CTPB = carboxyl-terminated polybutadiene

Crawford bomb 66 cresylite = mixture of trinitrocresol and picric acid (french) crimping 66 critical diameter 66 CR-propellants = RDX containing rifle powders (USA) cross section ratio -> propellant area ratio 269 crusher 149 362 C.TD. = coefficient of detonation transmission (coefficient de self exitation) (french) 87 CTPB = carboxyl-terminated polybutadiene (USA) 61 329 cumulative priming 66 c.u.p. = coefficient d utilisation pratique (french) 198 cuprene 52 cupric salicylate 163 curing 67... 

A Comparison of a Carboxyl-Terminated Polybutadiene-Based Propellant (CTPB) Using N-Butylferrocene as Burning Rate Catalyst With a CTPB—Based Propellant Using Biradical Burning Rate Catalyst... 

This paper discusses the three butadiene prepolymers which have been used most extensively in solid rocket propellants—i.e., the copolymer of butadiene and acrylic acid (PBAA), the terpolymer of butadiene, acrylic acid, and acrylonitrile (PBAN), and the carboxyl-terminated polybutadiene (CTPB). Since the chemistry of all of these carboxyl-containing prepolymers is essentially the same, the discussion of butadiene propellants in this paper is concerned mainly with those based on CTPB. 

Curing Agents for Carboxyl-Terminated Polybutadiene Prepolymers. The types of curing agents used to prepare binders for CTPB propellants are the same as those for PBAN or PBAA. The bifunctionality of CTPB, however, requires that part of the curing agents be polyfunctional to provide for the formation of the tridimensional network. Almost without exception, the polyfunctional aziridines and epoxides used with CTPB undergo side reactions in the presence of ammonium perchlorate, which affects the binder network formation. Kinetic studies conducted with model compounds have established the nature and extent of the cure interference by these side reactions. The types and properties of some of the crosslinkers and chain extenders used to prepare solid propellants are summarized in Table IV. 

Effects of Curing Agent Type. Epoxide-Cured Propellant. Carboxyl-terminated polybutadiene is a linear, difunctional molecule that requires the use of a polyfunctional crosslinker to achieve a gel. The crosslinkers used in most epoxide-cured propellants are summarized in Table IV and consist of Epon X-801, ERLA-0510, or Epotuf. DER-332, a high-purity diepoxide that exhibits a minimum of side reactions in the presence of the ammonium perchlorate oxidizer, can be used to provide chain extension for further modification of the mechanical properties. A typical study to adjust and optimize the crosslinker level and compensate for side reactions and achieve the best balance of uniaxial tensile properties for a CTPB propellant is shown in Table V. These results are characteristic of epoxide-cured propellants at this solids level and show the effects of curing agent type and plasticizer level on the mechanical properties of propellants. 

Problem 4.4 A sample (3.0 g) of carboxyl terminated polybutadiene (CTPB) required titration with 20 mL 0.1 N KOH to reach a phenolphthalein end point. Calculate M of the polymer. 

Reaction with acid then yields carboxyl-terminated polybutadiene (CTPB). Hydroxyl end groups are provided by termination with ethylene oxide ... 

For end-group analysis, 0.8632 g of a carboxyl terminated polybutadiene (CTPB) sample dissolved in 1 3 mixture of ethanol and toluene consumed 5.2 ml of 0.1240 N alcoholic potassium hydroxide solution in titration using phenolphthalein as the indicator. Calculate the molar mass of the polymer. [Ans. 2672 g mol ]... 

Table 7 Values of Constants K and a from the Relation [nl = KM for Carboxyl-Terminated Polybutadienes (CTPBs)...

The high-polymeric binders in use today include polysulfides (PS), polybutadieneacrylic acid (PBAA), polybutadiene-acrylonitrile (PBAN), polyurethane (PU) and carboxyl- and hydroxyl-terminated polybutadiene (CTPB and HTPB). 

Several types of carboxyl and hydroxyl terminated polybutadienes are made in Japan. The Nippon Soda Co. offers liquid polybutadiene of various molecular weights [273]. These materials have high vinyl content (90%) and are of high viscosity. The carboxy-terminated polybutadienes (CTPBs) of molecular weights 3000 and 4000 are the main products commercially available from Japan at this time. 

Writing the polymerisation reactions for the formation of Polyesters from (o-hydroxy acids and formation of carboxy terminated polybutadiene (CTPB) from butadiene in presence of an azo initiator, predict the number of carboxyl groups per molecular chain in each case. 

---