Ray-Ran Environmental Stress Cracking Apparatus

Testing environmental stress cracking

Our Environmental Stress Cracking Apparatus determines the susceptibility of ethylene plastics to stress cracking when exposed to different environments such as soaps, wetting agents, oils, acids, and detergents.  

Test samples are subjected to a predetermined bending stress and then exposed to different environments to see if they exhibit any mechanical defects by cracking, perfect for testing samples before production or final design processes.  

Environmental stress cracking explained 

When the material is under certain conditions of stress, environmental reagents such as soaps, wetting agents, detergents, and acids can accelerate the cracking process which is one of the most common causes of unexpected brittle failure of polymers known. Designed in accordance with ASTM D1693, the apparatus is extremely cost-effective and very simple to use.  

How to conduct an environmental stress cracking test 

1. Cut the sample material to the required shape and introduce a controlled notch defect using the nicking jig supplied with equipment. 
2. An induced stress is made on the sample through bending and it is placed into the test sample rack and moved to the test tube. 
3. The tube is filled with the test reagent before being placed into the test bath at a constant temperature.  
4. At timed intervals, the samples are checked for any cracks developing at 90° to the notch.  
5. The number of failures is recorded. 

Controlled stress cracking apparatus testing

The apparatus is supplied with electronic digital temperature control, temperature bath, and all tooling accessories to ensure a convenient testing process.  

• The integrated temperature bath is fitted with a digital temperature controller, heater and thermometer that accurately maintain the test temperature, usually 50°C or 100°C± 0.5°C.  
• To ensure temperature stability within the bath, a stirrer motor system is fitted, and the built-in electronic timer monitors the duration of the test.  
• The bath is fitted with a stainless-steel sample rack that holds up to 48 glass test tubes which are immersed in a heat transfer medium such as silicone oil.  

• Rubber stoppers to seal the tubes and test sample specimen holders in either brass or stainless steel (optional) are also supplied for each tube.
• The specimen holder is designed to maintain a constant stress on the mid-section of the test samples with up to 10 specimens fitted into a specimen holder at one time.  

Tooling accessories

Tooling accessories for our environmental stress cracking testing instrument include: 

• Sample Cutter – 38 mm x 13 mm. 
• Sample Nicking Jig – Used to make a controlled imperfection in the test sample. 
• Sample Bending Clamp – Used to induce concentrated stress in the sample. 
• Sample Transfer Tool – Used to move test samples from the bending clamp into the specimen holders. 

Meeting environmental stress checking standards

It’s important that when you’re carrying out environmental stress cracking testing, you know whether you’re meeting international standards. That’s why this apparatus is compliant with ASTM D1693, the standard test method for evaluating the Environmental Stress Cracking Resistance (ESCR) of Ethylene plastics, by chemical immersion of pre-stressed specimens at elevated temperatures.