USE OF FTIR-ATR TO DETERMINE MOLECULAR ORIENTATION IN EXTRUDED PLASTIC SHEETS.

Dichroic ratio measured by FTIR-ATR technique provides valuable information to differentiate surface molecular orientation versus overall molecular orientation in extrusion process. Dichroic ratio measurement is very sensitive to changes in extrusion conditions. At same draw ratio, the overall frozen-in strain can be reduced by increasing either melt temperature or die temperature, while lower surface orientation can be obtained by increasing die temperature, decreasing melt temperature, or providing a faster cooling rate to the extrudate.