{"L1_core": {"domain": "material", "category": "polymer", "variants": ["PA6", "PA66", "PA12"], "subcategory": "thermoplastic", "abbreviation": "PA", "chemical_name": "polyamide"}, "L5_metadata": {"updated": "2026-01-04", "version": "1.0"}, "L3_standards": {"iso": ["ISO 1874"], "astm": ["ASTM D4066"]}, "L2_properties": {"physical": {"density_g_cm3": [1.02, 1.15], "melting_point_c": [220, 265], "water_absorption_pct": [1.5, 3.5]}, "mechanical": {"elastic_modulus_gpa": [1.0, 3.5], "tensile_strength_mpa": [40, 85]}, "characteristics": ["wear-resistant", "self-lubricating", "tough", "hygroscopic"]}, "L4_applications": ["gears-bearings", "technical-textiles", "mechanical-parts", "cable-ties"]}