PEI), polysulfone (PSU), polypheylsulfone (PPSU), polyethersulfone (PES/PESU), polyetheretherketone (PEEK), polyaryletherketone (PAEK), polyetherketoneketone (PEKK), polyetherketone (PEK), or polyolefins such as polyethylene (PE), polyproplylene (PP), cyclic olefin copolymer (COC), polycarbonate (PC), polyphenylene ether (PPE), liquid crystal polymer (LCP), and/or combinations thereof.

[0077] In this embodiment, a twisted pair of electrical conductors (e.g., copper wires) 111, 121, 131 and 141 is disposed in each of channels 110, 120, 130, and 140. Each twisted pair of electrical conductors 111, 121, 131 and 141 can be configured to carry electrical data, power, or combinations thereof. In this embodiment, the electrical conductors are configured to carry both power and communications data. For example, each twisted pair of electrical conductors 111, 121, 131 and 141 is capable of carrying at least about 10 watts of electrical power. By way of example, each twisted pair of electrical conductors can be capable of carrying electrical power in a range of about 10 watts to about 200 watts, e.g., in a range of about 20 watts to about 100 watts. In this embodiment, each electrical conductor can be configured to carry at least about 10 watts of power (e.g., 10 watts, 20 watts, 30 watts, 40 watts, 50 watts, 60 watts, or more than 60 watts). In some implementations, the electrical conductors of the twisted pairs can have a gauge (AWG) in a range of about 22 to about 26. Also, each twisted pair 111, 121, 131 and 141 can have an electrical insulation 113, 123, 133 and 143 wrapped around it.

[0078] The electrical insulation 113, 123, 133 and 143 of the communications cable 100, can be formed of a foamed or a solid polymeric material. In this embodiment, the insulation of the electrical conductors is formed of a solid polymeric material, such as a fluoropolymer (e.g., a perfluoropolymer). Some examples of suitable polymers include, without limitation, MFA (polytetrafluoroethylene-perfluoromethylvinylether), FEP (fluorinated ethylene propylene), PFA (perfluoroalkoxy), PVF (polyvinyl fluoride), ETFE (ethylene tetrafluoroethylene or (poly(ethylene-co-tetrafluoroethylene)), ECTFE (ethylene chlorotrifluoroethlyene), PVDF (polyvinylidene fluoride), and combinations thereof.

[0079] In other embodiments, such as some of the embodiments discussed below, electrical insulation 113, 123, 133 and 143 can be formed of a foamed polymer. In some such embodiments, the foamed polymer can exhibit a foaming level in a range of about 20% to about 60%, about 20% to about 70%, or about 30% to about 60%. In some embodiments, the foamed polymer can comprise a plurality of cellular structures (schematically depicted as circles) characterized by a size in a range of about 0.0005 inches to about 0.003 inches or about 0.001 inches to about 0.002 inches. In some embodiments, at least about 60%, at least about 70%, or at least about 80% of the cellular structures are closed cells.

[0080] In this embodiment, two optical fibers 151 and 152 are disposed within the channel 150. A variety of different types of optical fibers can be employed. For example, the optical fibers 151, 152 can be a single-mode or a multi-mode optical fiber for transmission of optical radiation (e.g., radiation at telecommunications wavelengths, e.g., at 1550 nm) from a proximal end of the cable to its distal end. The optical fibers 151, 152 are enclosed within a buffer tubes 153a and 153b.

[0081] The buffer tubes 153a and 153b can be formed of any suitable polymer. For example, the buffer tube can be formed of a fluoropolymer, such as a perfluoropolymer. Some examples of suitable materials for foaming the buffer tubes include, without limitation, MFA (polytetrafluoroethylene-perfluoromethylvinylether), FEP (fluorinated ethylene propylene), PFA (perfluoroalkoxy), PVF (polyvinyl fluoride), ETFE (ethylene tetrafluoroethylene or (poly(ethylene-co-tetrafluoroethylene)), ECTFE (ethylene chlorotrifluoroethlyene), PVDF (polyvinylidene fluoride), and combinations thereof.

[0082] In some embodiments, a tape 1 can enclose the electrical conductors and/or the optical fibers. [is this correct?] The tape 1 can be formed of a solid or foamed polymeric material, such as the polymers discussed above.

[0083] With continued reference to FIGS. 1 and 2, a jacket 105 surrounds the separator 101 and the transmission media disposed in the channels provided by the separator 101. The jacket 105 can be formed using any suitable polymer. Some examples of suitable polymeric materials include, without limitation, MFA (polytetrafluoroethylene-perfluoromethylvinylether), FEP (fluorinated ethylene propylene), PFA (perfluoroalkoxy), PVF (polyvinyl fluoride), ETFE (ethylene tetrafluoroethylene or (poly(ethylene-co-tetrafluoroethylene)), ECTFE (ethylene chlorotrifluoroethlyene), PVDF (polyvinylidene fluoride), and combinations thereof.

[0084] In some embodiments, the jacket 105 can have an internal diameter equal to or less than about 0.4 inches (about 10 mm). For example, the internal diameter of the jacket 105 can be in a range of about 0.24 inches (6 mm) to about 0.32 inches (8 mm) or in a range of about 0.24 inches (6 mm) to about 0.27 inches (7 mm). In some embodiments, the thickness of the jacket 105 can be from about 0.005 inches (0.127 mm) to about 0.015 inches (0.381 mm), or about 0.007 inches (0.18 mm) to about 0.010 inches (0.25 mm).

[0085] In some embodiments of a communications cable according to the present invention, a jacket surrounding the separator and the transmission media can be formed of a foamed polymeric material. By way of example, FIG. 3 schematically depicts a communications cable 100 that is similar to the communications cable 100 discussed in connection with FIGS. 1 and 2 except that the communications cable 100 includes a foamed jacket 105. More specifically, similar to the communications cable 100, the communications cable 100 includes the foamed separator 101, which provides five channels 110, 120, 130, 140, and 150. The twisted pairs of electrical conductors 111, 121, 131, and 141 are disposed, respectively, in the channels 110, 120, 130, and 140. Each twisted pair can carry electrical data, power, or combinations thereof. In some embodiments, the electrical conductors of the twisted pairs can have a gauge (AWG) in a range of about 18 to about 28. The electrical insulations 112, 122, 132, and 142 surround the twisted pairs 111, 121, 131, and 141. The optical fibers 151 and 152 are disposed within the channel 150.

[0086] As noted above, in this embodiment, the jacket 105 is formed of a foamed polymeric material. By way of example, the jacket 105 can be formed of a foamed fluoropolymer, e.g., a foamed perfluoropolymer. Some examples of suitable fluoropolymers can include, without limitation, MFA (polytetrafluoroethylene-perfluoromethylvinylether), FEP (fluorinated ethylene propylene), PFA (perfluoroalkoxy), PVF (polyvinyl fluoride), ETFE (ethylene tetrafluoroethylene or (poly(ethylene-co-tetrafluoroethylene)), ECTFE (ethylene chlorotrifluoroethlyene), PVDF (polyvinylidene fluoride), and combinations thereof.

[0087] In some embodiments, the foamed jacket 105 can exhibit a foaming level in a range of about 20% to about 60%, about 20% to about 70%, or about 30% to about 60%. In some embodiments, the foamed jacket can comprise a plurality of cellular structures (herein depicted schematically by a plurality of small circles distributed through the jacket) characterized by a size in a range of about 0.0005 inches to about 0.003 inches or about 0.001 inches to about 0.002 inches. In some embodiments, at least about 60%, at least about 70%, or at least about 80% of the cellular structures are closed.

[0088] The foamed jacket 105 can provide certain advantages. For example, by forming the jacket of a foamed polymeric material, the amount of flammable material in the communications cable can be reduced. Further, the foamed jacket helps dissipate the heat generated inside the cable to the external environment.

[0089] The thickness of the jacket can be, for example, in a range of about 0.005 inches to about 0.015 inches, though other thicknesses may also be utilized.

[0090] In some embodiments, not only the separator and the jacket are formed of foamed polymeric materials, but also the insulation surrounding one or more of the electrical conductors disposed in the channels provided by the separator are formed of foamed polymeric materials. By way of example, FIG. 4 schematically depicts another embodiment 100 of a communications cable according to an embodiment of the present teachings, which is similar in all respects to the communications cable 100 discussed above in connection with FIG. 3, except that in this embodiment, each of the electrical conductors of the twisted pairs has a foamed insulation. More specifically, twisted pairs of electrical conductors 111, 121, 131, and 141 are disposed, respectively, in the channels 110, 120, 130, and 140. Each electrical conductor of each twisted pair includes a foamed insulation. By way of example, the twisted pair 111 includes two electrical conductors 111a and 111b, where the electrical conductor 111a includes a foamed insulation 113a and the electrical conductor 111b includes a foamed insulation 113b. Similarly, the twisted pair 121 includes electrical conductors 121a and 121b having, respectively, foamed insulations 122a and 122b. The twisted pairs 131 includes electrical conductors 131a and 131b having, respectively, foamed insulations 132a and 132b, and the twisted pair 141 includes electrical conductors 141a and 141b having, respectively, foamed insulations 142a and 142b.

[0091] In some embodiments, the foamed insulation can have a foaming level in a range of about 20% to about 60%, about 20% to about 70%, or about 30% to about 60%. Further, the foamed polymeric material can comprise a plurality of cellular structures (depicted schematically herein by a plurality of circles distributed within the insulation) characterized by a size in a range of about 0.0005 inches to about 0.003 inches or about 0.001 inches to about 0.002 inches. In some embodiments, at least about 60%, at least about 70%, or at least about 80%, of the cellular structures are closed.

[0092] The use of foamed insulation for the electrical conductors in the communications cable 100 can provide certain advantages. For example, it reduces the amount of potentially flammable material inside the cable, and it can in some cases help with heat management by facilitating the dissipation of heat generated in the electrical conductor.

[0093] Similar to the previous embodiments, in this embodiment, the jacket 105 has an inner diameter less than about 0.4 inches, e.g., in a range of about 0.24 inches to about 0.4 inches.

[0094] In some embodiments, in addition to the separator, the jacket, the insulation of the electrical conductor, the bufferings of the fiber optics disposed in the communications cable can also be formed of a foamed polymeric material, such as fluoropolymer materials. Some suitable polymeric materials are those discussed above. By way of example, FIG. 5 schematically depicts such an embodiment 1000, which is similar to the communications cable 100 discussed in connection with FIG. 4, except that in this embodiment the fiber optic bufferings are formed of a foamed polymer. More specifically, the communications cable 1000 includes two fiber optics 151 and 152 disposed in one of the channels provided by the separator 101. The fiber optic 151 includes a foamed buffering 152 and the fiber optic 152 includes a foamed buffering 153. The foaming level of the foamed bufferings can be, for example, in a range of about 20% to about 70%, though other foaming levels can also be employed.

[0095] A variety of known techniques can be employed to fabricate a communications cable according to the present teachings, such as the embodiments discussed above. For example, the foaming of various components of the communications cable, such as, the separator, the wire insulation, the jacket and/or the fiber optic bufferings, can be made using chemical foaming and/or gas-injection foaming techniques. By way of example, in some embodiments, the compositions and methods disclosed in U.S. Pat. Nos. 7,968,613, 8,278,366, 8,318,819, 8,877,823, and 8,912,243, each of which is herein incorporated by reference in its entirety, can be employed to foam various components of a communication cable according to the present teachings, such as the separator, the jacket, the wire insulation, etc. Further, known cable manufacturing and assembly techniques, including known extrusion techniques, can be used to fabricate various cables according to the present teachings.

[0096] A communications cable according to the invention provides a number of advantages. For example, it allows the use of different transmission media within the same cable. In addition, it allows transmission of not only data but also electrical power. In addition, a communication cable according to the teachings of the invention allows efficient management of heat generated within the cable. In particular, as discussed above, in many embodiments one or more components of the cable, e.g., a separator used for providing channels in which transmission media are disposed and/or a jacket of the cable, are formed of foamed polymers (e.g., foamed fluoropolymers), which allow the heat generated within the cable to be efficiently dissipated. The efficient management of the heat generated within the cable in turn allows a compact construction of the cable. For example, in many embodiments, the inner diameter of the cable jacket can be less than about 0.4 inches.

EXAMPLES

Example 1

[0097] The thermal behavior of five cable bundles, each including 192 cables, was studied using a test protocol commonly known as the U.L. test protocol. The temperatures at different locations within each cable bundle were monitored by employing a plurality of thermocouples distributed approximately as shown in FIG. 6.

I. Solid Polyolefin Insulation

[0098] A bundle of 192 cables each including 4-twisted pairs of copper wires disposed in an LSPVC jacket was tested. The cables were manufactured using well known extrusion techniques. Each copper wire was selected to have a 23 AWG and was insulated with a layer of polyolefin. The cables did not include a separator for separating different twisted pairs from one another. FIG. 7 shows temperatures recorded by the thermocouples as a function of time for different currents flowing through each cable. FIG. 8 shows the equilibrium temperatures recorded by the thermocouples for this cable bundle. This cable bundle showed a temperature rise of greater than 60? C. for an ambient temperature of 45? C. and a current of 0.5 amperes flowing through each cable, thus not meeting the temperature rating for the U.L. requirement.

II. Solid Polyolefin/FEP Coextruded Insulation

[0099] A bundle of 192 cables each including 4-twisted pairs of copper wires disposed in an LSPVC jacket was tested. The cables were manufactured using well known extrusion techniques. Each copper wire was selected to have a 23 AWG and was insulated with a two-layer insulation formed via coextrusion of polyolefin and FEP. The cables did not include a separator for separating different twisted pairs from one another. FIG. 9 shows temperatures recorded by the thermocouples as a function of time for different currents flowing through each cable. FIG. 10 shows the equilibrium temperatures recorded by the thermocouples for this cable bundle. This cable bundle also showed a temperature rise of greater than 60? C. for an ambient temperature of 45? C. and a current of 0.5 amperes flowing through each cable, thus not meeting the temperature rating for the U.L. requirement.

III. All Solid FEP Insulation, Crossweb and Jacket

[0100] A bundle of 192 cables each including 4-twisted pairs of copper wires disposed in a jacket formed of FEP was tested. The cables were manufactured using well known extrusion techniques. Each copper wire was selected to have a 23 AWG and was insulated with an insulation layer formed of FEP. Each cable further included a crossweb formed of FEP providing separate channels in each of which one of the twisted pairs was disposed. FIG. 11 shows the temperatures recorded by the thermocouples as a function of time for different currents flowing through each cable. FIG. 12 shows the equilibrium temperatures recorded by the thermocouples. The data shows that this cable bundle exhibited much enhanced thermal properties relative to the previous two cables.

IV. All Foamed FEP Insulation, Crossweb and Jacket

[0101] A bundle of 192 cables each including 4-twisted pairs of copper wires disposed in a jacket formed of foamed FEP was tested. The cables were manufactured using well known extrusion techniques. Each copper wire was selected to have a 23 AWG and was insulated with an insulation layer formed of foamed FEP. Each cable further included a crossweb formed of foamed FEP providing separate channels in each of which one of the twisted pairs was disposed. The foaming of the insulation, crossweb and the jacket was achieved via chemical foaming using talc. FIG. 13 shows the temperatures recorded by the thermocouples as a function of time for different currents flowing through each cable. FIG. 14 shows the equilibrium temperatures recorded by the thermocouples. This cable exhibited acceptable temperature rise up to 0.9 amperes.

V. All Foamed MFA Insulation, Crossweb and Jacket

[0102] A bundle of 192 cables each including 4-twisted pairs of copper wires disposed in a jacket formed of foamed MFA was tested. The cables were manufactured using well known extrusion techniques. Each copper wire was selected to have a 23 AWG and was insulated with an insulation layer formed of foamed MFA. The cable further included a crossweb formed of foamed MFA providing separate channels in each of which one of the twisted pairs was disposed. The foaming of the insulation, crossweb and the jacket was achieved via chemical foaming using talc. FIG. 15 shows the temperatures recorded by the thermocouples as a function of time for different currents flowing through each cable. FIG. 16 shows the equilibrium temperatures recorded by the thermocouples. This cable bundle exhibited acceptable temperature rise up to 1 ampere of current through each cable, the maximum current that was applied to the cables.

Example 2

[0103] The data presented in FIG. 17 shows that the gauge of the copper wires can have a significant impact on the temperature rise within a cable bundle as a function of current flowing through the cables. The data for a cable bundle with copper wires having a gauge of 23 AWG corresponds to the data for the cable bundles discussed above in Example 1. The data for the other gauges were obtained via extrapolation of the 23 AWG data based on the Ohmic resistance of the copper conductors using the following relation:

[00001]$\begin{array}{cc}?.Math..Math.T_{\mathrm{AWG}}=R_{\mathrm{AWG}}?\left(\frac{?.Math..Math.T_{23.Math..Math.\mathrm{AWG}}}{R_{23.Math..Math.\mathrm{AWG}}}\right)& \mathrm{Eq}..Math.\left(1\right)\end{array}$

[0104] where,

[0105] ?T.sub.AWG indicates theoretically extrapolated change in temperature (relative to ambient temperature) [0106] R.sub.AWG represents the Ohmic resistance of the wire used in the cable for which temperature extrapolation is desired, [0107] ?T.sub.23AWG represents measured temperature change for a cable bundle in which the copper wires have a gauge of 23 AWG, and [0108] R.sub.23AWG represents the Ohmic resistance of a copper wire having a gauge of 23 AWG.

[0109] Those having ordinary skill in the art will appreciate that various changes can be made to the above embodiments without departing from the scope of the invention.