Water absorption HDPE, Polyamide & PET  

Posting by jim on April 17, 2008 at 15:45:56.

I am interested to compare injection moldable polymers, such as HDPE, nylon, PET for instance re. their water absorption rate at different relative humidities and temperatures (btwn 20-40C, 5-100% RH). Is there a reputable reference on the diffusion that is available?

I would be interested in creep values at different stresses and temps, too.

Thanks for your help.


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    On 04/17/2008 Composite Analytica posts: Dear Jim,

    The most reputable reference for absorption figures (diffusion coefficients, water solubility at different degree of humidity, water permeation figures including their Arrhenius energies) is probably still the book of: Cranck J.; Park G.S., Diffusion in Polymers, Academic Press London (1968). This book contains theories that are still significant, handy compilation of key figures (for water absorption we refer to chapter 7) including the references of reputable authors in this area (such as Michaels and Bixler, Cohen and Turnbull etc.)

    In case of interest in more modern polymers, such as polyether etherketone, poly phenylene sulphide, polysulfone, and the effect of filler particles and (fibre) reinforcements this reference is slightly too old.

    Furthermore note that especially in case of absorption of small molecules, such as water and smaller molecules, the degree of crystallinity is of major importance (absorption variations are more than a decade). The books deals with this to a limited extent - at least from a quantitative viewpoint.

    The creep behaviour of high density polyethylene, polyamide 6,6 (nylon) and polyethylene terephtalate, under different stresses, temperature and degree of humidy, can be dealt with by our physical-chemical simulation programmes and our library of experimental key figures. Please do not hesistate to contact us for more information (via form, click on Composite Analytica at the header "Comment by ...." or via j.s.van.der.wal@gmail.com).
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