National Research Council of Canada

Abdellah Ajji

Martin Bureau

Jacques Guevremont

Bentolhoda Heli

Marie Moreno

A mat having a highly uniform porosity distribution is produced by consolidating 15 or more layers of melt blown webs (or the like) having different orientations. Control over the porosity is provided by using webs that exhibit a narrow, unimodal distribution of fiber diameters over the bulk of its distribution, such as in the top 80%. A compliance of the mats can be chosen by selecting a number and orientation of the webs. It is thus possible to produce mats that are good candidates for vascular grafts, for example. The uniformity of the porosity within the range of 6 &#x3bc;m to 30 &#x3bc;m permits seeding of the vascular graft with endothelial and smooth muscle cells. The mats have the demonstrated ability to retain, and support growth of, smooth muscle cells and endothelial cells.

Non-woven mat and method of producing same

A system and apparatus for the measurement of absolute biaxial birefringence of plastic materials is described. The materials which must be at least partially transparent can be constituted of one or several similar or dissimilar layers. In the latter case, the birefringence of each material can be determined. The technique uses a multiwavelength white light source that provides at least two beams projected at different angles of incidence on the sample. The beams pass through first polarizers before they are incident on the sample and through second polarizers after they have passed through the sample. The beams are then directed to a detector for measuring each beam intensity or transmittance as a function of wavelength for the incident angles at different times, and are analyzed using nonlinear regressions to determine retardation. By the knowledge of the thickness of the material, the absolute biaxial birefringences are calculated for any specific wavelength. The regression procedure incorporates the material dependent optical constants for the calculations and to discriminate between different materials for multilayer samples.

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Mount Royal, Canada

Abdellah Ajji