Thermal analysis and topographical characterization of films of styrene‐butadiene blends

Abstract

Scanning probe microscopy (SPM) was used to study the thermal characteristics of latex films consisting of blends of two different styrene-butadiene copolymers with different glass transition temperatures (T g ). The resonance frequency (x) and the quality factor (Q p ) of an SPM probe oscillating above the sample surface were determined at different probe temperatures (T p ). Thermal transitions associated with a change in heat capacity were observed in the Dx-T p curves. The results were compared with differential scanning calorimetry measurements. The very slow heating rate used in the SPM method effectively eliminated the contribution of volumetric changes of the films around T g . Annealing of the samples in an oven did not influence the thermal transitions observed in the Dx-T p curves. The SPM method also enabled a novel approach for determining transition-induced dimensional changes (vertical contraction, expansion) of the films. Annealing was found to increase the dimensional stability of the blend films. The latex blends were also annealed by the SPM probe and the film progressed from particulate phase morphology to a continuous phase.