Abstract
A significant challenge in conventional heat-shrinkable polymers is to produce controllable microstructures. Here we report that the polymer material fabricated by three-dimensional (3D) printing technique has a heat-shrinkable property, whose initial microstructure can undergo a spontaneous pattern transformation under heating. The underlying mechanism is revealed by evaluating internal strain of the printed polymer from its fabricating process. It is shown that a uniform internal strain is stored in the polymer during the printing process and can be released when heated above its glass transition temperature. Furthermore, the internal strain can be used to trigger the pattern transformation of the heat-shrinkable polymer in a controllable way. Our work provides insightful ideas to understand a novel mechanism on the heat-shrinkable effect of printed material, but also to present a simple approach to fabricate heat-shrinkable polymer with a controllable thermo-structural response.
Highlights
A significant challenge in conventional heat-shrinkable polymers is to produce controllable microstructures
We report the experimental observations of novel shrinkage and spontaneous pattern transformation of the polymer fabricated by 3D printing technique during heating, and the underlying mechanism is revealed by evaluating the internal strain related to phase transition of the polymer
The designed 2D lattices consisted of thin-walled polylactic acid (PLA) rings with an outer diameter of 24 mm, thickness of 0.4 mm and height of 1.5 mm
Summary
A significant challenge in conventional heat-shrinkable polymers is to produce controllable microstructures. We report that the polymer material fabricated by three-dimensional (3D) printing technique has a heat-shrinkable property, whose initial microstructure can undergo a spontaneous pattern transformation under heating. Heat-shrinkable phenomenon of polymer relies on the release of internal stress/strain from two different fabricating steps: (i) processing step and (ii) programming step. It is reported that macro internal stress can be generated in polymer without the effect of phase transition during 3D printing process, and can result in structural shrinkage and distortion, or even fabrication failure[22,23] at macroscale. We report the experimental observations of novel shrinkage and spontaneous pattern transformation of the polymer fabricated by 3D printing technique during heating, and the underlying mechanism is revealed by evaluating the internal strain related to phase transition of the polymer. A simple approach is proposed to fabricate heatshrinkable polymer which possesses controllable thermo-structural response and spontaneous pattern transformation under thermal stimuli
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