摘要:
ABA triblock and A.sub.n B star polymers are produced by sequential cationic polymerization of 4 and 5 member ring cyclic ethers to initially form a B block and subsequent cationic polymerization of 4 and 5 member ring cyclic ethers to form A blocks at the termini of the B block. The B block is grown from the hydroxyl groups of a polyol having two or more hydroxyl groups, resulting in a B block having terminal hydroxyl functionality of two or greater. In growing each of the B and A blocks, the acid catalyst is used at a molar ratio relative to hydroxyl groups of the polyol initiator of between about 0.05:1 and about 0.5:1.
摘要:
A method of preparing a thermoplastic elastomer having A blocks and at least one B block, wherein said A blocks are crystalline at temperatures below about 60.degree. C. and said B block is amorphous at temperatures above about -20.degree. C., said A blocks each being polyethers derived from monomers of oxetane and its derivatives and/or tetrahydrofuran and its derivatives, the method comprising:providing monofunctional hydroxyl terminated A blocks which are crystalline at temperatures below about 60.degree. C. and separately providing di-, tri- or tetrafunctional hydroxyl terminated B blocks which are amorphous at temperatures above about -20.degree. C.,end-capping said A blocks by separately reacting said A blocks with a difunctional diisocyanate in which one isocyanate moiety is at least about five times as reactive with the terminal hydroxyl group of the A blocks as the other isocyanate moiety, whereby the more reactive isocyanate moiety tends to react with the terminal hydroxyl group of the A blocks, leaving the less reactive isocyanate moiety free and unreacted, andadding di-, tri- or tetrafunctional B block to the end-capped A blocks at approximately the stoichiometric ratios that they are intended to be present in the thermoplastic elastomer such that the free and unreacted isocyanate moiety on the end-capped A block reacts with a functional moiety of the B block to produce ABA or A.sub.n B thermoplastic elastomers.
摘要:
Vinyl ethers for use as bonding agents in solid rocket propellants are disclosed. The vinyl ether bonding agents are capable of polymerizing in the presence of and around the surface of ammonium perchlorate particles. The bonding agents of the present invention are added to the propellant in a range from about 0.1% to about 3% by weight concentration. Importantly, there is no increase in ammonia liberated above baseline propellant values and no increase in end of mix viscosities by using the vinyl ethers according to the present invention which provides substantial processing savings.
摘要:
Cyclic ethers having 4 and 5 member rings are polymerized with a alcohol initiator and an acid catalyst. The acid catalyst is used at a molar ratio relative to hydroxyl groups of the alcohol initiator of between about 0.05:1 and about 0.5:1.
摘要:
Hexabenzylhexaazaisowurtzitane is converted to tetracetyl, dibenzyl azaisowurtzitane. The benzyl groups are removed by catalytic transfer hydrogenolysis leaving a pair of available nitrogens. The available nitrogens are acetylated, and the resulting intermediate is converted to CL-20 with a strong nitrating agent.
摘要:
A thermoplastic, elastomeric block copolymer comprises at least one poly(butadiene) and at least one pair of poly(lactone) blocks flanking the poly(butadiene) block. Each poly(lactone) block is derived from a lactone having between 8 and 18 carbon atoms in the lactone ring, such as &lgr;-laurolactone and 10-hydroxyl decanoic acid lactone. Alternative methods of making these block polymers are also disclosed. In the first procedure diethyl zinc reacts with the hydroxyl end group of a butadiene polymer to form an intermediate zinc alkoxide-tipped polybutadiene which functions as the active initiating species. The laurolactone polymer then grows off the hydroxyl end groups of the butadiene to form the desired ABA block copolymer. In another related procedure for making ABA block polymers, previously prepared difunctional hydroxyl-terminated polybutadiene blocks are linked with monofunctional poly(&lgr;-laurolactone) blocks using a diisocyanate and a catalyst. The poly(&lgr;-laurolactone) is prepared from &lgr;-laurolactone, diethyl zinc and a suitable mono-functional alcohol. Another procedure describes the direct linking of hydroxyl-terminated poly(butadiene) with a poly(&lgr;-laurolactone) with a difunctional isocyanate producing a polymeric material having an (AB)n structure. Also disclosed are chemically uncured high-energy compositions, such as explosives, gasifiers, and especially solid rocket motor propellants, wherein between about 70-91 wt. % of solid particulates, including fuel material and/or oxidizer, and between about 9-30 wt. % of a binder system comprising a thermoplastic, elastomeric block copolymer system as above described and optionally a plasticizer.
摘要:
A process for synthesizing 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo-[5.5.0.0.sup.5,9 0.sup.3,11 ]-dodecane ("TEX") involves combining at least one hexa-substituted piperazine derivative with a medium containing at least one nitronium anion source and at least one acid sufficiently strong to generate nitronium anions from the nitronium anion source. According to this invention, TEX yield is significantly improved by pre-heating the medium to 55.degree. C. to about 70.degree. C. and maintaining the medium from 55.degree. C. to about 70.degree. C. to permit the hexa-substituted piperazine derivative and nitronium anions to react and form the TEX. At least one NO.sub.x scavenger is added to the medium, preferably before the addition of the hexa-substituted piperazine derivative, to increase TEX yield.
摘要:
Polymers are produced from 4 and 5 member cyclic ethers, which polymers have hydroxyl functionalities of 4. The cyclic ethers are polymerized with an acid catalyst and a tetraol initiator having the general formula: ##STR1##
摘要:
Hexabenzylhexaazaisowurtzitane is converted to tetracetyl, dibenzyl azaisowurtzitane. The benzyl groups are removed by catalytic transfer hydrogenolysis leaving a pair of available nitrogens. The available nitrogens are acetylated, and the resulting intermediate is converted to CL-20 with a strong nitrating agent.
摘要:
Automotive airbag gas generant formulation providing an alternative to commercially used formulations containing sodium azide. The composition contains from about 25% to about 75% by weight of 5-nitro-1,2,4-trizal-3-one (usually known as nitrotriazolone). The other principal ingredient of the composition is from about 25% to about 75% by weight of an anhydrous oxidizing salt having a cation selected from metals of Group I-A of the Periodic Table (except sodium), calcium, strontium, or barium, and an anion which is essentially free of carbon, hydrogen, or halogens. From about 0.1% to about 5% of a binder can be added, if necessary. An automotive airbag inflator containing the composition and a method for generating gas comprising the step of igniting the composition stated above are also disclosed.