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Continuous polymeric extrusion nucleation systems and methods useful for making polymeric microcellular foamed materials, including crystalline and semi-crystalline polymeric microcellular materials, are provided. Pressure drop rate is an important feature in some embodiments, and the invention prov

Continuous polymeric extrusion nucleation systems and methods useful for making polymeric microcellular foamed materials, including crystalline and semi-crystalline polymeric microcellular materials, are provided. Pressure drop rate is an important feature in some embodiments, and the invention provides systems for controlling these and other parameters. One aspect involves a multiple-pathway nucleator that is separated from a shaping die by a residence chamber. Another aspect involves a die for making advantageously thick articles, including a multiple-pathway nucleation section. Microcellular material can be continuously extruded onto wire, resulting in a very thin, essentially closed-cell microcellular insulating coating secured to a wire. Other very thin microcellular products can be fabricated as well.

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1. A method comprising:establishing a stream of polymeric material flowing at a rate of at least about 5 lbs per hour within a polymer processing space between a rotating screw and an extruder barrel; introducing, into the stream of polymeric material, a blowing agent through a plurality of orifices

1. A method comprising:establishing a stream of polymeric material flowing at a rate of at least about 5 lbs per hour within a polymer processing space between a rotating screw and an extruder barrel; introducing, into the stream of polymeric material, a blowing agent through a plurality of orifices of the extruder barrel while passing the orifices with a flight of the rotating screw; and admixing the polymeric material and the blowing agent to form a single-phase solution of polymeric material and blowing agent, wherein the blowing agent is present in the single-phase solution in an amount less than about 80 percent saturation concentration as determined at the lowest pressure in the extruder barrel after the point of blowing agent injection and prior to nucleating the single-phase solution. 2. The method of claim 1, further comprising nucleating the single-phase solution of polymeric material and blowing agent at a pressure drop rate of at least about 0.1 GPa/scc to create sites of nucleation.3. The method of claim 1, further comprising nucleating the single-phase solution of polymeric material and blowing agent at a rate sufficient to form microcellular polymeric material.4. The method of claim 1, wherein the flight of the rotating screw passes each orifice at a rate of at least 1 pass per second.5. The method of claim 1, comprising introducing, into the stream of polymeric material the blowing agent through at least about 100 orifice.6. The method of claim 1, wherein at least some of the orifices are located at different radial positions around the extruder barrel.7. The method of claim 1, comprising passing the orifices with an un-broken flight of a screw.8. The method of claim 1, wherein the flight of the rotating screw periodically blocks each orifice.9. The method of claim 1, wherein the blowing agent is a supercritical fluid in the extruder barrel.10. The method of claim 1, further comprising extruding the single-phase solution to form a microcellular polymeric material.11. The method of claim 10, further comprising nucleating the single-phase solution while extruding the solution through a die.12. The method of claim 11, wherein the pressure drop rate increases in a downstream direction, while exuding the solution trough the die.13. The method of claim 1, further comprising metering the mass of the blowing agent introduced into the stream of polymeric material.14. The method of claim 1, wherein the stream of fluid, polymeric material is established in the extruder at a rate of at least about 40 lbs per hour.15. The method of claim 1, further comprising nucleating the single-phase solution to form a polymeric foam material.16. The method of claim 1, further comprising:nucleating the single-phase solution at a rate sufficient to form a microcellular polymeric material; and forming a microcellular polymeric material. 17. The method of claim 16, wherein the microcellular polymeric material includes cells of size less than about 100 microns.18. The method of claim 16, wherein the microcellular polymeric material has an average cell size of less the about 50 microns.19. The method of claim 16, wherein the microcellular polymeric material has a maximum cell size of about 100 microns.20. The method of claim 16, wherein the microcellular polymeric material has a maximum cell s of about 50 microns.21. The method of claim 16, wherein the microcellular polymeric material has a void fraction of less than about 50%.22. The method of claim, 16, wherein the microcellular polymeric material has a void fraction of less than about 20%.23. The method of claim 16 wherein the microcellular polymeric material is essentially closed-cell.24. The method of claim 16, wherein the microcellular polymeric material has a moisture absorption of less than about 0.1% by weight.25. The method of claim 16, wherein the blowing agent concentration is less than about 4% by weight based on the weight of the polymeric material and blowing agent solution.26. The method of claim 25 wherein the blowing agent is carbon dioxide and the polymeric material is substantially free of a nucleating aid.27. The method of claim 16, wherein the blowing agent concentration is less than about 2% by weight based on the weight of the polymeric material and blowing agent solution.28. The method of claim 27, wherein the blowing agent is carbon dioxide and the polymeric material is substantially free of a nucleating aid.29. The method of claim 16, wherein the blowing agent concentration is less than about 0.5% by weight based on the weight of the polymeric material and blowing agent solution.30. The method of claim 29, wherein the blowing agent is nitrogen and the polymeric material is substantially fee of a nucleating aid.31. The method of claim 16, wherein the polymeric material is substantially free of a nucleating aid.32. The method of claim 16, comprising forming the single-phase solution in the polymer process space between the rotating screw and the extruder barrel.33. The method of claim 32, further comprising cooling the single-phase solution in the polymer processing space between the rotating screw and the extruders barrel.34. The method of claim 16, comprising:forming the single-phase solution in the polymer pressing space between the rotating screw and the extruder barrel; cooling the single-phase solution in the polymer processing space between the rotating screw and the extruder barrel; and nucleating the single-phase solution by passing the single-phase solution through a nucleating pathway in a die and releasing from the die into ambient conditions a microcellular polymeric material. 35. The method of claim 34, comprising introducing, into the stream of polymeric material the blowing agent through at least about 10 orifices.36. The method of claim 34, wherein the pressure after the point of blowing agent injection and prior to nucleating the single-phase solution varies by no more than about 1500 psi.37. The method of claim 34, wherein the blowing agent is carbon dioxide and the polymeric material is polystyrene.38. The method of claim 16, wherein the pressure after the point of blowing agent injection and prior to nucleating the single-phase solution varies by no more than about 1500 psi.39. The method of claim 16, further comprising dividing the single-phase solution into separate portions and separately nucleating the separate portions at a rate sufficient to form a microcellular polymeric material.40. The method of claim 39, further comprising re-combining the separate portions.41. The method of claim 40, further comprising forming the microcellular polymeric material from the re-combined separate portions.42. The method of claim 41, wherein the microcellular polymeric material forms an article having a thickness of less than about 4 mm.43. The method of claim 16, wherein forming the microcellular polymeric material comprises extruding microcellular polymeric material as a coating around a wire.44. The method of claim 43, wherein the coating is less than about 4 mm.45. The method of claim 43, wherein the coating is less than about 0.1 mm.46. The method of claim 1, further comprising dividing the single-phase solution into separate portions and separately nucleating the separate portions.47. The method of claim 1, comprising introducing, into the stream of polymeric material, the blowing agent through at least about 10 orifices.48. The method of claim 1, wherein the blowing agent comprises carbon dioxide.49. The method of claim 1, wherein the blowing agent comprises nitrogen.50. The method of claim 1, further comprising nucleating the single-phase solution of polymeric material and blowing agent at a pressure drop rate of at least about 1.0 GPa/sec to create sites of nucleation.51. The method of claim 1, wherein the same type of blowing agent is introduced through each of the ports.52. The method of claim 11, comprising nucleating the single-phase solution by passing the solution through a single nucleating pathway in the die.53. The method of claim 52, further comprising releasing the nucleated single-phase solution from the die into ambient conditions.54. A method comprising continuously extruding microcellular polymeric material from a single-phase solution of polymeric material and blowing agent contained in extrusion apparatus including a nucleating pathway, the blowing agent in the solution in an amount less than about 80 percent saturation concentration as determined at the lowest pressure in the system after the point of blowing agent injection prior to the nucleating pathway.55. The method of claim 54, comprising continuously extruding microcellular polymeric material having cells of less than about 50 microns average size.56. The method of claim 54, comprising maintaining the steam, downstream of blowing agent injection location and upstream of the nucleation region, within the extruder, under pressure not less tan about 2000 psi and not greater than about 4500 psi.57. The method of claim 54, further comprising nucleating the single-phase solution of polymeric material and blowing agent at a pressure drop ate of at least about 0.1 GPa/scc to create sites of nucleation by passing the solution through the nucleating pathway.58. The method of claim 54, wherein the nucleating pathway is located within a die of the extrusion apparatus and further comprising nucleating the solution while extruding the solution through the die.59. The method of claim 54, wherein the microcellular polymeric material includes cells of size less than about 100 microns.60. The method of claim 54, wherein the microcellular polymeric material has a maximum cell size of about 100 microns.61. The method of claim 54, wherein the microcellular polymeric material has a maximum cell size of about 50 microns.62. The method of claim 54, wherein the microcellular polymeric material has a void fraction of less than about 50%.63. The method of claim 54, wherein the microcellular polymeric material has a void fraction of less than about 20%.64. The method of claim 54, wherein the microcellular polymeric material is essentially closed-cell.65. The method of claim 54, wherein the microcellular polymeric material has a moisture absorption of less than about 0.1% by weight.66. The method of claim 54, wherein the blowing agent concentration is less than about 4% by weight based on the weight of the polymeric material and blowing agent solution.67. The method of claim 66, wherein the blowing agent is carbon dioxide and the polymeric material is substantially free of a nucleating aid.68. The method of claim 54, wherein the blowing agent concentration is less than about 2% by weight based on the weight of the polymeric material and blowing agent solution.69. The method of claim 68, wherein the blowing agent is carbon dioxide and the polymeric material is substantially free of a nucleating aid.70. The method of claim 54, wherein the blowing agent concentration is less than about 0.5% by weight based on the weight of the polymeric material and blowing agent solution.71. The method of claim 70, wherein the blowing agent is nitrogen and the polymeric material is substantially free of a nucleating aid.72. The method of claim 54, wherein the polymeric material is substantially free of a nucleating aid.73. The method of claim 54, comprising forming single-phase solution in the polymer processing space between the rotating screw and the extruder barrel.74. The method of claim 73, further comprising cooling the single-phase solution in the polymer processing space between the rotating screw and the extruder barrel.75. The method of claim 54, comprising:forming the single-phase solution the polymer processing space between the rotating screw and she extruder barrel; cooling the single-phase solution in the polymer processing space between the rotating screw and the extruder barrel; and nucleating the single-phase solution by passing the single-phase solution through a nucleating pathway in a die and relet from the die into ambient conditions a microcellular polymeric material. 76. The method of claim 75, wherein the pressure after the point of blowing agent injection and prior to nucleating the single-phase solution varies by no more than about 1500 psi.77. The method of claim 75, wherein the blowing agent is carbon dioxide and polymeric material is polystyrene.78. The method of claim 54, comprising introducing, into the stream of polymeric material, the blowing agent through at least 10 orifices.79. The method of claim 54, wherein the pressure after the point of blowing agent injection and prior to nucleating the single-phase solution varies by no more than about 1500 psi.80. The method of claim 54, further comprising dividing the single-phase solution into separate portions and separately nucleating the separate portions in respective nucleating pathways.81. The method of claim 54, wherein the blowing agent comprises carbon dioxide.82. The method of claim 54, wherein the blowing agent comprises nitrogen.83. The method of claim 54, further comprising nucleating the single-phase solution of polymeric material and blowing agent at a pressure drop rate of at least about 1.0 GPa/sec to create sites of nucleation.84. The method of claim 54, comprising continuously extruding microcellular polymeric material as a coating around a wire.85. The method of claim 84, wherein the coating is less than about 4 mm.86. The method of claim 84, wherein the coating is less than about 0.1 mm.87. The method of claim 84, wherein the blowing agent comprises carbon dioxide or nitrogen.88. The method of claim 54, comprising introducing, into the stream of polymeric material, the blowing agent through a plurality of orifices.89. The method of claim 58, further comprising releasing the nucleated single phase solution from the die into ambient conditions.90. The method of claim 58, wherein the nucleating pathway is a single nucleating pathway.91. A method comprising:providing a single-phase solution of polymeric material and blowing agent wherein the blowing agent is present in the single-phase solution in an amount less than about 80percent saturation concentration as determined at the lowest pressure in the extruder bare after the point of blowing agent injection and prior to nucleating the single-phase solution; and continuously extruding said single-phase solution through an orifice constructed and arranged to provide a microcellular polymeric material having an average cross-sectional dimension of less than 0.5 mm. 92. The method of claim 91, further comprising nucleating the single-phase solution of polymeric meal and blowing agent at a pressure drop rate of at least about 0.1 GPa/see to create sites of nucleation.93. The method of claim 91, comprising nucleating the solution while extruding the solution through a die.94. A comprising: establishing a stream of lye material flow a rate of at least about 5 lbs per hour within a polymer processing space between a rotating screw and an extruder barrel;introducing, into the stream of polymeric material, the blowing agent through at least about 10 orifices of the extruder barrel while passing the orifice with a fit of the rotating screw; and admixing the polymeric material and the blowing agent to form a single-phase solution of polymeric material and blowing agent. 95. The method of claim 94, further comprising nucleating the single-phase solution to form a polymeric foam material.96. The method of claim 94, further comprising: nucleating the single-phase solution at a rate sufficient to form a microcellular polymeric material; andforming a microcellular polymeric material. 97. The method of claim 96, wherein the microcellular polymeric material includes cells of 6size less than about 100 microns.98. The method of claim 96, wherein the microcellular polymeric material has an average cell size of less than about 50 microns.99. The method of claim 96, wherein the blowing agent is present in the single-phase solution in an amount less than about 80 percent saturation concentration as determined at the lowest pressure in the extruder barrel after the point of blowing agent injection and prior to nucleating the single-phase solution.100. The method of claim 96, wherein the blowing agent concentration is less than about 4% by weight based on the weight of the polymeric material and blowing agent solution.101. The method of claim 100, wherein the blowing agent is carbon dioxide and the polymeric material is substantially free of a nucleating aid.102. The method of claim 96, wherein the blowing agent concentration is less than about 2% by weight based on the weight of the polymeric material and blowing agent solution.103. The method of claim 102 wherein the blowing agent is carbon dioxide and the polymeric material is substantially free of a nucleating aid.104. The method of claim 96, wherein the blowing agent concentration is less than about 0.5% by weight based on the weight of the polymeric material and blowing agent solution.105. The method of claim 104, wherein the blowing agent is nitrogen and the polymeric material is substantially free of a nucleating aid.106. The method of claim 96, wherein Me polymeric material is substantially free of a nucleating aid.107. The method of claim 96, comprising forming the single-phase solution in the polymer processing space between the rotating screw and the extruder barrel.108. The method of claim 107, further comprising cooling the single-phase solution in the polymer processing space between the rotating screw and the extruder barrel.109. The method of claim 96, comprising:forming the single-phase solution in the polymer processing space between the rotating screw and the extruder barrel; cooling the single-phase solution in the polymer processing spice between the rotating screw and the extruder barrel; and nucleating the single-phase solution by passing the single-phase solution through a nucleating pathway in a die and releasing from the die into ambient conditions a microcellular polymeric material. 110. The method of claim 109, wherein the pressure after the point of blowing agent injection and prior to nucleating the single-phase solution varies by no more than about 1500 psi.111. The method of claim 96, wherein the process after the point of blowing agent injection and prior to nucleating the single-phase solution varies by no more than about 1500 psi.112. The method of claim 96, wherein forming the microcellular polymeric material comprises extruding microcellular polymeric material as a coating around a wire.113. The method of claim 112, wherein the coating is less than about 4 mm.114. The method of claim 112, wherein the coating is less than about 0.1 mm.115. The method of claim 96, further comprising dividing the single-phase solution into separate portions and separately nucleating the separate portions at a rate sufficient to form a microcellular polymeric material.116. The method of claim 115, further comprising re-combining the separate portions.117. The method of claim 116, comprising forming the microcellular polymeric material from the recombined separate portions.118. The method of claim 117, wherein the microcellular polymeric material forms an article having a thickness of less than about 4 mm.119. The method of claim 94, comprising introducing, into the stream of polymeric material, the blowing agent through at least about 100 orifices.120. The method of claim 94, further comprising dividing the single-phase solution into separate portions and separately nucleating the separate portions.121. The method of claim 94, wherein the blowing agent comprises carbon dioxide.122. The method of claiming 94, wherein the blowing agent comprises nitrogen.123. The method of claim 94, further comprising nucleating the single-phase solution of polymeric material and blowing agent at a pressure drop rate of at least about 0.1 GPa/sec to create sites of nucleation.124. The method of claim 94, wherein the same type of blowing agent is introduced through each of the ports.