Tailoring Physical Properties of Shape Memory Polymers for FDM-type Additive Manufacturing
Shape memory polymers (SMPs) have found applicability in biomedical settings as well as other uses that can take advantage of objects that can change shape upon exposure to stimulus. Integrating polymers with shape memory characteristics into additive manufacturing technologies such as fused deposition modeling (FDM™) can increase the number of applications this manufacturing platform can be utilized. Currently, polyurethane and polylactic acid (PLA) are two FDM™-compatible materials that possess shape memory properties. On their own these materials do not have tunable shape memory properties, namely shape recovery and shape fixation. The work presented here entails the development and characterization of two shape memory polymer material systems intended for FDM™-type additive manufacturing platforms. Here, two polymers with differing shape memory mechanisms (dual component and dual state) were combined in iterative ratios leading to material systems with tunable physical properties. Specimens fabricated via fused filament fabrication (FFF) were compared to those fabricated via injection molding. Dynamic mechanical analysis (DMA) was used to determine the critical thermal and rheological parameters as well as determine shape recovery temperature. Characterization of polymer crystallinity was determined via X-Ray diffraction (XRD) while scanning electron microscopy (SEM) was used to characterize the fracture morphology of impact test specimens. The shape memory properties were determined by deforming the specimens at room temperature and then recovering in an oven at a temperature corresponding with the maximum tan δ temperature. Of the material systems that could be evaluated by room temperature deformation, nearly 100% shape fixation and shape recovery was observed.
Quinonez, Paulina Aileen, "Tailoring Physical Properties of Shape Memory Polymers for FDM-type Additive Manufacturing" (2019). ETD Collection for University of Texas, El Paso. AAI27671604.