Dimensional crossover of heat conduction in amorphous Polyimide nanofibers

TL;DR

This paper investigates how heat conduction in amorphous Polyimide nanofibers transitions from three-dimensional to quasi-one-dimensional behavior, combining experimental observations with a theoretical model to explain the diameter dependence of thermal conductivity.

Contribution

It introduces a theoretical model based on random walk theory to describe heat conduction crossover in amorphous polymer nanofibers, linking structure to thermal properties.

Findings

Heat conduction transitions from 3D to quasi-1D in nanofibers.

The model explains diameter dependence of thermal conductivity.

It predicts an upper limit of thermal conductivity in amorphous polymers.

Abstract

The mechanism of thermal conductivity in amorphous polymers, especially polymer fibers, is unclear in comparison with that in inorganic materials. Here, we report the observation of across over of heat conduction behavior from three dimensions (3D) to quasi-one dimension (1D) in Polyimide(PI) nanofibers at a given temperature. A theoretical model based on the random walk theory has been proposed to quantitatively describe the interplay between the inter-chain hopping and the intra-chain hopping in nanofibers. This model explains well the diameter dependence of thermal conductivity and also speculates the upper limit of thermal conductivity of amorphous polymers in the quasi-1D limit.