Hi Ivanna

How many days depends on the thickness of your sample. I've conditioned for 7 days with samples of 3 to 5 mm thickness.

Hi Marc Simonet ,

Thanks for your response. I have 2 mm thickness samples, but I know that under Accelerated conditioning we need 7 days, so standard conditioning should take a bit longer time. Right?

Hi Ivanna

You are correct should be longer , my apologies I gave you a "how I've done it in industry" rather than scientific sound answer.

At norm-climate we conditioned for 7 days but that does not mean the samples are fully conditioned. The 7 days are an economical and SOP/ISO driven decision.

Regards

Marc

Dear Ivanna,

Because in the past I was concerned by the subject “polyamides”, I followed with interest your question. I must to recognize that it is difficult to find the best information, since it is needed to take in consideration the thickness of samples and conditioning method, i.e. the procedure that is applied, see ISO 1110 or ISO 68).

PA 12 has low absorption of water at equilibrium when is maintained at 23°C/50%HR, i.e. about 0.7%, and about 1.5% at saturation- when is immersed in water (https://almkompaundi.rs/wp-content/uploads/2018/08/Water-Absorption-and-Conditioning-LANXESS.pdf;

https://www.vestamid.com/sites/lists/re/documentshp/vestamid-l-compounds-en.pdf).

According to ISO 1110 for specimens of 2 mm thickness it will be required a conditioning time of at least 1.5 days or 4 days (accelerated conditioning using “cabinet” or “container” method, respectively). Let’s go to give some credit to these methods as preliminary information!

However, if you will not like to use accelerated conditioning, practically there is the variant to try directly to determine the conditioning time at 23 °C / 50% relative humidity by following as objective the number of days to arrive to constant weight (see also ISO 68). This approach is applied by some producers of PA 12.

Finally, function of your goals, please consider that in some standards is given some formal/general recommendation about the time for the conditioning of specimens:

e.g., D 638 Standard Test Method for Tensile Properties of Plastics

Conditioning—Condition the test specimens at 23 ±2°C and 50 ± 5 % relative humidity for not less than 40 h….

Good luck in your research studies and best regards,

Marius