Session: CS-19-01 Small Scale Mechanical Testing

Paper Number: 123048

123048 - Tensile Testing for Determination of Mechanical Properties of Recycled Pet-G Plastics 

Tensile Testing for Determination of Mechanical Properties of Recycled PET-G Plastics

Avianna Alvarez. Qin Ma, Janice McKenzie

Edward F. Cross School of Engineering 

Walla Walla University 

College Place, WA 99324, USA   

Abstract

            Tensile properties are important in the material world around us. It defines how a material can be used and what it requires to be practical. The data of tensile strength is commonly gathered by a stress-strain curve graph. Stress-strain curves depict the response patterns of a given material sample and are central to understanding the physics of the material.

Polyethylene terephthalate glycol (PET-G) has become one of the most widely used industrial thermoplastics due to its superior characteristics than its counterpart PET plastics as well as other common plastics in industrial such as ABS and PLA plastics. While PET-G offers similar strength and durability as ABS would do, its ease to work with like PLA plastics make it more flexible in applications. Moreover, the impact resistance of PET-G makes it suitable to design products for load-bearing applications. Because of the unique favorable characteristics, PET-G plastics has gained wide applications in the medical field for making medical devices such medical implants in addition to its many other common applications.

Loma Linda University, School of Allied Health Professions, Department of Orthotics & Prosthetics, the research and development team with the leadership of Professor Michael Moor and Professor Michael Davidson have been working towards the mission in developing low cost injection molding equipment to provide affordable, viable, and feasible O&P care for the most economically challenged individuals around the world. As part of their work, recycled PET-G plastics were melted and then thermoformed onto plaster molds under various conditions. Their mechanical properties are highly desirable.

In this study, tensile properties of the PET-G recycled plastic dog-bone coupons were obtained to be tested for modulus of elasticity, yield strength, tensile strength and ductility. ADMET eXpert 7600 equipped with MTESTQuattro Materials Testing Software was used as the testing machine. The load cell is 1000 lb. in capacity with cross-head movement, the vertical test space, capable of up to 41 inches. For consistent testing, ASTM standards were employed in preparation of the specimens and testing procedures. How does this compare? Typical properties are compared with standard commercially available counterpart PET-G plastics. It is found that the recycled plastics are significantly compromised in ductility but not the tensile strength in comparison with commercially available counterparts.

In addition, the role of extensometer was carefully investigated towards the property quantifications. It is found that while the role of extensometer may be important under certain circumstances in determining the modulus of elasticity, the offset yield strength, ductility measurement and the ultimate strength results are not affected. Numerical studies were performed to further investigate the role of extensometer so that a correction factor may be introduced for the more accurate measurement of the modulus of elasticity in case of testing without a facilitated extensometer. 

Presenting Author: Avianna Alvarez Walla Walla University

Presenting Author Biography: I am a second-year Mechanical Engineering Student at Walla Walla University. I love learning about the world around me and sharing that knowledge with others. I am 20 years old and enjoy many hobbies including camping, cooking, drawing, backpacking, and more! God has truly blessed me and I am so grateful for everything he has done!

Authors:

Avianna Alvarez Walla Walla University
Qin Ma Walla Walla University
Janice Mckenzie Walla Walla University