Sulfur does not act as a "binder" in EstesBP rocket engines. There is no need for an additive binder in Estes BP engines, because they press to approx 1.7 g/cc ..at these pressures the fine particles of black powder ie KNO3/S/C undergo a plastic deformation process...ie they become somewhat plasticized and they flow freely into and with one another.

http://en.wikipedia.org/wiki/Plasticity_%28physics%29

Sulfur does act as a pyrolant in black powder ie as an ignition promoter.




As far as Dextrin being used in Estes engines, I too have seen that MSDS..... I once asked a source if Dextrin was every used in the Estes manufacturing process as a binder or anything else..... and I was told no. It may show up on the that old MSDS because it was used a a burn rate modifier in the delay train...... but it was not used in the actual propellant.

If you look at modern day MSDS from the 80's forward you will see no mention of dextrin. Dextrin is a well know binder used by some who make BP pyrotechnic skyrockets. It will also slow down the burn rate. This is favorable in skyrockets as they are have full top to bottom cores and a slower BP is required.



It is my understanding the the large FGH Rocketflite BP engines actually used a water based elastomer as a binder but this was required because of their sheer size and their large cores.... the binder made the pressed BP grains somewhat rubbery so they wouldn't crack and they would adhere better to the casings.

HTH

Terry Dean

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"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them.