Distortion temperature dosage (DTD)

Heat deflection temperature ( HDT ) is a standard thermal analysis used to evaluate a polymer material's resistance to deformation under a constant mechanical load. This test is particularly useful in the plastics, composites, and bio-based materials industries to predict their behavior at high temperatures, especially under demanding service conditions.

ISO 75 / ASTM D648 standard method: a rigorous and recognized protocol

The distortion temperature measurement is performed according to international standards ISO 75 or ASTM D648. The test principle consists of applying a constant load to a standardized polymer sample, then gradually increasing the temperature until the deflection reaches a defined value. The temperature at which this deformation is reached constitutes the distortion temperature.

According to the standards, several stress levels (e.g., 0.45 MPa, 1.8 MPa) can be applied to simulate different industrial use cases. This test provides critical information for material selection in thermomechanical applications.

Why measure the distortion temperature (HDT)?

The heat transfer coefficient (HDT) is a key thermal performance criterion in many industrial sectors. It enables:

• To compare different grades of polymers in terms of temperature resistance
• To guide the selection of materials for parts subjected to heat and mechanical stress (casings, covers, technical components, etc.)
• To validate formulations based on modified polymers or reinforcing fillers
• To evaluate the performance of bio-based materials compared to petroleum-based benchmarks
• To support a technical file (technical data sheet, declaration of conformity, customer specifications)

Relevant matrices and application sectors

The HDT test applies to a wide range of thermoplastic and thermosetting materials:

• Standard plastics (PE, PP, PS, PVC…)
• Engineering polymers (PA, PBT, PC, PEEK, etc.)
• Thermosetting resins (epoxy, polyester, phenolic)
• Reinforced composites (fiberglass, carbon fiber)
• Bio-based or biodegradable materials
• Samples derived from recycling or experimental formulations

This test is used in many industrial sectors:

• Packaging: to guarantee dimensional stability when hot (films, containers, lids, etc.)
• Automotive and transport: material selection for under-hood parts or interior components
• Electrical/electronic components subjected to heating or thermal cycles
• Construction: insulation, piping, joinery made of polymer materials
• Research & development: formulation improvement, material substitution

Specialized laboratories for controlled testing

YesWeLab relies on a network of partner laboratories specializing in the mechanical and thermal analysis of materials. All have calibrated equipment and procedures compliant with ISO 75 or ASTM D648 standards. We direct your request to the most appropriate laboratory based on:

• The type of material to test
• The specific mechanical constraints to be applied
• Normative or contractual requirements
• The desired delivery times and format of the results

Tailored support for your materials projects

Thanks to our digital platform, you can submit your request online, select your services, track the progress of the tests, and securely retrieve the results. Our scientific team also provides upstream advice to help you choose the right test parameters, optimize sample preparation, and interpret the results.

Further analyses recommended

For a complete characterization of your materials, consider combining the HDT test with other services:

• DSC analysis – Glass transition temperature (Tg)
• TGA Analysis – Thermal Stability
• Tensile and flexural tests

Get your quote now

Add this service to your quote request or contact our team to discuss your needs. YesWeLab has been supporting materials and polymer manufacturers since 2020, with an approach focused on quality, compliance, and responsiveness. Whether for quality control, product development, or technical expertise, we are here to help.