Chemical Resistance of FRP Pipe against Glycerol  

Thread by Hein van de Vegt on 29 Apr 2009 at 18:00:49 
Dear All:

Is glass fibre reinforced (Vinyl Ester) Epoxy and/or Polyester resin chemical resistant to Glycerol (Glycerol being conveyed in a pipe at ambient conditions: slight overpressure, temperature in the range of +5 to +60 degrees Celsius).

Further to the information on this forum and website, I have some serious doubts on the use of comonly used FRP for Glycerol due to diffusion and swelling phenomena. Can the pipe collapse due to extensive swelling? What are other expected (corrosion / chemical resistance) failure modes or defects of such a piping system?

Thanks,
Hein

    Comment by Charles Benson on 09 Feb 2010 at 19:58:32  | |responses: 1|
    I did a google search on "chemical resistance guide", then you arrive at varous electronic chemical resistante guides. One of them states the following:

    Glycerine (Concentration 100%) Aliases Glycerine, Glycerol, Glycol Alcohol,
    Propanetriol (1,2,3-)

    Resin - Max Temperature °C

    Unsaturated Polyester (Dicyclopentadiene, DCPD based): 30 - 70
    Vinyl Ester - Bisphenol A: 90 - 100
    Vinyl Ester - Urethane - Bisphenol A: 90 - 100

    The list contains several Polyester and Vinyl Ester/ Epoxy based resins. Taking the solving power of Glycerol into account, the list might be too optimistic. Maybe you can ask Composite Agency to simulate the Glycerol exposure for you - addition of glass fibres is incorporated in their high-tech program. It is either way interesting to see how the results from their Chemical driven FEM Simulation program compare to this list and other Chemical Resistance Guides for Epoxy, Polyester and Vinyl Esters resins in general.

    Charles


      Comment by Composite Agency on 11 Feb 2010 at 22:12:31  | |responses: 0|
      These sorts of chemical resistance (glycerol in thermoset resins) inquiries look simple, but they are rather complex due to their reliance on solubility thermodynamics, diffusion processes and fracture mechanics.

      The above list gives a rough indication of the applicability. The volume uptake of Glycerol should not exceed the 4.5 vol% to 6.5 vol% depending on the resin and specific glass reinforcement considered. At that volume uptake the material and the glass fibre - matrix restraint becomes critical and fracture will occur. The background of this list could be the same.

      For practical reasons, chemical resistance guides have the set-up and appearance as shown above. From our viewpoint these chemical resistance selectors can surely be of indicative support to inexperienced users, but it lacks critical information chemical-physical parametric information on what actually happens.

      Therefore, the effect of temperature and pressure variations, the influence of type of reinforcements (glass veil, chopped strand mat, woven roving, glass fibre, carbon fibre, aramide fiber), the influence of shape (thick wall of thin walled cylinder) are hard to assess. We opt for a more fundamental approach to chemical resistance, including surface corrosion, solubility, swelling, plasticizing, diffusion effects and forthcoming mechanical retention analysis. This all has been implemented in our CheFEM (Chemical driven FEM Simulation) program. Which can analyse cured as well as uncured resins.

      Note that CheFEM chemical resistance routines can handle the following thermoset polymers: Polyesters, Vinyl Esters, Epoxy Esters, Furans, Phenolics, Phenol-Formaldehyde, Siliconces, Polyurethanes, Melamines, Alkyds, Ureas, Allyls, Polybutadienes, Polyimides and Cyanate Esters. The corrosion selector simulation / guide handles the following thermoplastic polymers:
      Polyvinylidine Fluoride (PVDF), Polyetherether Ketone (PEEK), Polyamide (PA), ETFE (Ethylenetetrafluorethylene), Polyphenylene Oxide (PPO), Polyphenylene Sulfide (PPS) and many others.
      Some chemicals for corrosion evaluation are Glycerol, Carbonic Acid, Sulphuric Acid, Nitric Acid, Chlorine and Bromine gas, Hydrofluoric Acid, Water, Distilled Water, Salt Water, Diesel Fuel, Jet Fuel, Indolene, Aviation Oil, Gasoline, Toluene, Benzene, Xylene, Bisphenol, Methanol, etc.

      Interesting case story:In glass fibre reinforced plastics (GFRP) or glass fibre metal laminates (FML's) the combination of the different components do substantially increase the mechanical properties of the material, think for example of high toughness, very long critical crack lengths, etc. At the same time the behaviour of these materials when exposed to chemicals, high pressure and high temperature is becoming more and more complex. For fully integrated chemical-physical service life time predictions, the situation at the interface should often be the focal point of analysis and simulation. Here, possible voids do appears, temperature or swelling stress beyond the interfacial strength may come into play, cohesive strength, adhesive work, interlaminar shear strength values, pull and peel tests, etc. The attached paper is one of our first works on this subject and was published in the framework of ESAT 2006: Osmosis in Composite Materials