Ultimate heat seal and hot tack strengths have also been widely used to describe the performance of a sealant polymer. The characteristic of high heat seal strength is advantageous in a polymer, especially if the package is expected to survive rough handling during distribution. Hot tack is the ability of a hot or semi-molten seal to resist opening or separation as stress is applied. A complete description of hot tack testing and its usefulness was provided in a paper by Soutar (11). Hot tack has been correlated to on-line leakers during high-speed form/fill/seal packaging, where the stress on the molten seal in induced by the force of the product hitting the seal.
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