C16
Effect of Sample Geometry and Dimensions on the Fracture of Natural Rubber Vulcanizates
Width, length, width to length ratio, shape and volume define the geometry of bulk specimens. Therefore, we focused on the effects of geometry on the strength of edge-cut NR specimens and their ability to strain-crystallize.
Sample geometry, width and thickness in combination, affect strength that results from strain-crystallization. Because relatively thick specimens have significant stress in the thickness direction and in the remaining width (wR), the width in front of the cut tip is the actual width sustaining stretch. Thus, samples with high thickness/wR ratio (0.84 in this study) promote strain-crystallization when cut depth is near the critical value. When the thickness/wR ratio < 0.84 and wR > 4mm, the thickness effect is minute. However, when the thickness/wR ratio < 0.84 and wR < 1.3mm, some specimens promote strain-crystallization, but some do not.