Investigation of Solvent Vapor Smoothing on Surface Roughness and Mechanical Properties of 3D-Printed Polycarbonate (PC) Parts
Restricted (Penn State Only)
- Author:
- Abdulqader, Omar
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 24, 2025
- Committee Members:
- Ola Hamada Rashwan, Thesis Advisor/Co-Advisor
Zhezhen Fu, Committee Member
Brian Maicke, Professor in Charge/Director of Graduate Studies
Sheikh Fahad Ferdous, Committee Member - Keywords:
- Polycarbonate
PC
3D-Printing
Hot Vapor Smoothing
Fused Deposition Modeling
Additive Manufacturing
AM
Surface Roughness - Abstract:
- The Fused Deposition Modeling (FDM) process is now used more than ever. Its wide use can be attributed to its accessibility and ease of use. However, the quality of the surface roughness produced by FDM is one of its significant drawbacks. Conventional post-processing techniques, such as manual sanding and abrasive milling, fail to achieve consistent and uniform surfaces, especially when the 3D-printed parts are complex or have intricate geometries. Other chemical post-processing techniques, including manual painting and chemical immersion, have been reported as aggressive and hard to control, leading to poor dimensional accuracy and mechanical integrity of the treated 3D-printed parts. On the other hand, hot vapor smoothing has shown great potential in reducing the surface roughness of commonly used 3D-printed polymers, such as acrylonitrile butadiene styrene (ABS) and Polylactic acid (PLA). This study investigates the effect of hot vapor smoothing on 3D-printed PC samples made by FDM. The 3D-printed PC samples are exposed to the controlled vapor of three solvents: Acetone, Dichloromethane (DCM), Methyl Ethyl Ketone (MEK), and a mixture of MEK/Acetone. The results indicate that hot vapor smoothing can substantially reduce surface roughness. Among the solvents used, DCM stands as the highest performer in reducing the surface roughness by 88%, followed by Acetone at 82%. MEK was found aggressive and created surface cracks. However, the 50% MEK/ 50% acetone mixture successfully reduced surface roughness by 75%. Regarding the mechanical strength, the treatment conditions leading to the highest surface roughness reduction compromised the Ultimate Tensile Strength (UTS) of the treated samples by 9.3%, 17.1% and 13.1% for Acetone, DCM, and MEK/Acetone mixture, respectively. However, some samples treated with acetone and DCM achieved 78% and 82 % reduction in surface roughness, respectively, resulting in only a 1% reduction in UTS. Beyond tensile strength, hot vapor smoothing influenced other mechanical properties and dimensional accuracy. Young’s modulus decreased across all treatment conditions, indicating a reduction in stiffness. On the other hand, ductility, which was estimated by the % strain at break, increased in all cases. Additionally, average toughness values were estimated by calculating the area under the stress-strain curve. The results indicated improved toughness for acetone- and MEK/acetone-treated samples, while DCM-treated samples maintained toughness levels close to those of the control samples. In terms of dimensional accuracy, the length and width of the samples consistently decreased by a maximum of 0.3% and 0.18%, respectively, while the thickness slightly increased across all treatment conditions by 2%. Furthermore, the weight consistently increased across all treatments, with a maximum of approximately 2%, indicating the solvent diffusion into the 3D-printed samples. Differential Scanning Calorimetry (DSC) analysis was conducted. A slight effect on the glass transition temperature was observed, and no crystallinity was observed for the treated samples, which means the PC structure remains amorphous. These findings demonstrate that hot vapor smoothing is a viable post-processing technique for 3D-printed PC parts made by FDM, offering substantial surface roughness improvements with minimal impact on the mechanical and structural properties of 3D-printed PCs. Such Surface improvements can enhance the functionality of the 3D-printed PC components and expand their uses in various applications.