Draw ratio effect orientation angle

The effect of an orientation process on an isolated elliptic flaw is depicted in Figure 7A. Let < i and a2 be the permanent stretch (or draw) ratios (ratio of drawn to undrawn length) to which the master sheet is subjected in two orthogonal directions. If an elliptic flaw is originally at right angles to the ai direction (i.e.y p = ir/2) and a2 = 1, then R will increase with until a particular value of is reached at which R = 1. For larger values of i, R will then decrease but the major axis of the ellipse is now at ft = 0. The critical draw ratio at which the orientation P jumps from tt/2 to 0 and for which the ellipse is circular (R = 1) is described later. 

Figure 7. A. Schematic of an elliptic flaw initially at right angles to the draw direction. For a uniaxial draw, the draw ratio D = at. At a critical draw ratio D = I/R the ellipse becomes circular. For higher draw ratios (D > I/R), the ellipse forms with a 90° change in its orientation. B. Schematic of the effect of increasing draw ratio on an ellipse initially at some angle other than 90° to the draw direction. C. A general biaxial draw (al9 a2) acting on an ellipse at initial orientation pto the, major drawm direction (a. > as).

Physically, the flaws with R > 80° are more effectively blunted than are flaws at a lower angle to the draw direction. Above the critical draw ratio, they are oriented close to the draw direction (low R ) and account... 

To obtain an insight into the effect of the draw ratio on the molecular orientation of the Vectra phase, wide angle x-ray diffraction, WAXD, was utilized and the results for the Ultem/Vectra 70/30 sheet drawn in the first zone are shown in Figure 11. For the sample with the lowest draw ratio, a sharp Debye ring corresponding to a d-spacing of 0.46 nm is observed. This observation is in agreement with previous data on Vectra reported in the literature (10). As the draw ratio increases, the azimuthal dependence of the... 

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