Montgomery M. Alger

Gas barrier improvement using vermiculite and mica in polymer films

Abstract The objective of this work was to develop a class of barrier materials based on filling a polymer film with impermeable plates aligned in the plane of the film. Mica and vermiculite fillers were developed for this application, and permeability reductions of more than two orders of magnitude were achieved in solvent cast films. The fillers will not survive extrusion but could provide the basis for high barrier coatings.

Simplified chemical-physical theory for liquid metal solutions—II. Composition dependence of the gibbs energy

Abstract The composition dependence of the Gibbs energy, enthalpy and entropy of mixing are considered with the simplified chemical-physical theory model. Analytical expressions for all thermodynamic functions and derivatives are given in terms of the model parameters. The Darken stability function is shown to exhibit peaks in the compound-forming Group IIB-VA liquid metal systems. The separate enthalpic and entropic contributions to the Darken function are shown to be much larger than the Darken function but of opposite sign so they tend to cancel. Additional examples of the Darken function and its component parts are given for several binary magnesium systems which exhibit very large negative deviations from ideal mixing behaviour.

Measurement of Co2 Permeability in Polymer Films

A simple and sensitive method for measuring CO2 permeability in polymer films has been developed. The method is based on the use of 14CO2. At time zero 14CO2 is injected on the high pressure side of the cell. Permeation is monitored with a Geiger counter which senses 14CO2 on the low pressure side of the cell. The counts/time on the low pressure side are proportional to the total concentration of CO 2 which has diffused through the film. With the known source concentration the volume-time curve is constructed and the permeability and time lag are calculated. The system sensitivity as it is presently configured is on the order of 10-15 em3(STP).cm/cm2.sec.cm Hg. Results are presented for a measurement of a 0.025 cm polycarbonate film.