The Role of Polyethylene Wax on the Thermal Conductivity of Transparent Ultradrawn Polyethylene Films

Xinglong Pan; Albert H P J Schenning; Lihua Shen; Cees W M Bastiaansen

doi:10.1021/acs.macromol.9b02647

The Role of Polyethylene Wax on the Thermal Conductivity of Transparent Ultradrawn Polyethylene Films

Macromolecules. 2020 Jul 14;53(13):5599-5603. doi: 10.1021/acs.macromol.9b02647. Epub 2020 Jun 15.

Authors

Xinglong Pan¹, Albert H P J Schenning^{1

2}, Lihua Shen^{1

3}, Cees W M Bastiaansen^{1

4}

Affiliations

¹ Laboratory of Stimuli-Responsive Functional Materials & Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Den Dolech 2, 5612 AZ, Eindhoven, The Netherlands.
² Institute for Complex Molecular Systems, Eindhoven University of Technology, Den Dolech 2, 5612 AZ, Eindhoven, The Netherlands.
³ Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, United States.
⁴ School of Engineering and Materials Science, Queen Mary, University of London, London E1 4NS, United Kingdom.

Abstract

Transparency and thermal conductivity of ultradrawn, ultrahigh-molecular-weight polyethylene films containing different contents of low-molecular-weight polyethylene wax (PE_wax) are explored from experimental and theoretical viewpoints. It is shown that the addition of PE_wax decreases light scattering in all directions, resulting from a reduction of defects while having little effect on crystallinity or chain orientation of ultradrawn films. In general, upon the addition of PE_wax, the thermal conductivity of ultradrawn films increases with the highest conductivity being 47 (W m^-1 K^-1) and subsequently decreases at higher concentrations. The thermal conductivity also depends on draw ratio and number-average molecular weight (Mn) of the films. A model is presented which correlates the thermal conductivity of the films with the draw ratio and Mn, enabling explanation of the experimental results. Hence, the thermal conductivity of ultradrawn polyethylene films can be predicted as a function of Mn and draw ratio.