# Constructing a Concentric GO Network via Rotational Extrusion for Synergistic Axial–Hoop Mechanics in Polymer Microtubes

## TL;DR

This paper introduces a new method to improve the mechanical properties of polymer microtubes using rotational extrusion and graphene oxide.

## Contribution

A rotational extrusion strategy is developed to create a concentric graphene oxide network in polymer microtubes, enhancing hoop mechanical properties.

## Key findings

- A concentric, interlocked graphene oxide network is formed in the circumferential direction of the microtube.
- The method achieves high compressive strength (0.54 MPa), improved bending resistance (30 N), and low-temperature impact toughness (0.33 J).
- The axial mechanical strength remains above 50 MPa, maintaining structural integrity.

## Abstract

Driven by societal and technological progress, the polymer tubing industry is increasingly focused on sustainable and biodegradable products, with polylactic acid (PLA)-based microtubes gaining attention for applications such as medical stents and disposable straws. However, their inherent mechanical limitations, especially under hoop loading and the brittleness of PLA, restrict broader use. Although two-dimensional nanofillers can enhance polymer properties, conventional extrusion only creates uniaxial alignment, leaving fillers randomly oriented in the radial plane and failing to improve hoop performance. To address this, we developed a rotational extrusion strategy that superimposes a rotational force onto the conventional axial flow, generating a biaxial stress field. By adjusting rotational speed to regulate hoop stress, a concentric, interlocked graphene oxide network in a PLA/polybutylene adipate terephthalate microtube is induced along the circumferential direction without disturbing its axial alignment. This architecturally tailored structure significantly enhances hoop mechanical properties, including high compressive strength of 0.54 MPa, excellent low-temperature impact toughness of 0.33 J, and improved bending resistance of 30 N, while maintaining axial mechanical strength exceeding 50 MPa. This work demonstrates a scalable and efficient processing route to fabricate high-performance composite microtubes with tunable and balanced directional properties, offering a viable strategy for industrial applications in medical, packaging, and structural fields.