hindsight Posted October 7, 2013 Posted October 7, 2013 Mumbles, the compatibility issue was the concern and the rapid answer is appreciated.
Jonathan Posted October 10, 2013 Posted October 10, 2013 A great mix: 1.1g Sb2S3 + 1g KClO4 + 0.1g phenolic resin. Big, beautiful, smoky, flash.
WonderBoy Posted October 11, 2013 Posted October 11, 2013 Over on Fireworking there has been a lot of discussion about using a phenolic resin and hexamine mix to make large comets that can be "cured" overnight and shot the next day. Some 8" comets were made and shot at the PGI convention using this method. Since then, several people have been making and shooting more normal sized comets(~3"). WB
hindsight Posted October 12, 2013 Posted October 12, 2013 (edited) Thanks WB, your comment finally induced me to subscribe to Ned's site, a worthwhile investment. An interesting point he made was that the hexamine cross-linked the phenolic resin during the overnight heat treatment. The resin I have is presumably already a polymer. In the recipe, you add the metal du jour. Always looking for a short-cut, I wonder how it might work without ball-milling and without "baking". Edited October 12, 2013 by hindsight
Jonathan Posted October 12, 2013 Posted October 12, 2013 Great. Now my question remains whether 200 proof ethanol can be used with the oxidizer KClO4 (not referring to solubility). Jonathan, just out of curiosity, you know it's hexamine-cured because of what? Smell? Has your supplier (thought we had same source) identified the type of phenolic resin? Thanks. Smell. The way it behaves -- predictably according to stoichiometric calcs. The way it looks. The fact it's completely insoluble in water. The seller's representations. The ways others have described Novolac-type phenolic resin. All consistent circumstantial evidence.
hindsight Posted October 12, 2013 Posted October 12, 2013 (edited) .... All consistent circumstantial evidence.Well, then, I am convicted (that it's Novolac, that is). Although my supplier (same as yours?), contacted me yesterday to say he was still trying to find out exactly what it is he sent me. There is little detectable smell , it is essentially insoluble in 70% isopropyl alcohol (awaiting arrival of absolute ethanol) and looks like the picture oldguy posted early in this thread. Edited October 12, 2013 by hindsight
Mumbles Posted October 12, 2013 Posted October 12, 2013 My phenolic is insoluble in 70% as well, which isn't surprising. 91% isopropanol works okay, as does denatured alcohol. I got mine from Jim Widmann. I'm not sure what sort of type it is, but it definitely has an odor of free phenol.
FlaMtnBkr Posted October 13, 2013 Posted October 13, 2013 Hindsight - completely off subject, but do you build airboats? Just curious.
hindsight Posted October 13, 2013 Posted October 13, 2013 (edited) FlaMtnBkr -- Epoxy-based non-motored watercraft. Just a hobby -- making fishing platforms. Nothing for the Everglades, nor racing, sorry. Back on topic:..... An interesting point he made was that the hexamine cross-linked the phenolic resin during the overnight heat treatment. .. Since Ned probably uses Jim's phenolic resin, as well, and the resin may have some unreacted phenol per Mumble's sniff test, the idea of additional curing with heat and hexamine is not too far afield(?). Edited October 13, 2013 by hindsight
FlaMtnBkr Posted October 13, 2013 Posted October 13, 2013 Just curious since you're into boats and planes and making things. Hey that rhymed
pyrojig Posted October 13, 2013 Posted October 13, 2013 Thanks WB, your comment finally induced me to subscribe to Ned's site, a worthwhile investment. An interesting point he made was that the hexamine cross-linked the phenolic resin during the overnight heat treatment. The resin I have is presumably already a polymer. In the recipe, you add the metal du jour. Always looking for a short-cut, I wonder how it might work without ball-milling and without "baking".This is a interesting idea, and one that would prove very handy in the field ( or event ). I have heard of using hexamine as a curing agent, but am more interested in its use with phenolic resin. I have obtained a fair amount of phenolic resin and some hexamine. Is there a specific method to activating the resin via a crosslinking solvent ?
Jonathan Posted October 17, 2013 Posted October 17, 2013 Mixed 0.25g Hexamine + 1g NaClO4. Produced big, bright fireball
pyrojig Posted October 18, 2013 Posted October 18, 2013 @ Jonathan Please keep the topic on track. It is a discussion of Phenolic resin and its uses as a binder and a fuel . Now back to topic : Is there any reason to need to crosslink phenolic resin to speed dry it , or is there much diff in the dry time of just using a solvent ( 100% alc, etc)?
hindsight Posted October 23, 2013 Posted October 23, 2013 pyrojig-- Haven't ignored your question, just been waiting for a polymer chemist in the audience to come forward and de-mystify matters. My experience is only with the practical use of epoxy resin, which contain, I think, phenolic dimers and are crosslinked by the addition of amine hardeners (curing agents). Some epoxies cure at room temp and others require an elevated temperature (boat builders call it "post curing"). But epoxies aren't synonymous with phenolic resins+hexamine.And someone will have to explain if dissolving Novalac phenolic resin in ethanol to use as a binder results in a hard star/comet/propellant just because the solvent evaporated or if the hexamine is actually crosslinking the already-polymerized Novalac (say, in a 3D manner) to further harden the binder with the addition of heat. I now have the phenolic resin (presumed Novalac) and the ethanol but am awaiting the arrival of an appropriate style blender to pulverize the resin. So when the opportunity arises, an unscientific comparison will be made with and without hexamine to test the hardness of phenolic resin evaporated from alcohol. If someone has done this and can save me the aggravation that would be great.
Nessalco Posted October 23, 2013 Posted October 23, 2013 The posts on Fireworking specify using 8% (87% phenolic + 13% hexamine) in denatured alcohol, cured overnight at 120F. That's using Jim Widmann's resin. Kevin
hindsight Posted October 24, 2013 Posted October 24, 2013 Nessalco, Assume you mean 8% of the total comp is binder. So if the phenolic is 87% of that 8%, then you're saying that the phenolic makes up approximately 7% of the total comp and hexamine comprises approximately 1% of the total comp. (Or are you saying that it's an 8% phenolic in alcohol solution?) Still the question posted above remains about the role of the hexamine. (Yes, of course, it's fuel, as I've had many a meal cooked over Esbit's Brennstoff).
hindsight Posted October 25, 2013 Posted October 25, 2013 Finely pulverized some phenolic resin in a blender and attempted to dissolve 8grams in 100ml absolute ethanol (actually 95% ethanol with methanol & isopropanol as denaturants) at 25C. Success was finally achieved but required prolonged stirring. For some reason I expected greater solubility.Jonathan, when you combined the presumed identical resin with absolute ethanol, you said it dissolved "like a champ". Can you roughly quantitate the solubility?
pyrojig Posted October 26, 2013 Posted October 26, 2013 My phenolic resin dissolves in 100% lab grade isopropanol with some stirring . Ethanol may be a better alcohol to dissolve in , as it is with other things. I would say about a few min to get the resin to go into sol. with stirring .
hindsight Posted October 26, 2013 Posted October 26, 2013 Pyrojig-- Are you able to achieve at least an 8% weight/volume solution of phenolic/isopropanol? To say something is soluble, technically, means you can get 1gram to dissolve into 100ml of solution. In order to have a reasonable test as to whether further curing of phenolic resin occurs with the addition of hexamine, it would be useful to have a fair mass of the stuff in solution. When I dissolved the 8 grams of phenolic resin in slightly warm absolute ethanol it was pretty well saturated, as evidenced by the solution becoming turbid as the temperature dropped a bit below room temp (unless the precipitate was a new compound with lower solubility). Looks like a lot of ethanol will have to be evaporated in order to test the phenolic with and without hexamine for curing. And it's not clear whether this represents the reality of 1) hexamine+phenolic+other comp ingredients wet with ethanol or 2) hexamine+ other comp ingredients wet with phenolic/ethanol. Really doesn't matter, I guess, as long as a recipe for stars with hexamine and phenolic produces a hard enough star that has a good effect. It's just that little itch...
Nessalco Posted October 26, 2013 Posted October 26, 2013 Nessalco, Assume you mean 8% of the total comp is binder. So if the phenolic is 87% of that 8%, then you're saying that the phenolic makes up approximately 7% of the total comp and hexamine comprises approximately 1% of the total comp. (Or are you saying that it's an 8% phenolic in alcohol solution?) Still the question posted above remains about the role of the hexamine. (Yes, of course, it's fuel, as I've had many a meal cooked over Esbit's Brennstoff).Hindsight, 8% of the total comp is a mix of 87% phenolic and 13% hexamine. These elements are added to the screened, dry mix. 10% denatured alcohol (by weight) is added to the dry mix to activate the resin. As I understand it, the role of the hexamine + elevated temperature is to support crosslinking of the phenolic resin. I'm no chemist, but the idea of curing display comets in 12 hours is very appealing. Kevin
hindsight Posted October 27, 2013 Posted October 27, 2013 Nessalco, Thanks for the clarification and additional details of the process. (And my chemistry background is prehistoric ; a few cave drawings of Grignard reactions were sketched by my hand). The question, as stated before, regards the role of crosslinking with hexamine and whether it adds to the hardness. Yes, it would be wonderful to have fast-food turn-around for making comets. Would you like to super-size that?
pyrojig Posted October 27, 2013 Posted October 27, 2013 I have been using 6% resin in 100g of alcohol as a binder for several color stars. They do harden very well. It seems that one could dry mix as stated and get a good result. I have never tried this method. I like using a laq. spray to bind my stars when rolling .
hindsight Posted October 27, 2013 Posted October 27, 2013 I have been using 6% resin in 100g of alcohol as a binder for several color stars. They do harden very well. It seems that one could dry mix as stated and get a good result. I have never tried this method. I like using a laq. spray to bind my stars when rolling . Pyrojig,Since the density of isopropanol and ethanol are both around .79 mg/ml, 100grams of alcohol is approximately 127 ml. At 6% (weight/volume I assume) phenolic resin, that's close to 7.5 grams of phenolic resin. What's the weight of your comp before spraying the solution on it?Thanks for your input.
jerronimo Posted November 3, 2013 Posted November 3, 2013 Mia I don't get it, You're saying that u have phenolic resin that is superior to every other binder.But why don't you give us the type that u use?I get it that u don't share formulas but surely you can give us the type and brand of resin that u use.
pyrojig Posted November 12, 2013 Posted November 12, 2013 Pyrojig,Since the density of isopropanol and ethanol are both around .79 mg/ml, 100grams of alcohol is approximately 127 ml. At 6% (weight/volume I assume) phenolic resin, that's close to 7.5 grams of phenolic resin. What's the weight of your comp before spraying the solution on it?Thanks for your input.Well the weight of the comp is not important when rolling round stars .I use the spray out of a atomized sprayer. The quantity is not critical(as far as a weight of binder to comp), being the proper ratio is in solution . Just use as much as needed to get your stars to the proper size.
Recommended Posts