Thermal behavior of polyamide-12 and poly (styrene-co-acrylonitrile) blend

In this work, an unusual morphology of a mixture of polyamide-12 (PA-12) with a series of poly (styrene-co-acrylonitrile) (SAN) was obtained by solution casting and fast solvent evaporation. The prepared film was transparent although it contained many crystals. These crystals apparently prevented phase separation despite the instability of the PA-12 and SAN mixtures below 180 degrees C. In isothermal experiments, once the crystals were melted, phase separation began and the scattered intensity fit the Cahn-Hilliard theory. When the AN content in the SAN copolymer was less than 5%, the phase separation took place when only part of the crystals were melted at 180 degrees C. However, due to the constraint of unmelted crystals, the growth rate of phase separation at this temperature was much slower.