Synthetic fibres, Polyamide fibres, Aramide fibres, Textile products, Textile testing, Yarn, Filament yarns, Filaments, Filament (Textile fibre), Yarn testing, Yarn linear density determination, Elongation at fracture, Elongation, Force measurement, Mechanical testing, Modulus of elasticity, Twist determination (textiles), the Test specimens, Specimen preparation, testing the conditions, the Test atmospheres, Test equipment, Equations