Blends of PBT and PVC have been made from mixed solutions of the polymers in 1-methyl-2-pyrrolidinone as the mutual solvent.
Characteristics of blends of three different compositions as well as three different molecular weights of PVC were studied with differential scanning calorimetry (DSC), Rheovibron and density measurements.
The DSC measurements reveal only single glass transition temperatures depending upon blend composition, which is apparently indicative of miscibility of the polymers.
The blends with 50/50 blend ratio show a large exothermic peak indicative of PBT crystallization in the glass transition region of PVC, which seems significant in this study.
The exothermic peak is considered as the result of crystallization of uncrystallized PBT trapped in PVC when quenched.
The dynamic mechanical measurements reveal only single glass transition peak for all the blends.
It is noted that a shoulder appears in the glass transition region of PVC for the blend with 50/50 blend ratio.
It is considered as the result of a rather large amount of crystallization of uncrystallized PBT.
The density measurements show that the measured densities of PBT/PVC blends are higher than those calculated by assuming volume additivity, which implies better packing because of specific interaction between the two components in the blends and a negative heat of mixing leading to miscibility.
