1. Thermal Conductivity of Electrospun Polyethylene Nanofibers
Qian Zhanga, Jian Maa, Anthony Mayob, Leon Bellana, Richard Mub, and Deyu Lia
aDepartment of Mechanical Engineering, Vanderbilt University, Nashville, TN 37235
bDepartment of Physics, Fisk University, Nashville, TN 37208
Introduction
Polymers are normally thermal insulators. Recent results suggest that the thermal
conductivity of polymeric material is closely related to its microstructure, especially
molecular orientation. Electrospinning can produce well-aligned polymer fiber arrays with
ordered molecular chains within individual nanofibers. However, systematic studies
relating the electrospinning parameters, the resulted fiber structure and associated thermal
conductivity are still lacking.
We report on measurements of the thermal conductivity of electrospun PE nanofibers
prepared under different electric fields to explore the effects of electric field intensity on the
molecular alignment and resulted thermal conductivity. To correlate the relation between
structure and thermal conductivity, we conducted micro-Raman characterization on
individual nanofibers.
Measurement Setup
Fabrication and Measurement
Prepared polyethylene (PE) nanofiber for Raman and
thermal characterization.
Results
Raman spectra of PE powder and PE
nanofibers prepared at different voltages.
Nanofiber shrunk under electron beam irradiation and showed
significant structure change.
Summary
 Electrospinning exerts strong elongational force on polymer
chains, resulting in higher degree of molecular orientation and
enhanced level of crystallinity in fabricated nanofibers.
 The electrospun fibers show a general trend of higher thermal
conductivity with increasing fabrication voltage. The nanofibers
produced at the same voltage could show significant variation
due to ‘whipping instability’ in the electrospinning process.
We thank the financial support from National Science Foundation (Grant# CMMI-1462866). Jian Ma acknowledges financial support from the National Basic Research Program of China (2011CB707601, 2011CB707605) and the China Scholarship Council (CSC
201306090111). The research is in collaboration with Drs. Yunfei Chen, Zhonghua Ni and Hong Yi.
Thermal conductivity of fibers fabricated at 45 kV and
comparison with high crystalline PE.
Increasing thermal conductivity, chain alignment and
crystallinity with electrospinning voltage.
Acknowledgements
CMMI-1462866
Pt resistors
SiNx beams
SiNx membranes
Microdevice for thermal measurement
Electrospinning fabrication process and illustration of
polymer chains in amorphous and aligned status.