{"L1_core": {"domain": "material", "category": "polymer", "variants": ["HDPE", "LDPE", "LLDPE"], "subcategory": "thermoplastic", "abbreviation": "PE"}, "L5_metadata": {"updated": "2026-01-04", "version": "1.0"}, "L3_standards": {"iso": ["ISO 1872"], "astm": ["ASTM D1248"]}, "L2_properties": {"physical": {"density_g_cm3": [0.91, 0.97], "melting_point_c": [105, 135]}, "mechanical": {"elastic_modulus_gpa": [0.2, 1.4], "tensile_strength_mpa": [8, 32]}, "characteristics": ["chemical-resistant", "flexible", "moisture-barrier", "recyclable"]}, "L4_applications": ["bags-films", "piping", "bottles", "cable-insulation"]}