Plastics. Polypropylene (PP) moulding & extrusion materials. Designation system & basis for specifications Plastics, Polymers, Polypropylene, Thermoplastic polymers, Moulding (process), Moulded materials, Extruding, Designations, Modulus of elasticity, Tensile stress, Tensile strain, Impact strength, Viscosity, Weight (mass)