| 摘要 |
A rigid or semi-rigid plastics sheet material comprises a pair of opposed faces (20, 22) between which run elongate voids defined by interconnections (24, 25) between the two opposite faces, the cross-sectional shape of at least some of the voids being a polygon with more than four sides, preferably a repeating pattern of regular hexagons or octagons joined in a line at adjacent sides or apices and including triangular secondary voids therebetween. Advantages include higher strength, lighter weight and faster cooling during the extrusion process.
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