Full-field optical thickness profilometry of semitransparent thin films with transmission densitometry

A novel bidirectional thickness profilometer based on transmission densitometry was designed to measure the localized thickness of semitransparent films on a dynamic manufacturing line. The densitometer model shows that, for materials with extinction coefficients between 0.3 and 2.9?D/mm, 100-500microm measurements can be recorded with less than +/-5% error at more than 10,000 locations in real time. As a demonstration application, the thickness profiles of 75mmx100?mm regions of polymer electrolyte membrane (PEM) were determined by converting the optical density of the sample to thickness with the Beer-Lambert law. The PEM extinction coefficient was determined to be 1.4D/mm, with an average thickness error of 4.7%.

Effect of gamma Irradiation on Latex Film Dissolution

Latex films have been prepared by annealing pyrene (Py)-labeled poly(methyl methacrylate)-polyisobutylene particles at the glass transition temperature (100 degrees C). These films were then irradiated by gamma rays from (60)Co in a gamma cell at room temperature at various dose rates (rad/h). Before dissolution the films were annealed at 200 degrees C for a 30 min time interval to complete the film formation process. Steady-state fluorescence techniques were used to monitor the dissolution of irradiated latex films. Dissolution of films in a chloroform-heptane (80%-20%) mixture was monitored in real time by the Py fluorescence intensity change. Relaxation constants, k(0), and dissolution coefficients, D(d), of polymer chains were measured. Two different regimes of D(d) values were observed during dissolution, which are related to two different molecular weight distributions caused by scission and branching of polymer chains when they were irradiated and annealed. Copyright 2001 Academic Press.

An overview of polymer latex film formation and properties

The literature on polymer latex film formation has grown enormously in recent times--driven by the need to find alternatives for solvent-based systems with their adverse environmental impacts. Although greater insight has been shown by the use of modern instrumental techniques such as small angle neutron scattering, direct non-radiative energy transfer and atomic force microscopy, the actual mechanisms involved in deforming spherical particles into void-free films are still the subject of controversy and debate. Surfactant-free homopolymer model colloid latices, favoured in academic studies, together with latices containing surfactants whose redistribution can influence film properties, and the more complex copolymer, blended, core-shell and pigmented systems needed to satisfy a full range of film properties are all considered.