The technicalities: Origins
Acrylic fibers are derived from acrylonitrile, a petrochemical. The fiber was developed to imitate wool and is often used as a wool substitute. During the production of acrylic, the acrylonitrile is first polymerized to produce a polyacrylonitrile resin, which is then spun into fibers.
Polyester fibers are made from polyethylene terephthalate (PET), another petrochemical. The polyester production process involves melting the PET and extruding it through small holes, where it solidifies and is then cut or spun into fibers.
What is the difference?
Acrylic texture is often softer than polyester, with a wool-like feel. It’s a good insulator and often used in sweaters and blankets. Less durable than polyester. Acrylic tends to be less breathable and can trap moisture.
Polyester generally has a smoother feel that can be sensed as “softer” in shorter piles, but its texture can be modified in various ways. Provides insulation, and its moisture-wicking properties can make it feel less warm in comparison to acrylic. Known for its strength and longevity, it dries quickly and doesn’t retain moisture like natural fibers.
Our take:
Acrylic and polyester are both similar in origin, and while chemically different have very similar issues related to sustainability and origins. The problem with polyester is that it doesn't decompose, hence is unsustainable, along with some other claims that it is carcinogenic. Acrylic has similar origins and similar fears associated with it's development.