{"L1_core": {"domain": "material", "category": "polymer", "variants": ["rigid-uPVC", "flexible-PVC"], "subcategory": "thermoplastic", "abbreviation": "PVC", "chemical_name": "polyvinyl chloride"}, "L5_metadata": {"updated": "2026-01-04", "version": "1.0"}, "L3_standards": {"iso": ["ISO 1163", "ISO 1452"], "astm": ["ASTM D1784"]}, "L2_properties": {"physical": {"density_g_cm3": [1.30, 1.45], "max_service_temp_c": [60, 80]}, "mechanical": {"elastic_modulus_gpa": [2.4, 4.1], "tensile_strength_mpa": [40, 60]}, "characteristics": ["flame-retardant", "chemical-resistant", "weatherable", "low-cost"]}, "L4_applications": ["piping", "window-profiles", "electrical-cables", "packaging"]}