NOVELTY - A rigid, closed cell polymeric foam (f1) comprises 70-96 wt.% of foamable polymer; 2-12 wt.% of blowing agent e.g. hydrofluorocarbons; and 0.01-10 wt.% of polyaramid having branched fibrous structure dispersed throughout the foam (f1). The foam (f1) maintains dimensional stability such that the foam (f1) expands not greater than 1% in direction upon exposure to a temperature of at least 180 degrees F for 1 hour.    USE - As a rigid, closed cell polymeric foam used in shear web of wind blade; and a rigid, closed cell polymeric foam insulation board used as roofing insulation (claimed).    ADVANTAGE - The rigid, closed cell polymeric foam maintains dimensional stability such that the foam expands not greater than 1% in direction upon exposure to a temperature of at least 180 degrees F for 1 hour. The rigid polymeric foam exhibits an open or closed cell polymeric foam structure. The extruded polymeric foam contains fibrous additives as service temperature enhancing agent that increases the maximum service temperature of foam without detrimentally affecting its physical or thermal properties, and without requiring change in the extrusion manufacturing process. The foamable polymer is the backbone of the formulation and provides strength, flexibility, toughness, and durability to the final product. The foamable polymer is preferably chemically stable, i.e. generally non-reactive, within the expected temperature range during formation and subsequent use in a polymeric foam.    DETAILED DESCRIPTION - A rigid, closed cell polymeric foam (f1) comprises 70-96 wt.% of foamable polymer; 2-12 wt.% of blowing agent; and 0.01-10 wt.% of polyaramid having branched fibrous structure dispersed throughout the foam (f1). The blowing agent is selected from hydrofluorocarbons, hydrofluoroolefins, 1-9C aliphatic hydrocarbons, 1-4C aliphatic alcohols, carbon dioxide, acetone, natural gases, water, ketones, ethers, methyl formate and/or hydrogen peroxide. The foam (f1) maintains dimensional stability such that the foam (f1) expands not greater than 1% in direction upon exposure to a temperature of at least 180 degrees F for 1 hour. INDEPENDENT CLAIMS are included for the following:    (1) wind blade comprising root; spar; shell; surface; and shear web comprising the foam (F1); and    (2) rigid, closed cell polymeric foam insulation board comprises 70-96 wt.% of polystyrene; 2-12 wt.% of blowing agent; and 0.01-10 wt.% of polyaramid having branched fibrous structure dispersed throughout the insulation board, where the blowing agent is selected from hydrofluorocarbons, hydrofluoroolefins, 1-9C aliphatic hydrocarbons, 1-4C aliphatic alcohols, carbon dioxide, acetone, natural gases, air, water, ketones, ethers, methyl formate and/or hydrogen peroxide, where the insulation board maintains dimensional stability such that the foam (f1) expands not greater than 1% in direction upon exposure to a temperature of at least 180 degrees F for 1 hour.