TY - JOUR
T1 - Nanocomposites of poly(ether ether ketone) with carbon nanofibers
T2 - Effects of dispersion and thermo-oxidative degradation on development of linear viscoelasticity and crystallinity
AU - Modi, Shriraj H.
AU - Dikovics, Kimberly B.
AU - Gevgilili, Halil
AU - Mago, Gaurav
AU - Bartolucci, Stephen F.
AU - Fisher, Frank T.
AU - Kalyon, Dilhan M.
PY - 2010/10/15
Y1 - 2010/10/15
N2 - Poly(ether ether ketone), PEEK, is a widely used engineering plastic that is especially suitable for high temperature applications. Compounding of PEEK with carbon nanofibers, CNF, has the potential of enhancing its mechanical and thermal properties further, even at relatively low CNF concentrations. However, such enhancements can be compromised by myriad factors, some of which are elucidated in this study. Considering that the dispersion of the CNF into any high molecular weight polymer is a challenge, two different processing methods, i.e., melt and solution processing were used to prepare PEEK nanocomposites with low aspect ratio carbon nanofibers. The linear viscoelastic material functions of PEEK nanocomposites in the solid and molten states were characterized as indirect indicators of the dispersion state of the nanofibers and suggested that the dispersion of nanofibers into PEEK becomes difficult at increasing CNF concentrations for both solution and melt processing methods. Furthermore, the time-dependence of the linear viscoelastic material functions of the PEEK/CNF nanocomposites at 360-400 °C indicated that PEEK undergoes thermo-oxidative cross-linking under typical melt processing conditions, thus preventing better dispersion by progressive increases of the mixing time and specific energy input during melt processing. The crystallization behavior of PEEK is also affected by the presence of CNF and degree of cross-linking, with the rate of crystallization decreasing with increasing degree of cross-linking and upon the incorporation of CNFs both for the solution and melt processed PEEK nanocomposites.
AB - Poly(ether ether ketone), PEEK, is a widely used engineering plastic that is especially suitable for high temperature applications. Compounding of PEEK with carbon nanofibers, CNF, has the potential of enhancing its mechanical and thermal properties further, even at relatively low CNF concentrations. However, such enhancements can be compromised by myriad factors, some of which are elucidated in this study. Considering that the dispersion of the CNF into any high molecular weight polymer is a challenge, two different processing methods, i.e., melt and solution processing were used to prepare PEEK nanocomposites with low aspect ratio carbon nanofibers. The linear viscoelastic material functions of PEEK nanocomposites in the solid and molten states were characterized as indirect indicators of the dispersion state of the nanofibers and suggested that the dispersion of nanofibers into PEEK becomes difficult at increasing CNF concentrations for both solution and melt processing methods. Furthermore, the time-dependence of the linear viscoelastic material functions of the PEEK/CNF nanocomposites at 360-400 °C indicated that PEEK undergoes thermo-oxidative cross-linking under typical melt processing conditions, thus preventing better dispersion by progressive increases of the mixing time and specific energy input during melt processing. The crystallization behavior of PEEK is also affected by the presence of CNF and degree of cross-linking, with the rate of crystallization decreasing with increasing degree of cross-linking and upon the incorporation of CNFs both for the solution and melt processed PEEK nanocomposites.
KW - Carbon nanofibers
KW - Nanocomposites
KW - PEEK
UR - http://www.scopus.com/inward/record.url?scp=77957880325&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77957880325&partnerID=8YFLogxK
U2 - 10.1016/j.polymer.2010.08.060
DO - 10.1016/j.polymer.2010.08.060
M3 - Article
AN - SCOPUS:77957880325
SN - 0032-3861
VL - 51
SP - 5236
EP - 5244
JO - Polymer
JF - Polymer
IS - 22
ER -