TiO2 Opacifier Static Test: First Look



At Richard Nakka's site on sorbitol propellant (KNSB) it says:
The cast KNSB grain is somewhat translucent with the colour being nearly pure white. As a result of the translucent nature, it may be prudent to add an opacifier, such as lampblack, to absorb the heat of reaction and reduce infrared transmission of heat through the grain (which may result in accelerated burning rate). This is an aspect of the propellant that requires further investigation.

And so the questions start:

Single grains for static testing:
0%, 1%, 2%, and UltraPink 1%+1%RIO:


Note the translucent nature of the KNSB with no opacifier added.





Results Calculated:
 
Code
Total Imp NS
Avg thrust N
Burn time
Peak thrust
%ISP of control
TiO2-0%
D-8
10.98
7.84
1.4
14.24
100%
TiO2-1%
D-5
10.73
5.47
1.96
10.68
96%
TiO2-2%
C-5
9.62
5.09
1.89
8.9
86%


The apparent 4% "loss" of ISP in the 1%TiO2 is within the statistical variation (~10%) of these motors so may mean nothing. Would have to do a bunch of tests to see if this is a true loss. Doesn't seem worth all that effort to check.

More interesting question relates to recent SugPro discussions. If dark opacifiers, like lampblack, increase the burn rate and this white opacifier slows down burn rate then in theory one could "dial in" their burn rate by controlling the ratio of both opacifiers in a formula. Anything from fast to normal to slow burn rates with opacification as a bonus.
In my lower pressure motors I do not see a burn rate increase with carbon opacifiers so my system won't be able to try this dial in approach with lampblack and TiO2.
Perhaps I could try one of the iron oxides and TiO2 as a way to be able to dial in burn rates ?
Wow, so many questions, so little rocket time.











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