04/07/2021
By Sokny Long

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a Master’s thesis defense by Shalmali Nitin Salunke on “Thermal Modeling of Nylon in Fused Filament Fabrication.”

Master’s Candidate: Shalmali Nitin Salunke
Defense Date: Friday, April 16, 2021
Time: 9 to 11 a.m. EST
Location: This will be a virtual defense via Zoom. Those interested in attending should contact shalmalinitin_salunke@student.uml.edu and committee advisor, amy_peterson@uml.edu, at least 24 hours prior to the defense to request access to the meeting.

Committee Chair (Advisor): Amy Peterson, Associate Professor, Plastics Engineering, University of Massachusetts Lowell

Committee Members:

  • Davide Masato, Assistant Professor, Plastics Engineering, University of Massachusetts Lowell
  • Jay Park, Assistant Professor, Plastics Engineering, University of Massachusetts Lowell

Brief Abstract:

Fused Filament Fabrication (FFF) is a form of additive manufacturing in which a polymeric filament is extruded through a heated nozzle and deposited in layers to print a structure. Due to layer-by-layer deposition, printed geometries undergo numerous heating and cooling cycles, as new heated layers are deposited over previously cooled layers. For semi-crystalline polymers, the cooled layers solidify and crystallize. The crystallization during solidification can cause volumetric shrinkage and residual stresses that affect the final part strength. Thus, temperature distribution throughout printed geometries plays a major role in determining crystallinity and final part strength. Temperature monitoring of FFF is challenging due to the limited ability to measure temperature at several locations or within printed structures without disturbing the printing process. Thermal modeling is an alternative method to estimate temperature distribution in printed parts. In this work, we present an approach to thermal modeling of FFF of Nylon, including prediction of crystallinity development. Crystallization kinetics were investigated using differential scanning calorimetry (DSC) for slow cooling rates and flash DSC for fast cooling rates. Experimental validation was performed by comparing crystallinity prediction vs. experimental results under different print conditions. The model predicts that the faster cooling rates associated with FFF will suppress crystallization. However, crystallization was observed experimentally for all print conditions, suggesting that the crystallization may be shear-induced and not thermally-induced. Thus, the proposed thermal model can be used to predict temperature distribution and thermally-induced crystallinity.

All interested students and faculty members are invited to attend the online defense via remote access.