Study of deformation process of stored polymethacrylate free films.

In the present study the effects of the additives and of storage on the deformation of films prepared from methacrylic acid/ethyl acrylate copolymer with and without polysorbate 80 were evaluated. The films containing polysorbate 80 revealed a longer deformation process with a different deformation curve shape and higher force and work of deformation. Storage induced very significant changes in the characteristics of the films. The decrease in the deformation work was more relevant than the reduction in the deformation force. Increase of the storage time increased the changes in these parameters. The presence of polysorbate 80 in the films reduced the change in behaviour of the films at lower relative humidity.