Kevlar is one material that can be used in chaps. It was one of the popular, early materials used, and people often refer to all the protective fibers in chaps as ‘Kevlar’.Is the primary material in chaps Kevlar?
If you read the technical product descriptions for different brands of chaps, you will find different materials mentioned, although, sometimes they refer to brand names (‘Kevlar’) versus generic names (‘para-aramid fiber’).
But also a variety of other materials. The chaps standards are performance based, not material specific.
STIHL, for example, uses different protective materials in different countries!
For a good ( but geeky) explanation, read the technical blogs posted by Clogger (I wil try to post a link).
Philbert