Polyurethane elastomers containing polybutadiene and aliphatic diols: Polymerization and structure

Cohen, Dror; Siegmann, A.; Narkis, M.

doi:10.1002/pen.760270409

Cited by 13 publications

(6 citation statements)

References 15 publications

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“…By applying Beer-Lambert law to the IR spectrum of transparent liquid film prepared above, Figure 2 shows linear plots of absorbance of isocyanate group in IR region with time, indicating second order for the curing reaction, as had been reported by other workers (7) for urethane reaction between isocyanate and alcohol. From this we can infer the following rate equation:…”

Section: Resultssupporting

confidence: 69%

Studies on Curing of Polyurethane Propellant Binder System

Govindan

Athithan

1994

Propellants Explo Pyrotec

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Untersuchungen iiber die Aushartung von Festtreibstoffsystemen mit Polyurethan-Bindern Fur die Herstellung von Feststoff-Raketen werden Polyurethan-Treibstoffsysteme auf der Basis von hydroxyterminierten Polybutadienen als Binder verwendet. Die Verarbeitbarkeit des Treibstoffs wird bestimmt durch den Viskositatsgrad nach dem Entleeren des Mischers, was wechselweise abhangt von der Geschwindigkeit der Aushartungsreaktion zwischen Alkoholen und Isocyanat. Bei einem typischen Bindersystem bestehend aus Diol und Isocyanat wie bei Treibsatzen wurde mittels IR-Spektroskopie die Aushartungsgeschwindigkeit untersucht. Nonnalerweise werden kinetische Untersuchungen an einfachen Urethan-Reaktionen bei Einsatz der IR-Spektroskopie in Losung durchgefuhrt. In der vorliegenden Studie wurde das Fortschreiten der Reaktion bei einem nicht veridnderten Bindersystem in Abhangigkeit von der Zeit untersucht. Gleichzeitig wurden auch Viskositatsuntersuchungen durchgefuhrt, um die Geschwindigkeit des Viskositatsaufbaus mit der Zeit bei fortschreitender Reaktion zu testen. Bei beiden Untersuchungen wurden zwei verschiedene Phasen der Hartungsreaktion des Binders festgestellt. Die erste Phase brachte eine lineare Abnahme der Konzentration der Isocyanatgruppen gefolgt von einer zweiten Phase mit Tendenz zur Gleichgewichtseinstellung. Etudes de la cuisson de systemes de propergols solides a liant polyurethanePour la fabrication de fus6es h propergol solide, on utilise des systttmes de combustible polyurethane B base de polybutadibnes B terminaison hydroxy comme liant. La posibiliti de traitement du combustible est dCterminCe par le degrt de viscositC aprtts vidage du mtlangeur, qui depend rkciproquement de la vitesse de la rCaction de cuisson entre les alcools et l'isocyanate. Dans le cas d'un systttme de liant typique compose d'alcools et d'isocyanate comme dans les compositions de propergols, on a CtudiC les vitesses de cuisson au nioyen de la spectroscopie IR. Normalement, on effectue des Ctudes cin6tiques sur des rCactions urCthane en utilisant la spectroscopie IR en solution. Dans la prisente Ctude, on a analyst le dCroulement en fonction du temps de la reaction dans un systbme de liant non modifiC. SimultanCment, on a aussi realis6 des Ctudes de viscusitk pour tester la vitesse de 1'Ctablissement de la viscositk en fonction du temps au cours de la rkaction. Dans les deux Ctudes, on a constat6 deux phases diffkrentes de la reaction de cuisson du liant, la premibre phase conduisant B une diminution lintaire de la concentration des groupes isocyanates suivie d'une seconde phase tendant h Ctablir un Cquilibre. SummarySolid propellant rocket technology makes use of polyurethane propellant system based on hydroxy terminated polybutadiene as binder. Processability of the propellant is determined by viscosity build-up after unloading from the mixer, which in turn depends on rate of curing reaction between alcohols and isocyanate. For a typical binder system consisting of alcohols and isocyanate as in propellant composition, rate of curing ha...

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Section: Resultssupporting

confidence: 69%

Studies on Curing of Polyurethane Propellant Binder System

Govindan

Athithan

1994

Propellants Explo Pyrotec

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“…These substances belong to the formal class of polyurethane (PU) elastomers, especially those that recently contain hydroxyl-terminated polybutadiene (HTPB) (12)(13)(14). The HTPBbased polyurethane elastomers are superior to the common polyester-and polyether-based elastomers because they possess properties of lower water permeability, better stability in a moist atmosphere, higher electrical insulation, and lower glass-transition temperature (Tg) (15)(16)(17).…”

Section: Propellant Compositionmentioning

confidence: 99%

A Recovery Process for Spent Polyurethane-Based Propellants

Shiu

Yang

Yen

et al. 1995

ACS Symposium Series

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The valuable inorganic components-energetics and fuel-of solid propellants are successfully separated and recovered by using swelling and ultrasound. In this study, the inert polyurethane-based propellant is first comminuted in various solvents as swelling media, and an appropriate solvent is then selected. Subsequently an ultrasound induced cavitational reaction for interfacial treatment is performed with the use of a mild oxidant. Through the process, the polymer binders are partially degraded and the propellant network is destroyed, enabling inorganic and metallic constituents to be released and separated.To meet military need, solid composite propellants have been extensively developed and manufactured in the past. Following the end of the cold war, these large quantities of propellants from the demilitarization of missiles brought about the urgency of safe propellant disposal. While noted for their high energy release arid explosion, the spent propellants become hazardous wastes and need to be disposed with caution. In compliance to the Resources Conservation and Recovery Act (RCRA) and EPA regulations, the conventional and primary disposal method of spent propellant-open-pit burning-is no longer legal. These stringent environmental regulations and uprising pollution concerns have prompted the study of the recovery process for spent propellants.To recover the useful inorganic components from the spent propellant, the most common methods of breaking the polyurethane backbone macro-structure under vigorous conditions, such as thermal and hydrolytic cleavage, are not applicable. Currently, several techniques are actively being pursued by different groups. These include: aqueous maceration and extraction of propellant by Thiokol, cryogenic washout by General Atomic, and ammonia extraction at supercritical or near-supercritical conditions by Hercules. In addition to these, alternative methods leading to a mild recovery process are being sought.

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“…Oligomeric hydroxy‐terminated polybutadienes (HTPB) can potentially be used as a polyol component in the synthesis of more hydrophobic polyurethanes . HTPBs are also commercially available products used in composite propellants, adhesives, sealants, high‐quality binders for rubber crumb, potting materials and in electrical isolation, and gas separation equipment . HTPB‐based PUs represent an intermediate case with respect to polarity between rubber and usual PU elastomers.…”

Section: Introductionmentioning

confidence: 99%

“…The influence of the choice of the chain extender was mapped too. Previous investigations report on a zigzag pattern of for example decreasing and increasing tensile strength in case of elastomers based on aromatic diisocyanates. It has been observed that the mechanical properties are influenced by the number of carbon atoms in the chain extender .…”

Section: Introductionmentioning

confidence: 99%

Polyurethane elastomers based on amphiphilic poly(caprolactone)‐b‐poly(butadiene)‐b‐poly(caprolactone) triblockcopolyols

Fink

Eling²,

Pöselt³

et al. 2018

J. Polym. Sci. Part A: Polym. Chem.

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Hydroxyl-terminated poly(butadiene) (HTPB; M n 5 2100 g mol 21 ) was capped with 30 and 60 wt % of E-caprolactone to reach amphiphilic triblock copolymers in form of capped poly(butadiene) CPB. The former (CPB30; M n 5 3300 g/mol) is amorphous with a glass temperature of 256 8C. CPB60 (M n 5 4000 g mol 21 ) is semi-crystalline with a melting point of 50 8C and a glass transition at 247 8C. The CPBs, HTPB and polycaprolactone diol (M n 5 2000 g mol 21 ) were used as soft segment components in the preparation of polyurethane elastomers (PUE), using a 1/1 mixture of an MDI prepolymer and uretonimine modified MDI, and hard phase components in form of 1,3-propane diol, 1,4butane diol, and 1,5-pentane diol. CPB-based elastomers with 1,4 butane diol (8 wt %) show hard domains as fringed aggregates with a better connection to the continuous phase than the HTPBbased PUE. The soft segment glass transition temperature (T g ) is at 228 8C for HTPB-based PUE and at 243 8C for those of CPB. The tensile strength of the CPB30&60-based PUE is found between 20 and 30 MPa at an elongation at break of 400% and 550%, respectively.

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Polyurethane elastomers containing polybutadiene and aliphatic diols: Polymerization and structure

Cited by 13 publications

References 15 publications

Studies on Curing of Polyurethane Propellant Binder System

Studies on Curing of Polyurethane Propellant Binder System

A Recovery Process for Spent Polyurethane-Based Propellants

Polyurethane elastomers based on amphiphilic poly(caprolactone)‐b‐poly(butadiene)‐b‐poly(caprolactone) triblockcopolyols

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