Desenvolvimento de nanocompósito híbrido com propriedades virucidas e antibacterianas à base de polietileno de alta densidade (PEAD) reforçado com fibra vegetal piriquiteira (Cochlospermum orinocense) aditivado com nanopartículas de cobre (NPCu)

Abstract

The development of innovative materials capable of preventing the transmission, dissemination and entry of pathogens from viruses and bacteria into the human body are currently in the spotlight. Vegetable fibers, in general, are advantageous for use in composites because they have low density, low abrasiveness, low cost, are biodegradable and have a sustainable character, since their source is renewable. Seeking to optimize the properties of composites, the incorporation of metallic nanoparticles makes it possible to create new nanocomposites, especially those based on copper have been praised for their antimicrobial and virucidal effects. In this work, we highlight the development of a hybrid nanocomposite formed by the polymer matrix high density polyethylene (HDPE), reinforcement of the plant fiber piriquiteira (Cochlospermum orinocense) and copper nanoparticle (NPCu) in order to carry out the characterization and virucidal efficiency. and bactericidal. The first stage of the research was to carry out preliminary tests in order to determine the appropriate chemical pre-treatments for the fibers to be incorporated into the composites. For analysis and optimization of polymer composites parameters (HDPE / Fiber), the process variables initially analyzed were associated with fiber concentration, chemical treatment of mercerization with NaOH and extruder rotation. Statistical techniques were used as analysis tools and, in a first phase, complete factorial planning was used, followed by the modeling and optimization of these parameters associated with the proposition of regions of suitability of the process for the set of responses. After the two previous steps, the design of mixtures for hybrid nanocomposite was carried out with the parameters to the concentration of copper nanoparticles (NPCu) and (HDPE / Fiber) optimized. To obtain the polymer composites (HDPE / Fiber) and hybrid nanocomposites (HDPE / Fiber / NPCu) they were mixed and homogenized manually in a closed container and then poured into a single-screw extruder to form extruded wires and subsequently injected. The structural characterization of the in natura and treated fiber was performed using the X-ray Diffraction (XRD) technique, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetry (TG / DTG), the in order to relate the behavior of the mercerization treatment on the fiber. For the polymeric composites and hybrid nanocomposites, the structural characterization was performed using the techniques (FTIR), mechanical tests (Traction, Flexion and Impact Resistance). The virucidal and bactericidal efficiency for the developed nanocomposites were analyzed according to ISO 18184:2019 and ISO 22196 for plastic and non-porous surfaces respectively. The results of the chemical treatment on the fiber showed that a content close to 5% of NaOH is ideal for adhesion to the surface of the polymer matrix. In the response surface modeling it was possible to find the optimized composite with 18.63% fiber, 60 RPM rotation and 5.76% NaOH content, where it was possible to obtain the best statistically responses of the mechanical properties, which showed superior results of the polymer matrix. The nanocomposite developed in this work has a virucidal potential of 99.9% in 30min for the murine coronavirus (MNV-3) and human adenovirus (HAdV-2) viruses with enveloped and non-enveloped viral models respectively and with application for the manufacture of several virucidal surfaces, where they showed that the different proportions of fiber, NPCu and HDPE are efficient against viruses. For the antibacterial efficiency, the nanocomposites with a concentration of 10% of NPCu obtained 99.99% inhibition of the bacterium Listeria monocytogenes in 2 hours. The optimized composite (HDPE/Fiber) developed had a virucidal potential of 99.9% for the mentioned viruses, without the addition of the copper nanoparticle and suggests an industrial application of the final product.