| 摘要 |
<p>Alkenyl aromatic thermoplastic synthetic resinous elongate foam bodies having a machine direction, a traverse direction and closed noninterconnecting gas-containing cells are prepared using at least 70 percent by weight of 1,1,1-trifluoroethane and or 1,1,1,2-tetrafluoroethane as a blowing agent or part of a blowing agent mixture. These foam bodies have an average cell size of 0.01 to 0.3 millimeters, a density of from 0.75 to 6.0 pounds per cubic foot, an absolute dimensional stability of less than 4 percent in any direction when measured by the test designated ASTM D2126/C578, and preferably a minimum cross-sectional dimension of at least 0.25 inch, a cross-sectional area of at least 8 square inches, a water vapor permeability not greater than 1.8 perm inches. A cell size enlarger agent may be necessary for cell sizes in the 0.2-0.3 range.</p> |
