| 摘要 |
Foamed alkenyl aromatic polymer of density 8-128 (pref. 16-90) kg/cu.m having closed gas-filled cells of size 0.1-2.5 mm is obtd. from polymer (I) of mol. wt. 100,000-350,000 (150,000-300,000) prepd. from 99-70 (95-80) wt.% of an alkenyl-aromatic monomer (pref. styrene or vinyltoluene) and 1-30 (5-20) wt.% of pref. acrylic acid, or methacrylic or itaconic acid or mixts., by blending heat plastified (I) with 0.5-20 pph of a blowing agent (II) at a temp. to decompose (II) and under sufficient pressure to prevent foaming, and subsequently extruding into a zone of lower pressure. (II) is typically a carbonate or bicarbonate of Na, Mg, Zn or NH4, or mixts. thereof; NaHCO3 is pref. II are safe and permit an increase in latitude in the operating process. The procedure avoids the use of the prior art volatile halocarbons and possible hazards associated with their eventual release into the atmos. |
