Tuesday, 4/14/15• Objectives: Support the identification of your

unknown fiber with evidence from your tests. Evaluate your group’s performance on the lab.

• Agenda: – Review natural vs. manmade fibers– Whiteboard/discuss your evidence for the identity of your

unknown fiber sample– Lab reflection

BELLRINGER: As a group, respond to the following on your whiteboard:1. Which 3 of the 6 known fibers do you think were

manmade? (Look at the test results, not just prior knowledge!

2. Support your choices with evidence from the lab.

Natural vs. Manmade FibersNatural Manmade

Origin Entirely plant or animal based, not chemically treated to reorganize polymers

Either consists of fibers that have been chemically treated to restructure their polymers or are composed entirely of chemicals

Burn residue Will usually form ash Will typically melt

Smell when burned Hair or paper-like smell Chemical smell

Appearance of fibers Lengths vary, twisting/kinks common and in sometimes inconsistent patterns, cuticle/medulla sometimes present

Length/widths constant, may show striations down the length of the fiber

Stain Test Usually absorbs a lot of dye Usually absorbs less dye

Using this information, can your add additional support to your identification of the manmade and natural fibers?

Fiber Identification Lab

• Acetate• Wool• Nylon 6.6• Silk• Viscose• Cotton

Manmade

NaturalManmade

Manmade

Natural

Natural

Fiber Identification Lab - Conclusion1. Write the # of your unknown on the top of your white

board.2. Write the results for each test you performed on the

unknown.3. Analyze your data and draw a conclusion:

– State what fiber your unknown was and support this conclusion with evidence from your results

– Explain which test(s) was(were) the most helpful in identifying your fiber.

• Be prepared to present your findings to the class. You are expected to compare your unknown to each of the knowns – it is suggested you script this on a sheet of paper.

You have 10 min.

Lab Discussion

• Each group will have ~2min to present their results and explain how they reached their identification

• The audience is expected to ask the group questions about their conclusions.

• Group reflection – due at the end of the period– Work efficiently!