| 摘要 |
<p>Expanded particles of a monovinyl aromatic polymer (I) are produced by heating particles of (I) which contain a volatile fluid foaming agent (II) to a temp. 20-60 deg.C above the Tg of (I) so that they expand by at least 40 times their vol. at ambient temp. The resilient expanded particles are subjected to an atmosphere of an inert gas, e.g. air, capable of diffusing through the cell walls of the particles faster than (II) and are heated above the Tg of (I) so as to cause a further doubling in vol. (I) is crosslinked, e.g. by divinylbenzene, so that the unswollen particles have a swelling factor of 20-35 volumes in toluene and a crosslinking coefft. of 0.8-2.5.</p> |
