3D printing and characterization of hydroxypropyl methylcellulose and methylcellulose for biodegradable support structures

Thumbnail Image
Date
2020-01-01
Authors
Polampally, Prashant Ramkrishna
Major Professor
Advisor
Hantang Qin
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Authors
Research Projects
Organizational Units
Organizational Unit
Industrial and Manufacturing Systems Engineering
The Department of Industrial and Manufacturing Systems Engineering teaches the design, analysis, and improvement of the systems and processes in manufacturing, consulting, and service industries by application of the principles of engineering. The Department of General Engineering was formed in 1929. In 1956 its name changed to Department of Industrial Engineering. In 1989 its name changed to the Department of Industrial and Manufacturing Systems Engineering.
Journal Issue
Is Version Of
Versions
Series
Department
Industrial and Manufacturing Systems Engineering
Abstract

Additive manufacturing processes based on fused deposition modeling (FDM) typically use thermoplastic materials like ABS, PLA, or nylon to fabricate parts layer-by-layer. In order to build a part successfully with complex features such as pores or holes or irregular shapes, the build part requires support structures to hold the deposited material and to prevent the collapse of the finished parts before solidification. The support material acts as a sacrificial layer that should be easily removed later by chemicals/enzymes or broken by mechanical force. The current support materials used with FDM technology have challenges of poor dissolvability in chemical solutions and difficulty to be removed from the finished part. Also, these support materials are usually petroleum-based which has a negative impact on the environment. The goal of the project is to identify a suitable biomaterial for support structures that will eliminate the challenges of poor dissolvability and toxic waste generated by the currently available support materials in the market. This paper is focused on extrusion-based 3D printing process of thermoset biopolymers to fabricate support structures using Material Extrusion (ME). In this study, three biodegradable cellulose derivatives (i.e. MC A4M, HPMC K4M, and HPMC E4M) used with different degrees of substitution of the hydroxyl group. We investigated the effect of concentrations (8, 10, and 12% w/v) of all three cellulose derivatives on the rheological properties for understanding their printability. The rheological analysis revealed that all hydrogels exhibit shear-thinning properties with relatively low yield stress. At the same concentration, the apparent viscosity of HPMC K4M tended to be higher than HPMC E4M, followed by MC A4M. The effects of printing parameters (extrusion rate, nozzle diameter, and printing speed) were optimized to obtain the desired three-dimensional structures. The samples of 12% MC A4M and 12% w/v HPMC K4M showed higher complex shear modulus than other materials, which indicated higher rigidity and shape retention capacity of the printed parts. The ideal material for extrusion during printing and least deformation after printing was also observed for 12% MC A4M, which indicated a relationship between rheological properties and printability. The water dissolution of the MC and HPMC hydrogels allowed easy removal of the support structures from the build material. Biopolymers like MC and HPMC, when 3D printed as a support material via ME processes, help in moving closer towards sustainable manufacturing and a circular economy.

Comments
Description
Keywords
Citation
Source
Copyright
Fri May 01 00:00:00 UTC 2020