ISO 17744:2025 pdf download,Plastics — Determination of specific volume as a function of temperature and pressure, pvT diagram — Piston apparatus method.
ISO 17744:2025 describes how to determine the specific volume of plastics as a function of temperature and pressure, producing a pvT diagram. It gives standardized procedures for measuring both molten and solid-state material behavior using a piston-equipped apparatus. The plastic specimen is placed in a measurement cell and compressed by applying controlled pressure with the piston. Measurements can be performed under constant-pressure or constant-temperature conditions, with constraints on heating/cooling rates to ensure stable, comparable data. The standard explains how to use the collected pressure–temperature–volume data to obtain relationships between pressure, specific volume, and temperature for a given plastic. From these measurements, users can derive volumetric compressibility and volumetric thermal expansion coefficients, and extract information related to first-order transitions and glass transition behavior as functions of temperature and pressure. The resulting pvT data support material characterization and process design decisions.
