Candidate List Duty Triggers in Component Level Imports
Candidate List duties trigger when any discrete component article exceeds 0.1 percent SVHC by weight, regardless of aggregate assembly mass.
Nitrile Butadiene Rubber
Meaning
Synthetic copolymer elastomers formed from acrylonitrile and butadiene monomers provide oil and fuel resistance in dynamic sealing applications. Molded components made from nitrile butadiene rubber function in hydraulic seals and fuel hoses across industrial machinery and automotive engines. Its operating limit is constrained by ozone exposure and elevated temperatures, where uncapped double bonds in the butadiene backbone degrade rapidly.
Acrylonitrile Ratio
Variable acrylonitrile content determines the balance between fuel resistance and low-temperature flexibility in compound formulations. Increasing acrylonitrile percentage in nitrile butadiene rubber enhances resistance to petroleum hydrocarbon fluids while raising glass transition temperature. Lower acrylonitrile content improves low-temperature flexibility but increases swell when exposed to fuels.
Processing Behavior
Viscosity control during compounding ensures proper mold flow during injection moulding or transfer moulding. Formulating raw nitrile butadiene rubber with plasticisers and sulphur or peroxide crosslinking agents establishes vulcanization rates and cavity filling properties. Poor temperature control during molding results in incomplete cure cycles or scorched compound defects.
Solvent Resistance
Swelling resistance in non-polar solvents renders synthetic nitrile compounds suitable for fluid containment systems. Parts moulded from nitrile butadiene rubber retain physical dimensions and mechanical elasticity when submerged in mineral oils. Chemical degradation occurs quickly when parts contact strong polar solvents such as acetone or methyl ethyl ketone.