/sup 1/H, /sup 19/F and /sup 11/B nuclear magnetic resonance characterization of BF/sub 3/:amine catalysts used in the cure of C fiber-epoxy prepregs
The chemical composition of commercial BF/sub 3/:amine complexes are variable and contain BF/sub 4//sup -/ and BF/sub 3/(OH)/sup -/ salts together with other unidentified highly reactive species. The BF/sub 3/:amine complexes, which are susceptible to hydrolysis, also partially convert to the BF/sub 4//sup -/ salt (i.e. BF/sub 4//sup -/NH/sub 3//sup +/C/sub 2/H/sub 5/) upon heating. This salt formation is accelerated in dimethyl sulfoxide solution and in the presence of the epoxides that are present in commercial prepregs. Commercial C fiber-epoxy prepregs are shown to contain either BF/sub 3/:NH/sub 2/C/sub 2/H/sub 5/ or BF/sub 3/:NHC/sub 5/H/sub 10/ species together with their BF/sub 4//sup -/ salts and a variety of boron-fluorine or carbon-fluorine prepreg species. Considerable variation in the relative quantities of BF/sub 3/:amine to its BF/sub 4//sup -/ salt was observed from prepreg lot to lot, which will cause variable viscosity-time-temperature prepreg cure profiles. It is concluded that the chemically stable and mobile BF/sub 4//sup -/ salt is the pre-dominant catalytic species, acting as a cationic catalyst for the prepreg cure reactions. During the early stages of cure the BF/sub 3/:amine catalyst converts to the BF/sub 4//sup -/ salt in the presence of epoxides, whereas the BF/sub 3/-prepreg species are susceptible to catalytic deactivation and immobilization.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5341106
- Report Number(s):
- UCRL-89627; CONF-840459-4; ON: DE84006139
- Resource Relation:
- Conference: 29. national SAMPE symposium, Reno, NV, USA, 3 Apr 1984
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMINES
COMPLEXES
BORON FLUORIDES
COMPOSITE MATERIALS
CURING
BORON 11
CARBON
CATALYSTS
EPOXIDES
FIBERS
FLUORINE 19
HYDROGEN
NUCLEAR MAGNETIC RESONANCE
STRUCTURAL CHEMICAL ANALYSIS
BORON COMPOUNDS
BORON ISOTOPES
ELEMENTS
FLUORIDES
FLUORINE COMPOUNDS
FLUORINE ISOTOPES
HALIDES
HALOGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MATERIALS
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
RESONANCE
STABLE ISOTOPES
360601* - Other Materials- Preparation & Manufacture