{"L1_core": {"domain": "material", "category": "polymer", "subcategory": "thermoplastic", "abbreviation": "PC"}, "L5_metadata": {"updated": "2026-01-04", "version": "1.0"}, "L3_standards": {"iso": ["ISO 7391"], "astm": ["ASTM D3935"]}, "L2_properties": {"physical": {"density_g_cm3": [1.20, 1.22], "glass_transition_c": 147, "light_transmission_pct": [88, 90]}, "mechanical": {"impact_resistance": "very-high", "elastic_modulus_gpa": [2.0, 2.4], "tensile_strength_mpa": [55, 75]}, "characteristics": ["impact-resistant", "transparent", "flame-retardant", "dimensional-stable"]}, "L4_applications": ["optics", "safety-covers", "optical-media", "automotive"]}