Inventors:
Robert G. Hanlon - Indianapolis IN
Joe A. Craig - Speedway IN
Leigh B. Bangs - Midland MI
Assignee:
The Dow Chemical Company - Midland MI
International Classification:
C09K 300
Abstract:
A nonreversible freeze-thaw indicator which will detect whether an article has been subjected to freezing or thawing conditions comprising an encapsulated translucent to opaque colloidal dispersion of organic solid particles suspended in a liquid medium, said colloidal dispersion having the property of becoming nonreversibly destablized upon freezing which thereafter provides a telltale visual sign if said dispersion rises through its freeze-thaw temperature. After the colloidal dispersion has once been frozen to trigger its irreversible destabilization and is again thawed, it coagulates to form a non-flowing waxy gel, flocculates and precipitates leaving a clear liquid and a coagulated solids layer or partially flocculates to transform a translucent dispersion to a substantially opaque dispersion.