This technology is available from Temarex Corporation.
Title: MICROCELLULAR FOAMS
Inventor(s): J. R. Elliott Jr., M. Dhanuka, G. Srinivasan, R. Akhaury
Disclosure 172 U. S. Patent 5,128,382
Disclosure 172-DIV U. S. Patent 5,252,620
Supercritical drying has distinct advantages in generating microcellular materials. The dimensional stability of the polymer is not affected on drying because the supercritical process does not go through the two phase path and therefore the effect of capillary forces is absent. This helps in maintaining the morphology of the final polymer structure and better control over cell size.
Organic microcellular foams were prepared by polymerizing directly in a near-critical fluid and pursuing the supercritical drying in the same reactor. The critical variables are the choice of a diluent with a strong enough solvent power to stabilize the polymer matrix, but with a low enough critical temperature to permit critical point drying without damage to the polymer matrix.
This technology competes with both conventional homopolymers and conventional foams. The primary advantage over conventional homopolymers is in reduced density, resulting in lower product weight. The primary advantage over conventional foams is improved strength and durability of the product.
Properties of importance include strength/weight ratio for closed-cell microcellular foams (MCF) is 5 to 6 time greater than macrocellular foams, high pure volume and high surface area of open-celled aerogels, and when cell size _ 0.040 mm the material becomes transparent while retaining their low density and relatively low thermal conductivities.
This technology is suitable for applications such as catalysts supports, membranes or controlled release supports, drug and\or active ingredient delivery system, aerogels for insulation, thermal insulation, structural materials for noise reduction, fusion targets, porous electrodes, filters, adsorbents, high weight/strength applications, and radiation transparent structural materials.