The phenomenon of the occurrence of a middle-temperature thermal effect in
crystallizable multiblock thermoplastic elastomers, the so-called annealing
endotherm has not yet been univocally explained, hence, it was subjected t
o DSC analysis. The formation of this endotherm in response to the time and
temperature of conditioning (stabilization) of the sample has bene followe
d. The investigation have been per formed for a specific polymer system, po
ly(tetramethylene terephthalate)- block-poly(oxytetramethylene)-block-polyl
aurolactam (PBT-b-TPMO-b-PA12)-(n). The specific property of this elastomer
is the solubility or a partial solubility of one of the components (PBT bl
ock) in the two remaining ones being mutually insoluble. The occurrence of
the tow different amorphous phases (PBT and PA12) in this elastomer wit gla
ss transition temperatures T-g >20 degreesC is also possible. This specific
system permits to observe an interesting phenomenon, since at the points d
etermining the middle-temperatures of the glass transition temperatures of
the elastomer, the two small endotherms are shaping; after proper stabilisa
tion they are approaching each other, and as a result of this process they
would form one extreme. This extreme comprises the thermal effect of the di
spersion of the mesomorphic aggregates being the intermediate form between
the amorphous state and the crystalline state. The mesomorphic aggregates c
onstitute the additional network points of the physical polymer network of
the elastomer.