Polybutadiene/acrylonitrile

Silicone rubber filled with microspheres and reinforced with a plastic honeycomb Polybutadiene-acrylonitrile elastomer modified phenolic resin with a subliming powder... 

Elastomeric Polybutadiene-acrylonitrile Solid propellant binder... 

Composite proplnts, which are used almost entirely in rocket propulsion, normally contain a solid phase oxidizer combined with a polymeric fuel binder with a -CH2—CH2— structure. Practically speaking AP is the only oxidizer which has achieved high volume production, although ammonium nitrate (AN) has limited special uses such as in gas generators. Other oxidizers which have been studied more or less as curiosities include hydrazinium nitrate, nitronium perchlorate, lithium perchlorate, lithium nitrate, potassium perchlorate and others. Among binders, the most used are polyurethanes, polybutadiene/acrylonitrile/acrylic acid terpolymers and hydroxy-terminated 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... 

PBAN = polybutadiene acrylonitrile PB-RDX = polystyrene bonded RDX, consisting of 90% RDX, 8.5% polystyrene and 1.5% dioctyl-phthalate... 

The high-polymeric binders in use today include polysulfides (PS), polybutadieneacrylic acid (PBAA), polybutadiene-acrylonitrile (PBAN),... 

Plasticized epoxy resins can be produced by reacting low molecular mass epoxy resins with dimeric fatty acids. These resins (e.g., Epikote 872, Shell) generally exhibit better substrate wetting than the unmodified epoxy resins. This reaction is, however, associated with the formation of ester bonds, and the resins therefore have a poor resistance to alkaline solutions. Instead of fatty acids, carboxy-functional polybutadiene-acrylonitrile elastomers can also be used to flexibilize epoxy resins. 

The abbreviations mean amino-, epoxy-, carboxyl- and non-functional end-capped polybutadiene-acrylonitrile copolymers, respectively, of the same molar mass and 18% AN content. The polarity of rubbers changes in the same order except for CTBN. Lower values of CTBN miscibility in comparison with ATBN and ETBN can possibly be caused by the great self-association effect of carboxyl groups through hydrogen bonding with the formation of high molar mass chains. 

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. 

Baccei (21) discloses polymerizable adhesive and sealant compositions having as an important ingredient urethane-acrylate-capped oligomers based on liquid hydroxyl-terminated polybutadiene or polybutadiene/ acrylonitrile copolymers. Properties associated with impact and thermal improvements are noted as well as the ability to cure adequately through the bondline gap. Model systems are largely triethylene glycol dimethacrylate based. Impressive adhesive performance properties are recorded. (Cf. Paper by Malofsky and Baccei in this... 

Reasonably early however in the development of telechelic polybutadiene/acrylonitrile, Brenner and Drake (22) showed that mercaptan- and carboxyl-terminated liquid polybutadiene/acrylonitrile did respond to electron-beam (1-5 megarads) and cure (2-3 seconds/pass) from the liquid to the solid state. The mercaptan polymer (3.1% RSH, 23% bound acrylonitrile, Mn 1700) cured more readily. CTBN as expected required 50-100% higher irradiation dosage levels. With both MTBN and CTBN-type products of higher acid content (6% vs 3%), gum rubber properties of 13.8-34.5 mPa were obtained with 60-100% elongation. The E-beam cures were carried out in air at ambient temperature. Thus, unformulated telechelic polybutadienes were shown to be substantive to cure in the presence of ionizing radiation. 

Pressure-sensitive adhesive masses, in one sense the opposite of structural adhesives (but also requiring permanence within their own performance definition), have been reported for both UV and E-beam processes where telechelic polybutadiene/acrylonitrile liquids are concerned. 

Perkins (27) published extensively on radiation curable pressure sensitive adhesives showing that permanent systems can be obtained if liquid hydroxyl-terminated polybutadiene/acrylonitrile were used with a selected acrylic interpolymer (e,g., 2-ethylhexyl-... 

Selected examples have been cited to demonstrate that areas of acrylic, anaerobic and radiation-curable adhesive developments have begun to consider telechelic polybutadiene/acrylonitrile liquids as useful formulating ingredients either in direct admixture or in the preparation of rubber-modified oligomers serving as an adhesive formulating base. These cited adhesive examples cover structural, semi-structural, gap-filling and pressure-sensitive types. 

Epoxy structural adhesives which employ carboxylic polybutadiene/acrylonitrile solid and liquid (CTBN) elastomers as modifiers have increased in number and proliferated in use since their introduction in the mid- 60 s. Such adhesive systems are now used in aircraft, electronics, automotive and industrial bonding operations. In the mid- 70 s, amine-reactive versions of the liquid polymers (ATBN) were issued, thereby offering another way to introduce rubber modification into a cured epoxy network. References are cited which provide detailed discussions of nitrile rubber, carboxylic nitrile rubber and both carboxyl- and amine-terminated nitrile liquid polymers (1-4). ... 

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