Polymer Engineering Faculty Research


A Real Time Study on Drying and the Mechano-Optical Behavior of Polyvinyl Alcohol Films in Solid and Swollen State

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Summer 6-12-2015


In this paper, we investigate film drying followed by mechano-optical behavior of PVA films in solid and swollen state, respectively. During drying the real time evolution of thickness, weight, and birefringence (both in and out of plane) are captured using a highly instrumented measurement system. During drying, initially isotropic solution rapidly loses water and beyond a critical stage it develops optical anisotropy in the thickness direction as reflected in rapid development of out of plane birefringence while in-plane isotropy is maintained. Stretching the dried films in the solid state yields three regimes of non-linear stress and strain-optical behavior. The temperature shows a positive effect on the birefringence value at given true strain levels. Swelling the PVA films with water, facilitate room temperature stretchability, hence providing a route of stretching that avoids decomposition and discoloration that occurs at elevated temperatures. The effects of moisture content on mechano-optical properties of PVA films are mapped and opposite dependences of photolelastic and strain optical constants on moisture content are observed.

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