The Intrinsic Viscosity (IV) is the most vital parameter as it determines the end-use application. For water bottles, an IV of 0.80 ± 0.02 dL/g is standard, while carbonated soft drink (CSD) bottles require a higher IV of 0.84-0.86 dL/g to withstand internal pressure. For industrial yarns or strapping, look for IV levels above 0.90 dL/g. Additionally, monitor the Acetaldehyde (AA) content, which must be <1.0 ppm for water-grade resin to prevent off-flavors, and ensure the melting point is stable between 245°C and 255°C for processing efficiency.