Study On Preparation Of Polymer Flame Inhibitor For Gunpowder

Propellant gun firing will produce secondary flame, usually small molecules potassium flame inhibitor be used to prevent the secondary flame. Traditional used of small molecules potassium flame inhibitor was crystals when set into the powder and easily absorb moisture, and molecular migration occurs during storage. As the shortcomings of the traditional used potassium salt become increasingly evident, therefore, to synthesize the polymer flame inhibitor which can disperse in the powder, the absorption rate is low, and anti-migration when in the gunpowder is significant.K+ plays a primary role in elimination of secondary flame, along with other groups containing N. Therefore, the polymer must contain as much flame extinction elements as possible during the synthesis of polymers. In this study two types of polymer flame inhibitor were synthesized, i.e. K-type flame inhibitor: polyacrylate potassium, poly(N-acryloyl-glycinate potassium); nitrogen-rich-type flame inhibitor: poly(N-acryloyl-aminotetrazole). Poly (N-acrylic acid - glycine potassium) and poly (N-acryloyl - Aminotetrazole) are two new polymers containing the suppressor element which were not reported in national, and poly (N-acrylic acid - glycine potassium ) in a high potassium consumption, while also containing flame inhibitor group N.Polyacrylate potassium was synthesized by introducing element K into olefine acid monomers and then generating polymerization through radical. Orthogonal experimental method was used to obtain the better synthetic conditions of the polymer which is moderate molecular weight, high K content and low moisture absorption rate, and performance comparison with polymethyl methacrylate potassium was made. Glycine was used as reactant during synthesis of poly(N-acryloyl-glycinate potassium). Acryloyl chloride reacted with glycine in concentrated KOH solution, lead to the production of N-acryloyl-glycinate potassium. Then potassium persulfate was used to initiate its polymerization. the polymer have the highest potassium content and the lowest moisture absorption rate when the ratio of acryloyl chloride to glycine was 1:1.2. Acryloyl chloride was also used in the polymerization of poly(N-acryloyl-aminotetrazole). Chlorine atoms reacted with amino group on 5-amino-tetrazole. Then potassium persulfate was used to initiate its polymerization. The introduction of amino tetrazole ring has granted poly(N-acryloyl-aminotetrazole) the performance of being soluble in organic solvents.Infrared spectroscopy was used to characterize polymer structure. The element K content of polyacrylate potassium and poly(N-acryloyl-glycinate potassium) was measured by indirect titration using sodium tetraphenylborate and benzalkonium bromid. Ubbelohde viscometer was used to determine the intrinsic viscosity of the polymer. Through the intrinsic viscosity to compare the molecular of the polymer, study the effect of the polymerization condition to the the molecular of polymer. The moisture absorption of the polymer placing a certain time was measured using standard humidity field of saturated sodium chloride and potassium acetate solution. Also determined the solubility of the poly(N-acryloyl-aminotetrazole)in selected solvents.The content of element K in Potassium polypropylene, poly(N-acryloyl-glycinate potassium) is comparatively high that almost reach to the theoretical value. poly(N-acryloyl-aminotetrazole) introduced amino tetrazole ring which is of high nitrogen content and easy to break down when decompositing will produce a large number of non-flammable gas N₂, all the three mentioned above qualified the basic performance required for flame inhibitor.