1. Physical and Mechanical Properties of 3D Printed Polymers (ABS, PLA, and CopperFill)
Mason Strader1, Vivian Wang2
South-Doyle High School1, Farragut High School2
Rakesh R. Kamath3, Mallory Stevenson3, Hyojin Park3, Dr. Chris Wetteland3, Dr. Hahn Choo3
The University of Tennessee, Knoxville3
INTRODUCTION
Additive Manufacturing plays a crucial role in industry and manufacturing, a process in which 3D models are converted into readable STL and G-code files and then into physical models via the stacking of layers of material.
TESTING/METHODS
Tensile Strength Testing - A tensile force is applied uniaxially along the specimen, and as this increases, the specimen’s elongation is recorded, telling us the load it can withstand up until the point of failure
Scanning Electron Microscope (SEM) - A device which uses an electron beam and electromagnets (much in the same way an optical microscope uses light and a lens) in order to see an image in further magnification than an optical microscope (~ µ vs. ~0.2µ)
Thermogravimetric Analysis (TGA) - A method of analysis which reports the weight of a material as heat is applied, used to capture physical changes in the material, such as melting and evaporation, as increasing temperature is applied
Energy Dispersive X-Ray Spectroscopy (EDXS) - Through the detection of x-rays, the EDXS provided by a SEM gives information on the compositional makeup of a material
PRIMARY RESEARCH QUESTION
Through additive manufacturing, how can we determine our materials’ properties in regards to their microstructure and chemical composition ? How does this affect their individual strengths, weaknesses, and limits?
HYPOTHESIS
If the 3D printed polymers of ABS, PLA, and CopperFill underwent the same testing procedures, then the CopperFill would come out on top in terms of ultimate tensile strength, Young’s modulus, and all upcoming test results derived from the TGA and tensile strength testing.
PURPOSE OF RESEARCH
Understand the physical and mechanical properties of 3D printed polymers, and techniques used to find them
Translate and evaluate data from tensile-strength testing into a stress-strain curve
Learn the fundamentals of polymer 3D printing, SEM, and TGA equipment, as well as the implications of their operation
Study 1: Tensile behavior of different materials at 80% infill density: CopperFill, PLA, ABS (left to right)
Study 2: Tensile behavior of PLA with varying fill densities: 80%, 60%, 40% and 25% (left to right)
ANALYSIS & RESULTS
TENSILE STRENGTH TESTING
Study 1
Study 2
SCANNING ELECTRON MICROSCOPY (SEM)
ENERGY DISPERSIVE X-RAY SPECTROSCOPY (EDS)
= Copper
= Oxygen
THERMOGRAVIMETRIC ANALYSIS (TGA)
100% weight
80% weight
CONCLUSIONS
Through our research, we disproved our hypothesis, as the CopperFill (80% Copper/20% PLA) turned out to be the weakest in terms of elongation to failure, ultimate tensile strength, and finally engineering stress-strain maximums, while scoring the same as other samples in Young’s modulus. This can be found in the above graphs of study 1. This can be supported by the fact that polymers, being strongly bound to themselves, become weaker when a foreign material becomes embedded in the polymer, causing these bonds to be broken and less stable as the copper now blocks many of the atoms’ ability to join together.
In our second study, though not directly connected to our given hypothesis, we discovered that as fill density increases in a material (In this case, PLA), the material becomes stiffer and capable of withstanding more force before failure. The graphs depicting this can be found above in study 2. This is supported as any material that has more pores, voids, and/or empty spaces is bound to be weaker, as they provide to the instability of the material’s structure.
Acknowledgements:
This work was supported primarily by the ERC Program of the National Science Foundation and DOE under NSF Award Number EEC and the CURENT Industry Partnership Program. Other US government and industrial sponsors of CURENT research are also gratefully acknowledged.
References:
(1) (2) (3) cse.wwu.edu/amsec/ta-instruments-q500-tga