Overview
ISO 11357-7:2022 - Plastics - Differential scanning calorimetry (DSC) - Part 7: Determination of crystallization kinetics defines standardized DSC procedures for studying the crystallization kinetics of partially crystalline polymers. The standard specifies two complementary approaches: isothermal and non‑isothermal DSC methods. It applies only to molten polymers and is not suitable when the polymer molecular structure is altered during the test.
Keywords: ISO 11357-7:2022, differential scanning calorimetry, DSC, crystallization kinetics, plastics, polymers, isothermal, non-isothermal, thermal analysis
Key topics and technical requirements
- Scope and applicability: Methods for kinetic analysis of molten, partially crystalline polymers; excludes tests that modify polymer molecular structure.
- Methods:
- Isothermal crystallization: rapid cooling to a set temperature, measure relative crystallinity α(t) over time.
- Non‑isothermal crystallization: cooling at a constant rate and measuring α(T) versus temperature.
- Apparatus & materials: DSC instrument and crucibles per ISO 11357-1; balance and purge gas per ISO 11357-1. Verify crucible material does not affect kinetics.
- Specimen preparation: Follow ISO 11357-1; choose specimen mass to avoid self‑heating (when comparing grades, maintain mass within ±0.5 mg).
- Melting protocol: Typically heat at 10 K/min or 20 K/min to about 30 K above extrapolated end‑melting temperature and hold 3–5 min (optimize to avoid altering molecular structure).
- Calibration & temperature symmetry: Calibrate heating mode per ISO 11357-1 and check symmetry of temperature scale (heating vs cooling) using substances with low, defined undercooling.
- Test design: Perform at least three runs at different isothermal temperatures or cooling rates. Cooling rates must be within instrument capabilities and linearity.
- Results & output: Determine relative crystallinity α (partial enthalpy/total enthalpy ΔHc) and report parameters such as ti (initial crystallization time), tmax, t0.5, tf (isothermal) and Ti, Tpc, T0.5, Tf (non‑isothermal). Use literature models (Annex A) for kinetic analysis. Note: interlaboratory precision data are not available.
Applications and users
- Practical for laboratories and R&D teams performing polymer thermal analysis, formulation optimization, crystallization rate comparisons, and process development (injection molding, extrusion, annealing).
- Useful to materials scientists, polymer chemists, quality control engineers and instrument manufacturers needing reproducible DSC protocols for comparing polymer grades and studying processing‑related crystallization behavior.
Related standards
- ISO 11357-1: General principles for DSC (calibration, apparatus)
- ISO 11357-3: Determination of melting and crystallization temperatures and enthalpies
- ISO 472: Plastics - Vocabulary
Use ISO 11357-7:2022 when you need standardized, reproducible DSC methods to quantify polymer crystallization kinetics for research, quality assessment, and process optimization.