| YUPO is stable and relatively unaffected by normal temperature changes. As with all thermoplastic films YUPO is affected by temperature extremes. Avoid temperatures in excess of 170° F (77° C).
1. Tensile and Tearing Strengths
At low temperatures, YUPO stiffens and becomes slightly brittle. Tensile and tearing strengths increase 5 to 10% when the temperature drops from 70 to 25° F (21 to ~ 32° C). However in the lower temperature ranges, elongation at failure decreases to just 25 to 30% of the level at room temperature. These affects are more pronounced in the grain direction. Folding endurance is not affected until temperatures drop below - 40° F (- 40° C). As temperature increases, tensile and tearing strengths decrease. The sheet, however, becomes more elastic, and elongation at failure increases, particularly in the machine direction.
2. Elevated temperatures have a marked affect on sheet dimensions and cause YUPO to shrink; the affect is more pronounced in the grain direction. The degree of shrinkage increases as a function of length of exposure and/or temperature increase. This shrinkage and resulting sheet deformation are permanent and cannot be reversed by cooling.
3. At temperatures above 170° F (77° C), sheets must be closely monitored to avoid permanent damage. Consequently, heat-set web offset printing is not recommended. Similarly, aqueous coating driers must be carefully controlled.
4. Ink adherence is usually unaffected by temperature changes, but specific applications should be tested under in-use conditions.
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