Quantifying the Shape Memory Performance of a Three-Dimensional-Printed Biobased Polyester/Cellulose Composite Material

Abstract

A biobased composite material with heat-triggered shape memory ability was successfully formulated for threedimensional (3D) printing. It was produced from cellulose nanocrystals and cellulose micro-powder particles within a bioderived thermally cured polyester matrix based on glycerol, citric acid, and sebacic acid. The effect of curing duration on the material's shape memory behavior was quantified by using two thermo-mechanical approaches to measure recovery: (1) displacement in three-point bending and (2) angular recovery from a beam bent at 90°in a single cantilever setup. Extending curing duration increased the material's glass-transition temperature from-26°C after 6 h to 13°C after 72 h of curing. Fourier-transform infrared spectroscopy confirmed the associated progressive conversion of functional groups consistent with polyester formation. Slow recovery rates and low levels of shape recovery (22-70%) were found for samples cured less than 24 h. Those results also indicated a high dependence on the measurement approach. In contrast, samples cured for 48 and 72 h exhibited faster recovery rates, a significantly higher recovery percentage (90-100%) and were less sensitive to the measurement approach. Results demonstrated that once a sufficient curing threshold was achieved, additional curing time could be used to tune the material glass-transition temperature and create heattriggered 3D-printed products.

Biopolymeric additive manufacturing: The bidirectional interplay of synthetic and natural systems

“…Of particular note are shape memory polymers (SMP) which undergo a two stage cycle: first, programmed deformation to a temporary desired shape, and second, recovery of the original shape via external trigger [86]. With respect to the previously mentioned categories of biopolymers in Section 2.2, 4D printing has yielded many heat-activated structures, for example extruded cellulose composites, [87] extruded shape memory gelatin-based hydrogels with self-healing properties, [88] and hydroxybutyl methacrylated chitosan hydrogels from stereolithography [89]. Of course, heat activation is not the only structural trigger, for example extruded PHA/PLA composites have been made to activate structural change in response to changes in humidity [90].…”

Recent Advances in the Additive Manufacturing of Stimuli‐Responsive Soft Polymers

“…[7,[198][199][200] In extrusion-based printing, the successive printed layers bonded together by one of the two approaches: fused deposition modeling (FDM) and direct ink writing (DIW). [201][202][203][204] FDM utilizes temperature to liquefy the solid feedstock enabling the flow through the extrusion nozzle and deposition over the previously printed layer, [205][206][207][208][209] as illustrated in Figure 3A, which forms bonds during solidification. The combination of the FDM and thermo-responsive polymers (TRPs) is most commonly used to print dynamic structures.…”

4D Multimaterial Printing of Programmable and Selective Light‐Activated Shape‐Memory Structures with Embedded Gold Nanoparticles

“…Compared to T g of formulation 1 in DSC measurement, T g , DMA is a few degrees higher that could be caused by a relatively high heating rate in DMA measurement. Acquiring different values of T g for the same material when measuring by DSC or DMA is well known in the literature, [37][38][39] it is caused by the dependency of the measured value on the measurement conditions, such as heating rate and frequency. Additionally, when using DMA various methods can be applied to calculate the T g value: from E′, E″, or tan δ, each will result in a different value.…”