Liquid polybutadienes

Some technological information on the Aerojet General Corporation s composite propellants technology was published recently [20]. Ammonium perchlorate is ground to the particle sizes ranging from 1 to 200 fx and then mixed to form a blend of the various particle sizes which gives the best mechanical and ballistic properties. Ammonium perchlorate is mixed with liquid polybutadiene-acrylonitrile fuel, liquid plasticizer and aluminium powder (Fig. 118). The motor casing is coated internally... 

C EN 42, 50-3 (Sept 28, 1964) [Description of cast composite proplnts manufd at Aerojet -General Plant, near Homestead, Florida, for use in large rocket motors, such as 120 156l, diam. Ammonium perchlorate, (previously ground to particles ranging from 1 to 2 microns and blended with ca 0.2% of tricalcium phosphate to improve their flow props), is used as an oxidizer. Aluminum powder is used as a fuel and liquid polybutadiene-acrylonitrite as the fuel-binder. To these ingredients are added a catalyst, such as iron oxide (to... 

DMTA is a very interesting tool for characterizing heterogeneous materials in which domains of distinct Tg values coexist. The most interesting cases involve modified thermosets of different types (see Chapter 8). Examples are the use of rubbers (e.g., liquid polybutadiene and random copolymers), or thermoplastics (e.g., polyethersulphone or polyetherimide in epoxy matrices or poly(vinyl acetate) in unsaturated polyesters), as impact modifier (epoxies), or low-profile additives (polyesters). The modifier-rich phase may be characterized by the presence of a new a peak (Fig. 11.10). But on occasions there may be superposition of peaks and the presence of the modifier cannot be easily detected by these techniques. If part of the added polymer is soluble in the thermoset matrix, its eventual plasticizing effect can be determined from the corresponding matrix Tg depletion, and the... 

It should be noted that, unlike Ag nanocrystals of Ag-PPX nanocomposites with 2max of plasmon band in the range 430-445 nm, nanocrystals prepared by reduction of Ag+ ions in solution of poly (N-vinylpyrrolidone) [81] as well as nanocrystals formed by introducing Ag vapors into liquid polybutadiene [77] have plasmon band with 2max around 410 nm. As is specified in Ref. [81], the UV-vis spectrum of nanocrystals depends on their size and form as well as on the surrounding matrix. The plasmon band of Ag nanocrystals [77, 81] coincides with that of modeling spherical nanoparticles with a smooth ideal surface, which were theoretically treated from different points of view in Ref. [82, 83]. 

Solvent resistant laminates for printed circuits were manufactured by coating of copper foil with a solution of PPO, BPA/DC, bis(4-maleimidophenyl) ether and Zn octoate in toluene the coated foil was laminated with PPO-impregnated glass fabric [47]. Similar result was achieved by the modification of PPO with polyfunctional cyanates or maleimides, liquid polybutadiene and a polymerization catalyst [48], A solvent and heat resistant composition for printed circuits consists of copoly [(2,6-dimethylphenylene)-(2,3,6-trimethylphenylene)]oxide, maleic anhydride grafted poly-1,2-butadiene, bis(4-maleimidophenyl)methane, BPA/DC and toluene. BPA/DC prepolymer may be used instead of the monomer [49]. 

Functionalized, liquid polybutadiene derivatives have also been developed as hybrid flexiblizers for epoxy resins. Carboxyl-terminated butadiene/acrylonitrile polymers, butadiene homopolymers, and maleic anhydride-amino acid grafted butadiene homopolymers have been used as flexibilizers to impart good low-temperature strength and water resistance to DGEBA-based epoxy adhesives. An epoxy system toughened by polybutadiene with maleic anhydride is claimed to provide a hydrophobic backbone, low viscosity, softness, and high tensile strength and adhesion (Table 7.10). 

Synthetic polymers from alkene monomers are also a major target for epoxidizers. Polyisoprenes,26 polybutenes and polybutadienes have all been epoxidized by general in situ peracid methods. In the case of liquid polybutadienes, a wide range of types is available. Products with varying contents of 1,4-cis, 1,4-trans, and 1,2-vinyl alkene groups are available (Figure 3.6). 

Table 4.6. Effect of fillers on the properties of crosslinked liquid polybutadiene containing hydroxyl end groups 253)...

Barcia, F.L. Amaral, T.P. Soares, B.G. Synthesis and properties of epoxy resin modified by epoxy-terminated liquid polybutadiene. Polymer 2003, 44, 5811. 

Talon, O. Couvercelle, J.P. Bunel, C. Impact modification of polyamide-12 through blending with liquid polybutadiene. E-Polymers 2003, 1, 1-19. 

Liquid polybutadienes without functional groups may be vulcanized on double bonds of the diene part of the polymeric chain in the presence of a sulfur-accelerating, redox, or peroxide system. However, only the sulfur-accelerating system is able to provide the maximal durability values. Sulfur also has other advantages such as low price, availability, and so on. The amount of involved sulfur in the system depends on the desired properties of the product. For hard RubCon, this is 47-55 mass parts per 100 mass parts of rubber. 

METHOD OF THERMAL TREATMENT OF A PROTECTIVE COVERING BASED ON LIQUID POLYBUTADIENE BINDER BY ELECTRIC CURING [31]... 

The much greater stability of the growing polydienyllithium chain end compared with the growing polyethylenyllithium chain end has been demonstrated in a recent patent to McElroy and Merkley (9). Table IV shows that the yields of liquid polybutadienes produced per equivalent of catalyst at 100 °C are about the same as those produced at 40° or 60 °C although the rates of chain transfer to toluene solvent are significantly affected. 

Luxton, A.R., 1981. The preparation, modification and appUcations of nonfunctional liquid polybutadienes. Rubber Chem. Technol. 54 (3), 596-626. 

Hydroxy-terminated liquid polybutadienes are prepared for reactions with diisocyanates to form elastomeric polyurethanes (see Chapter 6). Such materials can be prepared by anionic polymerizations as living polymers and then quenched at the appropriate molecular weight. These polybutadienes can also be formed by a free-radical mechanism. The microstructures of the two products differ, however, and this may affect the properties of the finished products. To form hydroxy terminated polymers by a free-radical mechanism, the polymerization reactions may be initiated by hydroxy radicals from hydrogen peroxide. 

Discuss liquid polybutadienes. How are they prepared and used ... 

These addition reactions of unsaturated polymers, like liquid polybutadiene, developed into preparations of useful commercial materials. The patent literature describes procedures that use hydrogen peroxide in the presence of organic acids or their heavy metal salts. Reaction conditions place a limitation on the molecular weights of the polymers, because it is easier to handle lower-viscosity solutions. A modification of the procedures is to use peracetic acid in place of hydrogen peroxide. The most efficient methods rely upon formations of organic peracids in situ with cationic exchange resins acting as catalysts. This can be illustrated as follows ... 

The control of chain structure and molecular weight afforded by the organolithium polymerization of dienes, has, of course, been of great technological interest [161,162,209]. Such product developments have been mainly in the form of (1) polybutadiene elastomers of various chain structures [162, 198,209] and functional end groups [210], (2) liquid polybutadienes [211], (3) butadiene-styrene copolymers (solution SBR) [69, 161, 162, 209], and (4) styrene-diene triblock copolymers (thermoplastic elastomers) [212]. 

Polyurethane (PU) PV membranes were reported by Schauer et al. (1999). PU membranes were prepared by the reaction of toluene-2,4-diisocyanate with hydroxyl-terminated oligomers. Oligomers were either liquid polybutadiene (PB) (MW 3000) or propylene oxide-based PEs (MW 420 and 4800). The prepared membranes were used in PV of binary mixtures of water-EtOH, water-dioxane, and EtOH-toluene, respectively. Membranes obtained from the polymer quatemized poly[3-(N, N -dimethyl)aminopropylamide-co-acrylonitriles] showed selective separation of water from aqueous EtOH solution by PV (Yoshikawa et al. 1991). The separation factor toward water reached over 15,000. Membrane performance showed a good correlation to membrane polarity. DSC melting endotherms of the water-swoUen membranes were studied to clarify the state of water in the membrane. The resnlts suggested that there were two states of water in the membrane bound and free. The higher the fraction of bound water in the membrane, clearly, the more preferentially was water permeated. 

In some applications of interest to us, notably solid fuel rocket propellants, polybutadiene is used as the soft segment of a polyurethane rather than as bulk polymer. Hence, our studies of the role of amines in adhesion have been extended to include systems with polyurethanes derived from functionalized liquid polybutadiene. 

The use of elastomeric or flexibilizing modifiers occurred and grew with epoxy resins first. Various aspects of toughened epoxy adhesives have been covered in reviews by the present authors (2,3), where the elastomeric modifiers have essentially been carboxylic, liquid and solid butadiene/acrylonitrile polymers. There has not been a systematic review, however, of these and other reactive liquid polybutadiene/acrylonitriles in the burgeoning areas of acrylic, anaerobic and radiation-curable systems. Thus, this paper s intent. 

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