Hello.
I=B4m not very skilled in polymer chemistry and need some help.
Me and our research group are trying to disslove HTPB - hydroxyl- terminated polybutadiene (cured with toluene-2,4-diisocyanate). We employed several organic solvents (xylene, benzene, toluene, tetrahydrofuran with AlCl3), but any of these doesn't work.
Does anybody have some idea?
Jan Kupka
kuxpik wrote in news:b8c9fc76-075a-43df-8b41- snipped-for-privacy@p43g2000hsc.googlegroups.com:
Try mixing with heptane, applying shear and some heat. (Choosing a linear non-polar, as opposed to an aromatic or heterocyclic may more closely approximate your polymer backbone, "like dissolves like" right? ;-) Depending upon your crosslink density, swelling your polymer to a gel- like state may be the best you can hope for.
Regards R. David Zopf Bomar Specialties Co.
This will require high pressure bomb with solvent to break down the long chain x links in the rubber. High pressure bombs and small samples of 1 gram or less can be done with various aromatic solvents and chlorinated solvents.
To dissolve polymers - you can use the Hansen solubility theory : Charles Hansen as a way of predicting if one material will dissolve in another and form a solution . They are based on the idea that like dissolves like where one molecule is defined as being 'like' another if it bonds to itself in a similar way.
On the you can find tables with the values of different solvents
kind regards
ir Sven De Vis
Crosslinked polymers are not soluble. The best you can hope for is absorbence of solvent to form a gel. If polymer is just highly branched then others suggestions will work.
hi jan i agree with the last opinion you cant dissolve a cured polymer the only why to do that is find a why to brake the cross-linking bonds only and then you can dissolve the polymer the cross linking bonds are urethane bonds the bast why to try to brake them is by Hydrolysis you can red this page to new more
You all were right. Cured HTPB is not soluble. We hoped at least for a gel, but after a week solution (we tried several solvents and also solvents mixtures) we stopped it, because nothing happened. We will probably have to find out, how to break cross-links between HTPB. If somebody has experience with breaking links, I will appreciate any suggestions.
Hydrolyze links with acid.
Once the polymer is swollen to a gel, a small amount of milling in a high shear mixer is required to produce a pourable viscosity, although because of the crosslinks, it will be much more viscous than an uncrosslinked polymer. One of the best solvents for rubbers is toluene, and this can be blended with other cheaper hydrocarbons like SBPs (special boiling point solvents). Try around 0.1% of morpholine, which can solvate the crosslinks without breaking them, since they will not re-form once broken and an uncrosslinked polymer will have different properties. If you are coating something, the coated surfaces may block (stick together).
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.