Enhanced engineering and biocidal polypropylene filaments enabling melt reduction of AgNO3 through PVP agent: A scalable process for the defense industry with MEX additive manufacturing

This study focused on the production of polypropylene (PP)/silver (Ag) composites via additive manufacturing. This study aimed to enhance the quality of medical-grade PP in material extrusion (MEX) three-dimensional printing (3DP) by improving its mechanical properties while simultaneously adding antibacterial properties. The latter can find extremely important and versatile properties that are applicable in defense and security domains. PP/Ag nanocomposites were prepared using a novel method based on a reaction occurring while mixing appropriate quantities of the starting polymers and additives, namely polyvinylpyrrolidone (PVP) as the matrix material and silver nitrate (AgNO 3 ) as the filler. This process produced three-dimensional (3D) printed filaments, which were then used to create specimens for a series of standardized tests. It was found that the mechanical properties of the nanocomposites were enhanced in relation to pristine PP, especially for the PP matrix with various loadings of AgNO 3 and PVP, such as 5.0 wt% and 2.5 wt%, respectively. The voids, inclusions, and actual-to-nominal dimensions also showed improved results. The 3DP specimens exhibited a more effective biocidal performance against Staphylococcus aureus than Escherichia coli, which developed an inhibition zone only in the case of PP with filler loading percentages of AgNO 3 and PVP at 10.0 wt% and 5.0 wt%, respectively Compounds possessing such properties can be beneficial for various applications requiring increased mechanical properties and biocidal capabilities, such as in the Defence or medical industries. • Development of multifunctional composites suitable for material extrusion additive manufacturing. • Evaluation of PVP as a reduction agent. • Silver Nitrate was the additive and medical grade polypropylene the matrix for the development of PP/Ag nanocomposites. • The mechanical properties were slightly improved (∼13.6% in the tensile test). • Sufficient antibacterial performance was found especially for the S. aureus bacterium.