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.
Natural rubber is to be considered as the sole non-synthetic rubber. This particular rubber can be recycled for the reutilization, mostly for the manufacturing of tires. New methods of recycling natural rubber are under development to diminish the ecological impact of used tires and other products. Detaining excellent physical properties (elongation at break, tensile strength and abrasion) and presented in a widespread range of hardness, natural rubber has the best elasticity among all rubbers. Under ambient conditions (a mmix of the right temperature, sun exposition, rain and wind) natural rubbers shows almost perfect fatigue resistance, excellent compression and tear strength which makes it ideal for any dynamic applications.