Thermally insulating foam with vertically elongated cells

摘要

An extruded polymer foam has a polymer matrix with styrene-acrylonitrile copolymer and infrared attenuator and cell having an average size in the foam vertical direction of 150 micrometers or less, a ratio of vertical cell size to extrusion direction cell size that is greater than one and a cell anisotropic ratio that is greater than 1.1; the foam having a P-Ratio of 0.7 or less, less than 0.2 moles of hydrocarbon blowing agent in the cells per kilogram of foam; a density of 20-48 kilograms per cubic meter and a 25-year thermal conductivity that is 0.030 Waters per meter-Kelvin or less when free of fluorinated blowing agents and less than 0.029 Watts per meter-Kelvin when containing fluorinated blowing agent.