01/15/2024
By Danielle Fretwell

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a Doctoral Dissertation Proposal defense by Nathalia Diaz Armas on: Elastomers: Investigation of Multimaterials for Innovative Applications.

Candidate Name: Nathalia Diaz Armas
Degree: Doctoral
Defense Date: Friday, Jan. 26, 2024
Time: noon to 2 p.m.
Location: ETIC 445

Committee

  • Advisor: Joey Mead, University Professor, Plastics Engineering, University of Massachusetts Lowell
  • Co-Advisor: Jinde Zhang, PhD, Plastics Engineering Department, University of Massachusetts Lowell
  • David Kazmer, Professor, Plastics Engineering, University of Massachusetts Lowell
  • Alireza Amirkhizi, Associate Professor, Mechanical Engineering, University of Massachusetts Lowell

Brief Abstract:
Elastomeric materials possess the unique ability to undergo large deformations when subjected to stress and subsequently return to their original shape upon stress removal. This study explores the use of elastomers in contemporary processes and applications.

In the first chapter, the focus is on multimaterial 3D printing of thermoplastic polyurethanes (TPU) of different hardnesses employing a unique printer that combines ram extrusion and filament deposition modeling (FDM). In this work it was found that the ram extrusion system enables printing with hardnesses as low as 50A, which is not viable for conventional filament-based systems. Moreover, combining TPUs materials with varying hardness levels offers unique advantages in merging both rigid and flexible materials. The use of TPUs provides good interfacial adhesion, as well as the 3D printing ability to manufacture complex geometries with rapid design changes.
In the second chapter, we study the printing of fully compounded elastomers in combination with thermoplastics. Printing fully compounded thermoset elastomers alongside thermoplastics presents significant challenges due to the contrasting processing conditions required for each material. This fusion becomes especially pertinent in applications where high temperatures or chemical exposures are prevalent, scenarios where the inherent properties of rubber-like materials, such as thermoplastic elastomers (TPE), are insufficient. Results of the bond strength between selected thermosets-thermoplastics during 3D printing are presented, studying the parameters influencing the adhesion.

In Chapter 3 a new manufacturing process involving elastomer braided composites for the development of a pneumatic-driven soft robotic actuator capable of providing haptic feedback to the fingers for teleoperation purposes is investigated. The utilization of braided structures embedded in a silicone rubber matrix allows for the customization of mechanical properties, and it preserves the much-needed attributes of flexibility, foldability, and impermeability to air. Through the manipulation of the braiding angle, multiple devices were fabricated, focusing on both mechanical properties and their effectiveness in transmitting haptic sensations to the user's finger.