Kevlar
Kevlar is the trademarked name for a brand of light, strong para-aramid synthetic fiber.
Similar to Nomex, Kevlar has a high strength-to-weight ratio and is resistant to high temperatures.
Kevlar is used in rocketry in several ways.
Kevlar thread is used in place of elastic materials as shock cords for model rockets or as shroud lines for parachutes.
In larger rockets, tubular Kevlar is used as shock cords or as a sleeve to protect a shock cord. And Kevlar sheets are used to protect parachutes from the heat and burning particles of the ejection charge.
Large Kevlar sleeves, known as "socks," are sometimes used in place of fiberglass to reinforce a body tube. Kevlar fabric is sometimes used to create composite fins.
References: