Focus on Fabrics: Putting Materials to Good Use - Activity

The fibers used in textiles for apparel and home furnishings come from two major sources: natural fibers and synthetic fibers. The natural fibers that come from plants, such as cotton and linen, are generally comfortable and absorbent. Animal fibers, such as wool, silk and mohair, feel soft and luxurious. Spinning the clean original material produces natural fibers.

Synthetic fibers are created through a process that results in a usable fiber. Rayon is made up of regenerated cellulose materials (such as wood pulp and cotton waste). Even though the cellulose material is natural, it is processed with chemicals to create a thick synthetic liquid that can then be spun into a fiber. Other types of synthetic fibers are made from chemicals and are not naturally occurring. Examples include acrylic, nylon, polyester and spandex. These materials are generally easy to care for and resistant to oils and chemicals. Cellulose-based fibers, including acetate and rayon, usually require dry-cleaning.

While we have evidence that some natural fibers were used as long ago as 3,000 to 5,000 BC, synthetic fibers are relatively new inventions. Rayon, the first synthetic fiber, was commercially produced in 1910. Polyester, which is now the most commonly used synthetic fiber in the U.S., was first produced in 1953. New synthetic materials continue to be developed to meet the commercial, industrial and environmental needs of society.

Part I: Testing Synthetic and Natural Fibers.

Divide the class into groups of 2, 3 or 4 students each, depending on materials availability. Have students brainstorm a list of fabrics.
Give each group the following: Worksheet A: Lab Instruction Sheet and the lab materials identified on Worksheet A and Worksheet B: Strength Test Diagram.
Have each group perform the three tests on the fabric samples that are described on Worksheet A. The strength test must be done first. The permeability and absorbency tests are then done on the divided fabric samples.
After the groups have completed the tests, come to a consensus as a class about the results.
Pass out the attached Worksheet C: Characteristics of Fabrics. Have students add the results of their tests to the characteristics already listed.
Lead a discussion on the ways that natural fibers differ from synthetic ones. Ask students whether they think rayon is natural or synthetic. This leads to a discussion of the differences between synthetic fibers from chemicals versus those regenerated from cellulose.

Part II: Choosing a Fabric for an Application

Propose the following design challenge: The Department of Agriculture has proposed that fabrics with seeds embedded in them be used to ensure proper seed spacing. Other advantages of this method include no seed loss to birds, a reduction in soil loss, and reducing weeds in the crops.
Based on their research, have students recommend which material the seeded fabric should be made from. Groups should be prepared to discuss their choices, backing up their decisions with information about the characteristics of the fibers.
Conclude with a class discussion about how students approached the problem like engineers.