New Type of Thermoplastic Deformation

When certain thermoplastics are coated on a conducting substrate and uniformly charged and softened by heat, a wrinkling type of deformation occurs. It is found that the deformation will not occur below a critical value of the surface charge density. A mechanism is proposed in which the surface tension of the thermoplastic is reduced by the presence of the surface charge. Experimental results indicate that the surface potential at threshold varies as the one-half power of the film thickness, which is predicted by the mechanism proposed. A one-dimensional model is presented which predicts that a deformation will occur; however, quantitative agreement of the model with experimental data is not obtained.