| 摘要 |
Process for the prodn. of bands from an extruded sheet consisting of at least one crystallisable poly-alpha-alkene comprises (a) drawing the extruded sheet, while it is still above the crystalline m.p. of the polymer, in a direction across the direction of extrusion, to 1.2-4.0 x, pref. 1.2-2.0x its original length, (b) drawing the sheet, while it is at a temp. below the crystalline m.p. of the polymer, in the direction of extrusion, and (c) cutting the sheet into bands, either before or after the drawing operation (b). Stage (a) can be carried out on the sheet when it is in tubular form, and orientation can be imparted in the lengthwise direction as well as the transverse direction. |
