| 摘要 |
For extrusion of closed cell polymer foams, composns. etc. used contg. (A) polyolefins, (B) 5-20 wt.% impact-resistant polystyrene, acrylic elastomers or monomers; sorbitan tioleate or monostearate, glycol monostearate or a combination of these, (C) a particulate seed-forming system and (D) a combination of >=2 normally gaseous blowing agents with substantially different vapour pressures and solubilities in the polymer mixt. (B) is pref. polystyrene or acrylic elastomer (esp. impact-resistant polystyrene contg. 5-10% elastomer), which serves as a barrier material to retard escape of gas, and to increase the melt strength. (D) is pref. a mixt. of CCl2F2 and CHClF2. The composns. give closed cell foams suitable for shock absorption and insulation, with improved mechanical props. |
