| 摘要 |
Corrugated plates are made of polyvinyl chloride resin, and are bidirectionally oriented in such a manner that an element which is sampled therefrom presents a retraction of at least 30 percent along the two main axes of the plates after a residence of 8 hours in an oven kept at 140 DEG C. The plates have a resiliency in tension at 20 DEG C in excess of 650 cm kgf/cm2 and a resiliency in prestressed condition in excess of 300 kfg/cm2. They are resistant at 4 DEG C to impacts caused by boxwood balls of 200 mm diameter which are projected perpendicularly against the surface of said plates at a speed such that their kinetic energy is 0.105 m kgf. |
