DSC — ISO 11357 / ASTM D3418 / ASTM E1356 · Plastics Testing

What Is DSC?

DSC analysis is an analysis method in which thermal events such as melting, crystallization, glass transition and reaction heat are determined by measuring the heat flow difference between the sample and the reference against the temperature.

Purpose of DSC

The goal is to verify the material identity and process history of the polymer by determining its glass transition and melting temperatures, degree of crystallinity, and cure state.

Which Products Is DSC Applied To?

Thermoplastic and thermoset polymers
Composite resins and prepregs
Adhesives and coatings
Pharmaceutical and food solids

In Which Sectors Is DSC Used?

PlasticsAutomotivePackagingConsumer Products

Standards Related to DSC

ISO 11357 serisi
ASTM D3418
ASTM E1356
ASTM E793

DSC Conditions

Temperature program: Heating–cooling–second heating; speed defined in standard or specification (typical 10 °C/min)
Atmosfer: Inert (nitrogen) or oxidizing; should be stated
sample mass: Defined in the standard; typically a few milligrams
Calibration: Temperature and heat flow calibration with certified reference materials

Equipment for DSC

Differential scanning calorimeter
Sample encapsulation press and capsules
Cooling unit (mechanical or liquid nitrogen)
Certified calibration standards (e.g. indium)

Sample Requirements for DSC

The sample must be representative and homogeneous
The sample should be placed in good contact with the capsule.
The process history is visible on the first heating; The second heating gives the material its property
The mass must be weighed correctly

Duration of DSC

Typically 2–4 days.

DSC Procedure

1The device is calibrated with the reference substance.
2The sample is weighed and encapsulated.
3The temperature program is applied.
4The heat flow curve is recorded.
5Transition temperatures and enthalpies are evaluated.
6The results are interpreted.

DSC Acceptance Criteria

Acceptance criteria are transition temperatures or cure degree limits defined in the specification.

Evaluation of Results

The first heating curve carries the processing and storage history of the material; Second heating is used for material property. The heating rate shifts the transition temperatures, so comparison cannot be made without reporting the rate.

DSC Report

Standard applied
Temperature program and atmosphere
Sample mass and capsule type
Calibration records
Transition temperatures and enthalpy values

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Material product standards and cure specifications

Plastics Testing — What Does This Testing Field Cover?

The section below describes the field that the DSC test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Plastics testing determines the mechanical, thermal and burning behaviour of a polymer material. Unlike metals, plastics are VISCOELASTIC: their behaviour depends on loading rate, temperature and moisture. The same material therefore gives different results under different conditions, and the test conditions are an inseparable part of the result.

The practical consequence of viscoelasticity is this: a plastic part continues to deform over time under a constant load (creep) and the stress it carries at constant deformation falls over time (stress relaxation). A screwed joint loosens, a clamp loses its clamping force, a shelf sags over time. A short-term tensile test does not show this behaviour; a long-term test or an accelerated model is needed.

Thermal behaviour is the second main axis. Melt flow rate indicates the processability of the material and lot-to-lot consistency; heat deflection temperature and the Vicat softening point give a rough limit for service temperature. Thermal analysis (DSC, TGA, DMA) reveals the identity of the material: glass transition temperature, melting behaviour, crystallinity, filler content and decomposition temperature.

Burning behaviour is the third axis and ties directly into product standards. The UL 94 class and the limiting oxygen index are written into the material data sheet; a particular class is required for the housing of an electrical appliance, while a different classification system applies to a construction product.

Ageing is the most frequently skipped part of the field. Plastics degrade under UV, heat, moisture and oxygen: colour changes, the surface cracks, impact strength falls. For a part intended for outdoor use, what matters is not its values on day one but its values after ageing. Xenon arc and fluorescent UV equipment accelerate this degradation and allow comparison.

The output of this family is usually written into the material data sheet, and product standards refer to that sheet. But there can be a difference between the data sheet value and the behaviour of the actual part: orientation formed during moulding, weld lines and internal stresses make the part behave differently from the specimen.

The use of recycled content has added a new question to the field. Recycled resin varies from lot to lot; mechanical properties, colour and burning behaviour can shift between batches. For a manufacturer using recycled material, incoming material control is therefore not a choice but a necessity.

Method groups in this field

Mechanical
Tension, compression, bending, Charpy and Izod impact, hardness (Shore), creep and environmental stress cracking.
Thermal
Melt flow index (MFI), heat deflection temperature (HDT), Vicat softening temperature, linear thermal expansion.
Thermal analysis
Transition temperatures and crystallinity by DSC, composition and decomposition by TGA, dynamic mechanical behaviour by DMA.
Burning
UL 94 classification, limiting oxygen index (LOI), glow wire and needle flame tests.
Ageing
Accelerated ageing by xenon arc and fluorescent UV, hot air ageing, humidity and condensation.
Physical
Density, water absorption, ash content, gas and water vapour permeability of films and sheets.

Commonly confused in this field

A plastics result without a stated test rate and temperature cannot be interpreted; viscoelastic behaviour depends on these parameters.
A specimen result does not transfer directly to the actual part; moulding orientation and weld lines are decisive.
HDT and Vicat values are NOT service temperatures; they are a rough indication of an upper limit and do not apply under load.
The UL 94 class depends on thickness; a different wall thickness requires re-verification.
For moisture-absorbing polymers (such as polyamide), results are misleading unless conditioning is carried out.
ASTM D638 and ISO 527 results are not directly equivalent; the specimen geometries and rate definitions differ.

Which decisions these results support

Material selection and supplier approval
Meeting the flammability and thermal requirements of the product standard
Verifying the use of recycled content and lot control
Moulding process control and lot consistency
Demonstrating ageing resistance for outdoor use

Related Tests

Frequently Asked Questions About DSC

According to which standard is DSC made?

DSC is executed in scope ISO 11357 serisi, ASTM D3418, ASTM E1356 and ASTM E793. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.

Which products does DSC apply to?

Mainly applied to Thermoplastic and thermoset polymers, Composite resins and prepregs, Adhesives and coatings and Pharmaceutical and food solids. Whether your product is included in the scope is determined by examining its technical specifications and intended use.

Under what conditions is DSC done?

The determining parameters are: Temperature program — Heating–cooling–second heating; speed defined in standard or specification (typical 10 °C/min), Atmosfer — Inert (nitrogen) or oxidizing; should be stated and sample mass — Defined in the standard; typically a few milligrams. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.

What kind of sample is needed for DSC?

The sample must be representative and homogeneous, The sample should be placed in good contact with the capsule. and The process history is visible on the first heating; The second heating gives the material its property. The number of samples is determined according to the product standard and the scope to be reported.

How long does DSC take?

Typically 2–4 days. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.

What is the DSC result called "appropriate"?

Acceptance criteria are transition temperatures or cure degree limits defined in the specification.