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.
Flame Retardants
Meaning
Chemical additives suppress ignition and slow flame propagation in flammable polymer matrices during thermal exposure. Specially formulated flame retardants are compounded into engineering resins such as polycarbonate and polyamide to satisfy strict flammability standards for electrical enclosures and automotive components. The protection boundary depends on additive loading levels and chemical structure, beyond which excessive additive concentration degrades mechanical integrity and melt stability.
Combustion Mechanism
Gas-phase radical scavenging and condensed-phase char formation prevent sustained combustion in burning plastics. Incorporating active flame retardants forms protective carbonaceous barriers that insulate underlying resin from radiant heat and oxygen exposure. Synergistic mineral fillers like aluminum trihydrate release water vapor upon heating, cooling the melt zone and diluting flammable pyrolysis gases.
Property Degradation
High additive loading rates alter resin toughness and impact resistance. Compounding structural resins with unreactive flame retardants reduces tensile strength and increases compound density compared to neat resin grades. Mould design must account for altered shrink rates and weld line strength reductions caused by high filler loads.
Processing Stability
Thermal stability determines the processing window during injection moulding operations. Temperature drift can cause flame retardants to decompose, releasing corrosive gases that etch mold cavities. Molders monitor melt temperature to prevent additive breakdown.