Abstract
Biodegradable polyester emulsions are generally hydrolyzed, the molecular weights are decreased, and their adhesive properties are deteriorated, even in indoor atmosphere. Therefore it is extensively required to estimate the life span of those adhesives by a simple but reliable method before their applications. Considering the fact that the threshold molecular weight at which adhesive property disappears is found to be different, depending on the cases, even if the same biodegradable emulsion is used, the following formula is derived to estimate the life span of those emulsion adhesives:Tx = (K1/Kx)T1where Tx is the life span of a particular specimen in the desired conditions, T1 the measured life span of the specimen in an accelerated condition, and K the apparent rate constant of the hydrolysis of the biodegradable polyester emulsion and the 1 and x mean the temperature in the accelerated condition and the desired condition, respectively. The estimated life span of polybutylene succinate-co-adipate emulsion is found to be similar to that determined experimentally and the other three specimens including heat-sealed paper, a piece of grindstone and the emulsion coated paper, are under way of testing.
