| 摘要 |
<p>The pistes, for use in winter resorts, are made by (a) preparing a bead polymer of small spheres which can be stuck to a base, pref. a moquette-type fabric; (b) depositing a first layer of 1.5-2 mm. thickness over the base; (c) depositing further layers with reducing thickness of 1.5-1mm.; and (d) finishing with a layer of 0.25mm. thickness. The polymer is pref. polyvinyl acetate of mol. wt. 77,000-250,000, giving a material which is very strong and elastic in the cold.</p> |
