Chemistry Reference
In-Depth Information
The interlaminar toughness of the CFRC with semicrystalline matrix is lower
than that for the CFRC with pure amorphous matrix. This probably indicates a
high degree of brittleness of the former. The amorphization of the semicrystalline
matrix causes increase in G
1C
up to 200 J/m
2
for matrix PI:OI = 60:40 and to 1300
J/m
2
for matrix PI:OI = 90:10. The lower value of G
1C
as compared to that of
CFRC with a pure amorphous PI matrix is probably due to the presence of a
higher quantity of low molecular weight oligoimides in the PI matrix.
4. CONCLUSIONS
New semicrystalline polyimide matrices for composites were developed. During
the process of both thermal and chemical imidizations these binders can undergo
crystallization. Moreover, after melting they can also crystallize during cooling.
The crystallization process during cooling from the melt temperature of the R-
BAPB type matrix can be intensified by blending it with oligoimide of the same
chemical structure as that of the main PI matrix. It was shown that the higher the
oligoimide content in the mixture with the main PI matrix, the greater was the abil-
ity of the matrix to crystallize during cooling from the melt temperature. The ther-
mal stability of CFRC with the semicrystalline PI matrix increases by about 100
C
over that with the amorphous matrix. Moreover, the shear storage modulus of the
CFRC is approximately twice and its mechanical strength increases by 20-25%.
°
Acknowledgments
The financial support of this work by the Russian Foundation for Basic Research,
grant No. 01-03-32415, is gratefully acknowledged.
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