multicomponent solvent interactions in CheFEM?

Thread by Marc Connor on 30 Nov 2009 at 14:16:17 
Can multicomponent solvent interactions (think of carbon dioxide, hydrogen sulfide, water, hydrogen cyanide and nitrogen dioxide) be evaluated using CheFEM simulation? I am interested in solubility and swelling phenomena, diffusion and (simultaneous or subsequent) corrosion? Thanks, Marc

    Comment by Composite Agency on 13 Dec 2009 at 14:20:28  | |responses: 3|
    Thanks for this post (we will definitely place this one in FAQ's for the software!).

    Multicomponent solubility and diffusion can be evaluated with CheFEM. The species data that is required for the lattice based thermodynamical and diffusion routines, are free volume, chemical interaction parameters (Hildebrand* solubility parameters) and density. For all species and polymers this data is available within existing literature and within the CheFEM simulation device.

    Regarding chemical reactions: these have partly been programmed but can also be backed-up with existing library information. For example, with the library for corrosion reaction of metals is based on the second edition of the Handbook of Corrosion Data from ASM Internationals (edited by Bruce D. Craig and David B. Anderson). For reaction rates of e.g. fibre sizings more specific routines are used.

    Hope this helps at this point. Please do not hesitate to contact us for more information (case studies etc.)

    Composite Agency

    * Please check the tables in the support section for a small overview.

      Comment by Marc Connor on 05 Jan 2010 at 18:32:39  | |responses: 2|

      I have two additional questions on the Chemical driven FEM Simulation program:

      - What does Mechanical / Swelling Restraint mean?
      - What is the effect of physical ageing on predicted behaviour: for example how is diffusion and swelling influenced by ageing?


        Comment by Composite Agency on 07 Jan 2010 at 22:02:07  | |responses: 1|
        Swelling restraint is the restraint of mass and temperature driven due to adhesional / cohesional restraint by crystalline areas, chains of high molecular weight, and filler particles, like fibres. For aged materials, the swelling restraint usually decreases because the material relaxes, the adhesive degrades slowly etc. Hence, expansion increases over time. At the same time, the free volume of the polymer decreases as a result of physical ageing, this will result in lower diffusivities. For swollen polymers, the net effect will be an increase in permeation rate over time.

        Kind Regards,
        Composite Agency

          Comment by Marc on 15 Jan 2010 at 12:18:17  | |responses: 0|
          Thanks. So the depicted swelling isotherms for CO2 in Epoxy (picture in news section) changes over time? For proper design of oil and gas equipment (also think of applications containing PVDF) I can imagine that the swelling / expansion isotherms over time are of major importance. If the coating or structural material swelling beyond the specifications, the proof of the lifetime pudding is in the eating!