Production of high porosity open-cell membranes
a technology of open-cell membranes and membranes, which is applied in the direction of membranes, cell components, separation processes, etc., can solve the problem of significant shrinkage of films in the thickness direction
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Problems solved by technology
Method used
Image
Examples
example 1
[0094] A polymer solution was prepared with the following formulation heated in a pressure chamber to 60° C. and 20 psig with stirring: 1 part Kynar 2801 PVDF-HFP copolymer; 1 part Kynar 761 PVDF homopolymer, 4 parts Kynar 301F PVDF homopolymer, 90.5 parts acetone (industrial grade), 3.5 parts water.
[0095] The solution was allowed to cool to room temperature (about 23° C.). A first portion was allowed to stand overnight and it did not gel visibly within a period of 24 hours but it was observed to gel after a longer period at room temperature, indicating that the solution was supersaturated.
[0096] A second portion within 3 hours of mixing was flowed through a slotted die onto a conveyed aluminum foil 3 mils thick. The aluminum foil had a surface energy of about 45 dynes / cm. The polymer solution had been cooled to about 35° C. and cast at that temperature onto the aluminum foil open to the atmosphere. The wet membrane as cast was about 200-250 microns thick. The acetone and water we...
example 2
[0101] A PVDF polymer solution was prepared and a film was made as in Example 1.
[0102] The dried films were approximately 30 microns thick and were found to have the following characteristics: Gurley number 0.19 seconds (30 microns thick); air permeability 29×104 cm micron / minute Torr; tensile modulus 26,000 psi; tensile yield 2,000 psi; puncture resistance tup with 1 / 16″ radius, membrane clamped 1″ diameter, force to penetrate 81.2 grams / mil thickness, test patterned after ASTM D6241; MacMullin Number 1.15-1.20; and porosity of about 80% as determined by isopropanol absorption.
[0103] FIGS. 3 and 4 show the two surfaces of the films. The surface voids were measured as being: air side average 2.6 microns, standard deviation 1.6 microns; substrate side average 0.8 microns, standard deviation 0.5 microns.
example 3
[0104] A PVDF polymer solution was prepared as in Example 1. The solution was placed in an applicator where it first flowed through a series of mechanical filters to remove any unseen gels, and then was caused to flow through a slotted die onto a conveyed aluminum foil (surface energy about 800 dynes / cm), form-ing a wet film. Room air was caused to flow above the wet film to commence evaporation of the acetone and water, which provided cooling to the film. An opaque matrix was seen within 30 seconds after the wet film was applied, and the conveyor with film then passed through a tunnel oven for about 100 seconds using heated air (at 37° C.) to evaporate the acetone and remove much of the water from the membrane. The membrane was removed by peeling it from the substrate so it could be tested as a free film.
[0105] The resulting films had sufficient strength to be easily handled and the following characteristics: dried films were 20 microns thick, standard deviation 1.3 microns; Gurle...
PUM
Login to View More Abstract
Description
Claims
Application Information
Login to View More