ORCID

https://orcid.org/0009-0007-8018-1970

Year

2025

Season

Fall

Paper Type

Master's Thesis

College

College of Computing, Engineering & Construction

Degree Name

Master of Science in Material Science & Engineering (MS)

Department

Interdisciplinary Studies

NACO controlled Corporate Body

University of North Florida. School of Engineering

Committee Chairperson

Dr. Jutima Simsiriwong

Second Advisor

Dr. Juan Aceros

Third Advisor

Dr. Daniel Santavicca

Fourth Advisor

Dr. Nelson Delfino de Campos Neto

Department Chair

Dr. Alan Harris

College Dean

Dr. William Klostermeyer

Abstract

ULTEM 9085 is a high-performance thermoplastic used in the fused filament fabrication (FFF) additive manufacturing process. It has found use in applications where mechanical strength, chemical integrity, and thermal stability are of paramount importance. In this thesis, the effects of process parameters, annealing, and weathering on the mechanical and dielectric properties of FFF ULTEM 9085 have been investigated.

The first part reviews existing research on how printing parameters such as nozzle temperature, chamber temperature, print speed, infill, and layer height affect the mechanical performance of FFF ULTEM 9085. Data from the manufacturer of commonly used ULTEM 9085 filament, Stratasys, has shown that the material behaves anisotropically: parts manufactured in the XY orientation show higher strength and ductility compared to parts manufactured in the YZ and ZX orientations. Low frequency dielectric testing has shown a degree of anisotropy in the dielectric properties.

The second part of this thesis experimentally examines the dielectric response of ULTEM 9085 over radio frequencies from 9 GHz to 15 GHz. This range of frequencies is relevant to radio communication, and therefore relevant to radome performance. Experimentation was completed using a WR-75 waveguide resonator and electromagnetic modeling. It was found that the XY orientation consistently produced the lowest dielectric constants across this frequency range compared to specimens produced in YZ and ZX orientations. Both the YZ and ZX orientations produced similar dielectric performance. The loss tangent was found to have little dependence on the print orientation. These trends in the dielectric constant are likely tied to the internal void structure which is dependent on the print orientation. Voids form in planes parallel to the material planes formed in the FFF process, and along the outer wall of the print in planes parallel to the external surface. The alignment of void planes relative to the applied electric field within the waveguide resonator is expected to affect the resultant dielectric properties.

The third part builds on the second by evaluating the effects of print orientation as well as infill density, annealing, and weathering on the radio frequency dielectric properties of FFF ULTEM 9085. The experiments were conducted using the same waveguide resonator as the second part. It was found that annealing and weathering both had limited effects on the dielectric constant of the produced parts. Similar to the second part, it was determined that the XY orientation produced the lowest dielectric constant compared to the XZ (YZ) orientation. It was also found that lower infill densities produce lower dielectric constants. Weathering by itself proved to have little effect on the loss tangent. However, annealing caused a decrease in the loss tangent. When specimens were both annealed and weathered, an increase in the loss tangent occurred.

Together, these studies proved a clearer picture of how FFF process parameters, annealing, and weathering affect the mechanical and dielectric properties of ULTEM 9085. While some factors were found to negatively affect the dielectric performance of ULTEM 9085, none of them pushed the dielectric properties outside the acceptable range. ULTEM 9085 has been proven to contain both excellent mechanical and excellent dielectric properties compared to other commonly used polymeric radome materials. ULTEM 9085 has high potential for use in naval radome applications.


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