Investigation of deformation mechanisms during latex film formation by combination of unilateral NMR and near infrared measurements

Abstract

Unilateral solid state NMR and near infrared measurements are combined to study latex film formation at different temperatures and humidities in order to cover a broad parameter-space of film formation conditions. From analysis of nuclear magnetic resonance (NMR) data the time evolution of water and polymer fraction at different (vertical) positions in the film were estimated. The mean water fraction was determined simultaneously by near infrared (NIR) reflection measurements. From the time-evolution of the water distribution within the film and the total water content, it was possible to differentiate between the different deformation mechanisms (e.g. capillary deformation, receding water front mechanism or skin formation). The experimental findings are compared to theoretical predictions by Routh and Russel [Langmuir 15 (1999) 7762–7773]. Although most of the predicted regimes could be identified, the experimental estimated transitions between different regimes deviate significantly from the theoretical boundaries. The complex rheological behaviour of polymers has been identified to be the main reason for these deviations.