Overview
EN ISO 75-2:2013 - "Plastics - Determination of temperature of deflection under load - Part 2: Plastics and ebonite" is the CEN-adopted version of ISO 75-2:2013. It specifies laboratory methods to determine the temperature of deflection under load (commonly called heat deflection temperature or HDT) for plastics (including filled and short-fibre reinforced plastics with fibre length ≤ 7.5 mm) and ebonite. The standard defines test conditions, specimen requirements and measurement procedures for three constant flexural stress levels.
Key topics and technical requirements
- Three test methods (constant flexural stress):
- Method A: 1.80 MPa
- Method B: 0.45 MPa
- Method C: 8.00 MPa
- Test geometry and span: The recommended support span is 64 ± 1 mm. Common specimen format used in the standard is 80 mm × 10 mm (thickness as specified in the table within the standard).
- Heating and equipment: Heating methods follow ISO 75‑1 (general methods). Modern accepted heat-transfer techniques include oil baths, air ovens and fluidized‑bed systems - fluidized-bed/air ovens are noted for high-temperature stability.
- Measurement principle: A constant flexural stress is applied and the temperature at which the specimen’s deflection reaches a specified (standard) deflection is recorded as the temperature of deflection under load.
- Material considerations: Better reproducibility is typically achieved with amorphous plastics than semi-crystalline ones. Annealing of specimens may be required to reduce variability caused by moulding conditions.
- Quality control: The standard defines repeat-testing rules when individual results exceed the reproducibility limits given in the document.
Practical applications
- Material selection and specification: compare temperature performance of candidate plastics and ebonite under load.
- Quality assurance and batch validation: verify that production materials meet specified thermal-mechanical performance.
- Design verification: assess suitability of housings, structural components, and load-bearing parts exposed to elevated temperatures.
- Supplier compliance and procurement: include EN ISO 75-2:2013 test data in technical datasheets and procurement specifications.
Who uses this standard
- Materials and polymer engineers
- Test laboratories and QA departments
- Product designers and R&D teams
- Plastics compounders, moulders and manufacturers of ebonite products
- Regulatory and compliance teams specifying thermal performance
Related standards
- ISO 75-1 - General test method for determination of temperature of deflection under load (heating methods and general principles)
- ISO standards for specimen preparation and moulding (referenced within EN ISO 75-2)
Keywords: EN ISO 75-2:2013, temperature of deflection under load, heat deflection temperature, plastics and ebonite, flexural stress, HDT, material testing, ISO 75-1.