Title: Ultrafast Stiffening of Concentrated Thermoresponsive Polymer-Mineral Suspensions

Author(s): Kandy

Publication: Web Session

Volume: ws_S22_Kandy.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/28/2022

Abstract:
Extrusion-based 3D printing with rapidly hardening polymeric materials is capable of building almost any conceivable structure. Unlike polymeric materials, a lack of precise control of the extent and rate of solidification of cement-based suspensions is a major issue that affects their ability to 3D-print geometrically complex components and large-scale structures. This study provides guidelines to create designer compositions of polymer-mineral suspensions that utilize thermal triggers to achieve thermal latency and ultrafast stiffening – prerequisite attributes for 3D-manufacturing of topologically-optimized structural components. Here, we demonstrate a novel method for controllable-rapid solidification of concentrated polymer-mineral suspensions that contain a polymer binder system based on epoxy and thiol precursors as well as one or more mineral fillers like quartz and calcite. The thermally triggered epoxy-thiol condensation polymerization induces rapid stiffening of the hybrid suspensions (0.30 =???? = 0.60, ???? = volume fraction of solids), at trigger temperatures ranging between 50 °C to 90 °C achieving stiffening rates up to 400 Pa/s. The use of a carefully chosen nucleophilic initiator provides control over the activation temperature and curing rate thereby helping to achieve an adjustable induction period and excellent thermal latency. The current thermoresponsive formulations provide precise control over the engineered suspension compositions to achieve targeted, pre-, and post-curing material properties. The thermoresponsive suspensions can be utilized for extrusion-based 3D printing to produce overhangs, print highly stacked layers at a faster rate, and improve print fidelity.