| abstract |
A recording device is described, useful as an integrated time-temperature or radiation-dosage history indicator. The device contains a substrate having deposited thereon at least two indicating units, one being unreacted and representing zero time of exposure and the other unit being pre-reacted. Each unit is comprised of an acetylenic compound containing at least one -C 3BOND C-C 3BOND C- group, capable of reacting by 1,4-addition polymerization thereby forming an end-point color after an irreversible, progressive color change upon thermal annealing or exposure to actinic radiation. The end-point color represents an integrated time-temperature history of thermal annealing or radiation-dosage history. Each unit is constructed such that the time required to form the end-point color by thermal annealing at a given temperature or for a known thermal history, or exposure to actinic radiation at a given average radiation dosage rate, is predetermined. A process is also described for using the device as well as an article having the device affixed thereto. |