Information on the most widely used ASTM standards within the materials testing industry
ASTM D2137: Standard Test Methods for Rubber Property--Brittleness Point of Flexible Polymers and Coated Fabrics
ASTM D2137 test method is used to evaluate the brittleness of rubber materials, or rubber coated fabrics, when exposed to low-temperature flex with an impact under specified conditions of striker speed. ASTM D2137 tests performed will be used to determine the lowest temperature at which rubber compounds will not show fractures or coating cracks when exposed to specified impact conditions.
Test Principle:
Specimens are mounted as cantilevers in a cooled chamber/bath.
The system is cooled to a target low temperature and held for thermal equilibrium (liquid bath: 5.0 ± 0.5 min; gas chamber: until stable).
A striker impacts all specimens at 2.0 ± 0.2 m/s.

After impact, specimens are bent (90° for A/C/D; 180° for B) and inspected for cracks/fractures.
Testing proceeds at decreasing temperatures until the brittleness temperature is found:
Methods A/B: Lowest temperature with 0 % failure.
Method D: Temperature where 50 % of specimens fail (T₅₀).
ASTM D2137 Test methods:
It defines four distinct test methods for different material types and evaluation goals:
| Method A: | Determines the lowest temperature at which rubber vulcanizates show no fracture/cracking under impact. |
| Method B: | Determines the lowest temperature at which rubber‑coated fabrics show no fracture or coating cracking under impact. |
| Method C: | Performs testing at a specified fixed temperature for material classification and specification compliance. |
| Method D: | Determines the 50 % brittleness temperature (T₅₀), the temperature at which 50 % of specimens fail under impact. |
Testing equipment for the standard ASTM D2137:
The core apparatus is a low‑temperature brittleness tester:
Specimen clamp: Holds specimens as cantilever beams.
Striker: Impact edge radius = 1.6 ± 0.1 mm; impact speed = 2.0 ± 0.2 m/s.
Temperature control system: Cooling (liquid nitrogen or compressor) to reach temperatures typically from −70 °C (-120 °C) to 0 °C.
Recommend UnitedTest UT2064 Rubber Low Temperature Brittleness Impact Tester.
Test Specimens information:
Specimens are die‑cut to standard dimensions:
Method A (Rubber Vulcanizates) Former Type B (Modified T‑50 die) | 25.4 ± 6.4 mm long × 6.35 mm wide × 2.0 ± 0.2 mm thick. | ![]() |
Method B (Coated Fabrics) Fomer Type A | 40 ± 6 mm long × 6.0 ± 0.5 mm wide × 2.0 ± 0.2 mm thick; longer dimension parallel to fabric length. | ![]() |
| Quantity and requirement: | Minimum 5 specimens per test temperature; minimum 16 h between vulcanization and testing. | |
| Conditioning: | 23 ± 2 °C, 50 ± 5 % RH for ≥16 h before testing. |
ASTM D2137 Rubber Brittleness Point Test Test Procedures:
1, Prepare specimens: Die‑cut to standard size; condition.
2, Mount specimens: Secure in the cantilever clamp.
3, Cooling: Lower temperature to a starting point below the expected brittleness point; hold for equilibrium.
4, Impact: Trigger striker to impact all specimens simultaneously.
5, Inspect: Observe the specimen, bend specimens at some conditions and record failures (cracks, breaks, coating delamination).
6, Temperature step:
Methods A/C/D: Use 10 °C steps to locate the failure/no‑failure range; refine with 2 °C steps.
Method B: Test at a specified temperature; 5 specimens with 0 % failure = pass.
7, Calculate/Report:
Methods A/B: Report the brittleness temperature (0 % failure).
Method D: Calculate T₅₀ using the formula:

where T1 = lowest test temp, ΔT = temp step, S = total failed specimens (%).
Relatd Standard:
| ISO 812 | Rubber, vulcanized or thermoplastic--Determination of low‑temperature brittleness (equivalent international standard). |
| ASTM D746 | Brittleness temperature of plastics and elastomers by impact (similar for rigid/flexible plastics). |
| ISO 974 | Plastics--Determination of brittleness temperature by impact. |
| GB/T 15256 | Chinese standard for low‑temperature brittleness of vulcanized rubber (multi‑specimen method). |
| ASTM D1329 | Low‑temperature retraction (TR test) – complementary low‑temperature rubber property test. |
| TCVN 5321 | Rubber, vulcanized or thermoplastic.Determination of low-temperature brittleness. |
| UNE 53541 | Rubber, vulcanized; determination of low-temperature brittleness. |
Importance of the Test for Rubber Materials
Performance prediction: Identifies the critical temperature below which rubber loses flexibility and becomes brittle, preventing catastrophic failure in cold service.
Material selection: Enables comparison of compounds to choose those best suited for low‑temperature applications (e.g., polar regions, cryogenics).
Quality assurance: Ensures consistency in material formulation and manufacturing.
Safety & reliability: Prevents seal/gasket failure in automotive, aerospace, and industrial systems, reducing risks of leaks, malfunctions, and accidents.
Regulatory/compliance: Meets industry and customer specifications for low‑temperature performance.
Related products and device
Related Standard
ISO 812:2017 specifies a method for determining the lowest temperature at which rubber materials do not exhibit brittle failure or the temperature at which half of the test pieces used in a test fail when impacted under specified conditions.
The temperatures thus determined do not necessarily relate to the lowest temperature at which the material can be used since the brittleness will be affected by the conditions of test and especially by the rate of impact. Data obtained by this method are, therefore, intended to be used to predict the behaviour of rubbers at low temperatures only in applications in which the conditions of deformation are similar to those specified in the test.
ASTM D746: Standard Test Method for Brittleness Temperature of Plastics and Elastomers by Impact
ASTM D746 test method establishes the temperature at which 50 % of the specimens tested would probably fail when subjected to the conditions specified herein. The test provides for the evaluation of long-time effects such as crystallization, or those effects that are introduced by low-temperature incompatibility of plasticizers in the material under test. Plastics and elastomers are used in many applications requiring low-temperature flexing with or without impact. Use data obtained by this method to predict the behavior of plastic and elastomeric materials at low temperatures only in applications in which the conditions of deformation are similar to those specified in this test method. This test method has been found useful for specification purposes, but does not necessarily measure the lowest temperature at which the material is suitable for use.
ISO 974 Plastics -- Determination of the brittleness temperature by impact
Scope:
Brittleness temperature is the temperature at which 50% of the tested specimens exhibit brittle failure at specified impact conditions. It is utilized primarily for plastics and elastomers.
Test Procedure:
Specimens are secured in the customer specified specimen holder (A or B) with a torque wrench at 5 in-lb. The specimen holder is lowered into a bath at a specified temperature. The specimens are impacted at 2000 ± 200 mm/s and then examined. The procedure is repeated at a lower temperature until enough data is generated to determine a brittleness temperature. Brittle temperature is the temperature at which 50% of the specimens fail. Brittle failure is defined by ASTM D746 as fracture into 2 or more pieces, or any crack visible to the unaided eye. The specimens can be bent to an angle of 90° and examined for cracks at the bend.
FAQs: ASTM D2137 Rubber Brittleness Point Test
Q1: What is ASTM D2137 mainly used for?
A: ASTM D2137 standardizes the test method to determine the low-temperature brittleness temperature of vulcanized rubbers, flexible polymers, and rubber-coated fabrics. It measures the critical temperature below which the material becomes brittle and fractures under impact.
Q2: What’s the difference between brittleness temperature and glass transition temperature (Tg)?
A:Brittleness temperature (from D2137): A practical performance value under impact at low temperature.
Tg (glass transition): A fundamental thermal property from DSC or DMA.
They are related but not identical. D2137 reflects real-world impact behavior at low temperature, which is more meaningful for engineering applications.
Q3: How is failure defined in D2137?
A: Failure includes:
Complete fracture
Visible cracks after bending
Coating cracking or delamination (for coated fabrics).
Q4: Can I use the same specimen for D2137 and other low-temperature tests?
A: Usually not. Each standard has its own geometry, thickness, impact speed, and failure criteria. Specimens must be prepared specifically for ASTM D2137.
Q5: Why do different labs sometimes get slightly different brittleness temperatures?
A: Differences come from:
Equipment calibration
Temperature uniformity
Specimen preparation
Operator judgment of cracking
Test speed and impact alignment
Strictly following D2137 procedures minimizes variation.
Q6: How does D2137 help in product design?
A:Tells designers the lowest temperature at which the material remains tough.
Prevents product failure in winter, high altitudes, or cold storage.
Supports material certification and customer specifications.
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