Study on The Impact Strength of 3D Printed Thermoplastic Polymers Subjected To Post-Printing Heat-Treatments

Abstract

Thermoplastic polymers can be softened and melted by heating which helps in molding them in different shapes. They are highly recyclable. Parts made from these thermoplastic polymers fabricated through 3D printing have reduced mechanical properties compared to those fabricated through injection molding. In this study, 3D printed samples manufactured using PLA and ABS filaments were subjected to impact testing. The samples were prepared by varying raster angle (0˚- 90˚) and build orientation (horizontal and vertical). Moreover, effect of post-printing heat treatment on the impact strength of samples was also studied. Samples printed in vertical orientation had the lowest impact strength and a flat fracture, owing to weak inter-layer bonding. Whereas impact strength was seen to increase with the increase in raster angle due to better adhesion between neighboring fibers. Poor interlayer tensile strength and void formation are some of the common defects associated with 3D printing. These defects are the main reason for the low impact strength of 3D printed parts. Heat-treatment of the samples 35-45 degrees above the glass transition temperature resulted in significant improvement in the impact strength of all the samples. The improvement is owed to improved adhesion between the neighboring layers and raster. The fractured surfaces are observed, and the defects are noted both with and without heat treatment. This work basically analyzes a post-processing heat treatment aimed at enhancing mechanical properties of 3D printed parts, while minimizing the associated defects. More specifically, purpose of this project is to study the impact strength of 3D printed thermoplastic polymers subjected to post printing heat treatment process and understanding the effect of heat treatment on structural changes