Polyamide is a synthetic fiber formed of linear macromolecules having in the chain the recurring amide functional group. There are polyamides of low affinity and high affinity. They have low flammability, it starts to weaken at 180-200 ° C and melts at about 215-260 ° C. Good elasticity (greater than typical polyester). The polyamide yarn can have the strength of steel and fine wire of the spider. Depending on the weaving, the fabric may exhibit a very close silk appearance. Polyamide fabrics are often in the name of nylon which designated the base polyamide 6-6 whose current usage returns to generically polyamides.
Butyl, also known as Isobutylene-isoprene (IIR), is a synthetic rubber developed in the 1940’s. It has exceptionally low gas permeability making it ideal for inner tubes and high pressure/vacuum sealing applications. Its very low resilience makes it suitable for shock and vibration damping. Its chemical unsaturation gives it excellent resistance to heat, ozone, and weathering, and also to dilute acids and alkalis.
It is not suitable for use in mineral or petroleum based fluids.