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Acrylian Acrylic Fiber Cross-Section Under the Microscope

Acrylic Fiber, Acrylian

This is a cross-section sample of Acrylian acrylic fiber from the sample-set provided by Textile Fabric Consultants, Inc.

Reflected Brightfield Illumination


Acrylic fiber is derived from petrolium products. It is formed by drawing the polymer in solution through a spinneret into a bath where it solidifies from the outside in. This results in less than a circular cross-section because the outside polymerizes first and is drawn more rapidly though the bath than the interior of the fiber that is still liquid. The draw-rate and process affects the fiber diameter, birefringence, and the cross-sectional shape, from nearly round, to bean shaped, to dog-bone, to slightly crinulate. Acrylic fiber was commertially producted starting in about 1944.

Significance in the Environment:

This is a common clothing fiber.

Characteristic Features:

Acrylic fiber has a refractive index along its length of about 1.50 to 1.53 and perpendicular to its length of about 1.50 to 1.53. It has a birefringence of about 0.002 to 0.012 and a negative sign of elongation. It may exhibit slight irregular striations along its length due to the crinulate cross-section of the fiber, one depression along its length in the case of the dog-bone cross-section, or appear to vary in diameter due to a bean shaped cross-section.

Associated Particles:


DuPont Company Techinical Bulletin X-156: IDENTIFICATION OF FIBERS IN TEXTILE MATERIALS, December 1961.