While fossil-based thermoplastics are the dominant raw materials in prosthetic and industrial applications, there is a general demand for reducing their use and replacing them with renewable, biobased materials.
Since a transtibial prosthesis sets strict demands on mechanical strength, durability, reliability, etc., which depend on the properties of the biocomposite used and also the additive manufacturing (AM) process, researchers with this study attempted to develop systematic solutions for prosthetic products and services by combining biocomposites using forestry-based derivatives with AM techniques.
Composite materials made of polypropylene (PP) reinforced with microfibrillated cellulose (MFC) were developed. The MFC contents—20, 30 and 40 percentage by weight (wt%)—were uniformly dispersed in the polymer PP matrix, and the MFC addition significantly enhanced the mechanical performance of the materials. With 30 wt% MFC, the tensile strength and Young’s modulus was about twice that of the PP when injection molding was performed. The composite material was successfully applied with an AM process, i.e., fused deposition modeling (FDM), and a transtibial prosthesis was created based on the end-user’s data.
A clinical trial of the prosthesis was conducted with successful outcomes in terms of wearing experience, appearance, and acceptance toward the materials and the technique.
Given the layer-by-layer nature of AM processes, structural and process optimizations are needed to maximize the reinforcement effects of MFC to eliminate variations in the binding area between adjacent layers and to improve the adhesion between layers, researchers found.
The study, Additive Manufacturing of Prostheses Using Forest-Based Composites, was published in PubMed.gov.