Overview
ISO 4216:2021 specifies a continuous measurement method for determining shrinkage of thermosetting resin and UV curable resin during curing. The standard defines the principle, apparatus, test conditions and measurement procedure to record thickness change over time and calculate volumetric / curing shrinkage for small samples. This method enables high-accuracy shrinkage measurement using trace amounts of resin and provides continuous data on curing behavior (thermal expansion, contraction and reaction shrinkage).
Key topics and technical requirements
- Principle: Shrinkage is derived from continuous measurement of sample thickness in a container with fixed cross-sectional area. Shrinkage (%) = (T1 − T2) / T1 × 100, where T1 is initial thickness and T2 thickness at an arbitrary time.
- Test conditions: Default laboratory atmosphere is 23 °C ± 2 °C and 50 % ± 5 % relative humidity unless otherwise specified.
- Number of measurements: At least three samples per curing condition.
- Apparatus components:
- Sample container: known volume/dimensions; typical depth 0.5–3 mm and inner diameter 10–15 mm; smooth bottom, cylindrical to keep cross-sectional area constant.
- Displacement gauge (thickness meter): non-contact (e.g., laser or interferometric); resolution must be better than 1/10 of expected thickness change.
- UV irradiation device: uniform wavelength selection and sufficient illuminance for complete curing.
- Heating/cooling device: control stage temperature within ±3 °C from setting; capable of reaching curing temperatures (e.g., epoxy applications may require up to ~150 °C).
- Data processing unit: capture interval and processing speed compatible with the resin curing rate to record shrinkage over time.
- Curing methods: three categories - UV curing, thermal curing, and combined UV + thermal curing. Parameters (irradiation intensity, temperature program, heating/cooling rate) must be predefined.
- Results and reporting: Clause 10 defines volumetric and curing shrinkage expressions; Annexes provide influencing factors, example results and report format.
Applications and users
- Applications: quality control and R&D for epoxy encapsulants, adhesives, coatings, electronic device resin coatings, and other high-precision resin applications where dimensional stability and curing performance matter.
- Who uses it: materials scientists, plastics and polymer test laboratories, electronics manufacturers, resin formulators, quality assurance engineers and certification labs requiring repeatable, high-resolution shrinkage measurement.
Related standards
- Normative reference: ISO 472 (Plastics - Vocabulary) is cited for terms and definitions used in ISO 4216:2021.
Keywords: ISO 4216, thermosetting resin, UV curable resin, shrinkage measurement, continuous measurement method, curing shrinkage, volumetric shrinkage, displacement gauge.