It seems to me that the chutes that we used to buy at the surplus store in the late 40s and used for tarps were made of nylon.
Didn’t pay that much attention since their material content wasn’t of any importance.
By the time I bought any parachute material, it was camoflaged, nylon, and Vietnam era. (We used it to make deer stands, cut into strips about 4 ft. wide and wrapped around available brush or three/four stakes. It was easy to carry, and worked pretty well.)