Selective laser sintering of in-situ copper-modified polyamide

Abstract

Metals, ceramics, glass, and polymers are materials utilized in the design and manufacture of medical devices. Due to the wide variety of features they offer, such as biocompatibility, cost effectiveness, design freedom, and balanced mechanical properties, polymer materials are increasingly used to fabricate medical device components. Selective Laser Sintering (SLS) or Laser Powder Bed Fusion (LPBF) of plastic materials is an Additive Manufacturing (AM) technique where a bed of powder polymer or elastomer is sintered by laser with the subsequent solidification of the powder layer. Polyamide-based plastic materials are utilized to produce workable AM prototypes and end-use parts. Polyamide 12 (PA12), or Nylon 12, has 12 carbon atoms with a formula [-(CH2)11C(O)NH-]n and is a thermoplastic polymer that has excellent impact strength. PA12 is less sensitive to stress cracking than other nylon polymers and has quite low moisture absorption. Copolymerisation or different fillers can modify the physical, mechanical and other properties of polyamide (PA). Microorganisms may quickly colonize various polymer surfaces, especially in-house devices. The surfaces of these devices provide the opportunity to form biofilms that can facilitate the growth of infection and fever-causing microorganisms. The growth of microorganisms can also cause staining, discolouration, odour, and reduction of performance and material properties. As the public becomes more aware of hospital-acquired antibiotic-resistant diseases, alternative antimicrobials are often used in medical devices, equipment housings, and hygienic surface coatings. Copper (Cu) is proven to be an antibacterial agent in medical devices and is nontoxic to humans in low concentrations (Cervantes and Gutierrez-Corona, 1994). The antibacterial characteristics of Cu have made it a popular choice for food and medical device surfaces that are regularly handled. One advantage of SLS is the possibility of producing in-situ sintered materials from powder mixtures. This work evaluates the characteristics of in-situ SLS copper-modified black polyamide 12 (PA12/B) samples with the addition of 10 wt.% and 20 wt.% Cu as antibacterial agent. Roughness and morphological features of manufactured SLS surfaces, porosity, conductivity, mechanical properties and antibacterial characteristics of polymer-metal composite test samples are described in detail. It was shown that polyamide-copper antibacterial composites can improve the functionality of AM parts avoiding infections in users since pure Cu possesses antibacterial capabilities.