John Lee Murtha

Methods for evaluating the puncture and shear properties of pharmaceutical polymeric films

Abstract The tensile test is the most popular and widely used test for pharmaceutical films. From its data, the properties of Youngs modulus, elongation to break, break strength and energy to break can be calculated. These properties though, do not reflect completely the behavior of a film when subjected to puncture and shear. The utility of puncture and shear data was evaluated by comparing it to data generated under tension for cast films of the following polymers: sodium carboxymethylcellulose, hydroxyethyl cellulose, hydroxypropyl methylcellulose and sodium alginate. Each test provided a different measure of elongation, strength and energy under the stress vs strain curve. For example, the puncture test had an enhanced ability to differentiate elongation. On the other hand, energy to shear was less than would be expected based on tensile and puncture data. Puncture and shear results provided an enhanced ability to interpret data and predict behavior of a polymer in its finished application.