摘要:

The complex and important role of the propellant binder in solid-propellant rockets is described. The severe weight problems of space exploratrion cause high propellant performance to be of major concern in a highly competitive field. Binders contribute to performance, not only in terms of fuel value, but by being compatible with energetic components and by providing good mechanical properties. Both sterilization required for planetary landings and compatibility problems of new energetic oxidizers generate new requirements too stringent for existing binders; only binders composed essentially of saturated aliphatic hydrocarbon are predicted to be suitable. Several saturated-binder developments are in progress. The achievements of one of these programs, based on free-radical synthesis, are evaluated against the goals of the new binder.

ISSN:0022-233X    

DOI:10.1080/10601326908051834

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Saturated carboxy- and hydroxy-terminated hydrocarbon prepolymers and selected aziridine, epoxide, and isocyanate curing agents were evaluated with the purpose of preparing an elastomeric binder for solid propellants. Viscosities at a given molecular weight were higher for polyisoprenes than for polybutadienes and higher for carboxy terminated than for hydroxy terminated. Isocyanates showed much less side reactions in the presence of ammonium perchlorate than did the aziridines or the epoxides. The polymers had glass transition temperatures between -40° and -82°C when measured by density change. Differential thermal analysis indicated two secondorder transitions at about -64° and -38° for the saturated prepolymers and single transitions at about -75° and -90°C, respectively, for unsaturated prepolymers and polymers made from them. The polymers showed no tendency to crystallize. All of the polymers and propellants showed poor low-temperature behavior. The poor low-temperature properties have impeded acceptance of these materials by the industry. Partially saturated prepolymers show considerably improved low-temperature properties, indicating that saturated hydrocarbon chains are less flexible than the corresponding unsaturated one.

ISSN:0022-233X    

DOI:10.1080/10601326908051835

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

A series of functionally terminated poly(perfluoroalkylene oxides), a new class of curable, liquid, fluorinated polymers, has been prepared by the photopolymerization of perfluorooxydipropionyl fluoride, O(CF2CF2COF)2, and related perfluoroacyl fluoride monomers. Polymerization proceeds by ultraviolet-induced scission of CF2COF groups and coupling of the CF2—radicals thus formed. Polymer molecular weight and functionality increase with photolysis time. The acid fluoride-terminated polymers (Mn 1000–5000, functionality 2–5) are liquids possessing low Tg(about −60°C) and excellent, thermal stability. Other functional end groups (e.g., COOH, COOR, CH2OH, etc.) have been prepared using standard reactions.

ISSN:0022-233X    

DOI:10.1080/10601326908051836

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The functionality of a prepolymer, which is defined as the ratio of molecular weight to equivalent weight, is probably the most important single parameter that determines the properties of the cross-linked polymer network. The determination of prepolymer functionality therefore requires accurate knowledge of both number average molecular weight and equivalent weight. Ideally, a suitable prepolymer for propellant binder applications has terminal functionality (OH or COOH). Such a prepolymer theoretically has a functionality of 2.0. Because of uncontrolled chain termination reactions during the prepolymer synthesis, however, not all polymer chains have the desired functional end group. As a result, prepolymers generally have a distribution of functionalities, including onfunctional, monofunctional, and the desired difunctional prepolymer.

ISSN:0022-233X    

DOI:10.1080/10601326908051837

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0022-233X    

DOI:10.1080/10601326908051823

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor