Mechanical and nanomechanical properties of MWCNT/PP nanocomposite

The mechanical and nanomechanical properties of multi-walled carbon nanotube-reinforced polypropylene (MWCNT/PP) nanocomposite were investigated through tension tests (conducted on 2 wt% and 5 wt% specimens) and nanoindentation tests (conducted on 2 wt% specimens). In addition, the structural properties and topography of the nanocomposite were characterized by means of scanning electron microscopy (SEM) and Scanning Probe Microscopy (SPM), respectively. The results from the tension tests reveal an enhancement and a considerable scatter in the Young’s modulus and maximum stress of the MWCNT/PP nanocomposite for both MWCNT content. For the specimens with mechanical properties lower than the average values, the SEM and SPM images revealed poor dispersion and formation of large agglomerates. The hardness (as resistance to applied load) and Young’s modulus were mapped at 300 nm of displacement, for a grid of 70 ´ 70 μm2. Through projection, the resistance is clearly divided into 3 regions, namely the PP matrix, the interphase (region close to/between MWCNTs) and the regions of the MWCNT agglomerates. The resistance deviates from low values (few MPas) to 1.8 GPa. The present experimental study provides all necessary data for the model creation and validation of the MWCNT/PP nanocomposite

Mechanical and nanomechanical properties of MWCNT/PP nanocomposite

The mechanical and nanomechanical properties of multi-walled carbon nanotube-reinforced polypropylene (MWCNT/PP) nanocomposite were investigated through tension tests (conducted on 2 wt% and 5 wt% specimens) and nanoindentation tests (conducted on 2 wt% specimens). In addition, the structural properties and topography of the nanocomposite were characterized by means of scanning electron microscopy (SEM) and Scanning Probe Microscopy (SPM), respectively. The results from the tension tests reveal an enhancement and a considerable scatter in the Youngs modulus and maximum stress of the MWCNT/PP nanocomposite for both MWCNT content. For the specimens with mechanical properties lower than the average values, the SEM and SPM images revealed poor dispersion and formation of large agglomerates. The hardness (as resistance to applied load) and Young蒒s modulus were mapped at 300 nm of displacement, for a grid of 70 ( 70 �m2. Through projection, the resistance is clearly divided into 3 regions, namely the PP matrix, the interphase (region close to/between MWCNTs) and the regions of the MWCNT agglomerates. The resistance deviates from low values (few MPa) to 1.8 GPa. The present experimental study provides all necessary data for the model creation and validation of the MWCNT/PP nanocomposite

Materials characterisation and software tools as key enablers in Industry 5.0 and wider acceptance of new methods and products

Recently, the NMBP-35 Horizon 2020 projects - NanoMECommons, CHARISMA, and Easi-stress - organised a collaborative workshop to increase awareness of their contributions to the industry “commons” in terms of characterisation and digital transformation. They have established interoperability standards for knowledge management in characterisation and introduced new solutions for materials testing, aided by the standardisation of faster and more accurate assessment methods. The lessons learned from these projects and the discussions during the joint workshop emphasised the impact of recent developments and emerging needs in the field of characterisation. Specifically, the focus was on enhancing data quality through harmonisation and standardisation, as well as making advanced technologies and instruments accessible to a broader community with the goal of fostering increased trust in new products and a more skilled society. Experts also highlighted how characterisation and the corresponding experimental data can drive future innovation agendas towards technological breakthroughs. The focus of the discussion revolved around the characterisation and standardisation processes, along with the collection of modelling and characterisation tools, as well as protocols for data exchange. The broader context of materials characterisation and modelling within the materials community was explored, drawing insights from the Materials 2030 Roadmap and the experiences gained from NMBP-35 projects. This whitepaper has the objective of addressing common challenges encountered by the materials community, illuminating emerging trends and evolving techniques, and presenting the industry's perspective on emerging requirements and past success stories. It accomplishes this by providing specific examples and highlighting how these experiences can create fresh opportunities and strategies for newcomers entering the market. These advancements are anticipated to facilitate a more efficient transition from Industry 4.0 to 5.0 during the industrial revolution. © 2023The Workshop was supported by EU H2020 project NanoMECommons, GA 952869, CHARISMA, GA 952921, EASI-STRESS, GA 953219, and EsSENce COST ACTION CA19118. This article/publication is based upon work from COST Action EsSENce COST ACTION CA19118, supported by COST (European Cooperation in Science and Technology). Miguel A. Bañares, Raquel Portela, Nina Jeliazkova, Enrique Lozano, Bastian Barton and Iván Moya have received financial support from the EU H2020 project CHARISMA, GA n. 952921, Bojan Boskovic, Ennio Capria, Costas Charitidis, Donna Dykeman, Spyros Diplas, Gerhard Goldbeck, Marco Sebastiani, Elias Koumoulos, Silvia Giovanna Avataneo, Miguel A. Bañares, Raquel Portela, Anastasia Alexandratou, Athanasios Katsavrias, Fotis Mystakopoulos have received financial support from the EU H2020 project NanoMECommons, GA n. 952869, Nikolaj Zangernberg and Ennio Capria have received financial support from the EU H2020 project EASI-STRESS, GA n. 953219, Natalia Konchakova has received financial support from the EU H2020 project VIPCOAT, GA n. 952903, Costas Charitidis, Elias Koumoulos, and Spyros Diplas have received financial support from the EsSENce COST ACTION CA19118. All authors would like to specially acknowledge Anastasia Alexandratou, Athanasios Katsavrias and Fotis Mystakopoulos for their support in NMBP-35 joint Workshop organisation and documentation, and Steffen Neumann for his insights during the NMBP-35 joint Workshop discussions.Peer reviewe

A structure–activity approach towards the toxicity assessment of multicomponent metal oxide nanomaterials

<p>A structure–activity approach towards the toxicity assessment of multicomponent metal oxide nanomaterials</p&gt

Nanomechanical properties of plasma treated polylactic acid

In this work, a radio frequency discharged plasma generated in air atmosphere by pressure has been used to modify polylactic acid (PLA) surface. The results were evaluated through nanoindentation testing. Contact angle measurements revealed a gradual transition to a more hydrophilic state with increasing polarity after plasma treatment, while partial recovery to their untreated state during 10 day storage in air was evidenced. The results were evaluated through nanoindentation testing. All PLA samples exhibited an almost hard-like surface area where hardness and elastic modulus are enhanced. The activity of the plasma creates a higher cross-linking density within the material in the surface region. For higher displacements, both H and E tend to reach pristine PLA's values. Hardness values reveal surface hardening due to plasma treatment except for 180 s etching time, where hardness is slightly decreased possibly due to surface deformation. The change of H/E slope reveals the strengthening of oxygen plasma etched PLA with 180 s of etching time with increasing displacement.Scopu

In vitro cytotoxicity assessment of pristine and carboxyl-functionalized MWCNTs

The wide use of carbon nanotubes (CNTs) in consumer products, i.e. composites, coatings, food packaging, etc, raise concerns about the adverse effects that CNTs can induce in humans and environment. Yet, there is no global consensus regarding risks that CNTs may pose, while controversial evidence exists also on the toxic effects associated with chemical surface modification, a prerequisite for their incorporation in different matrices. Moreover, there is limited information available about the underlying mechanisms, especially when cells’ interactions with the nanomaterial is assessed by imaging techniques. The present study aims at evaluating the in vitro cytotoxicity of pristine and oxygen functionalized multi-walled CNTs (MWCNTs) by assessing cell viability and apoptosis in combination with scanning electron microscopy (SEM) observations of stabilised cells. Direct observation of adenocarcinoma human epithelial cells (A549) was performed after incubation with 12.5, 50 and 100 μg/ml MWCNTs, for 0.5, 1 and 3 h, simulating a real exposure scenario during an accident, taking into account industrial safety issues during the production and use of the nanomaterial. Functionalized MWCNTs induced higher time- and dose-dependent toxic effects as compared to pristine. The SEM observations revealed the damaging effect on the cell membrane, offering insights about the toxic mechanism that takes place. © 2020 Elsevier Lt

Additive manufacturing of hydroxyapatite–chitosan–genipin composite scaffolds for bone tissue engineering applications

Additive manufacturing holds promise for the fabrication of three-dimensional scaffolds with precise geometry, to serve as substrates for the guided regeneration of natural tissue. In this work, a bioinspired approach is adopted for the synthesis of hybrid hydroxyapatite hydrogels, which were subsequently printed to form 3D scaffolds for bone tissue engineering applications. These hydrogels consist of hydroxyapatite nanocrystals, biomimetically synthesized in the presence of both chitosan and L-arginine. To improve their mechanical properties, chemical crosslinking was performed using a natural crosslinking agent (genipin), and their rheology was modified by employing an acetic acid/gelatin solution. Regarding the 3D printing process, several parameters (flow, infill and perimeter speed) were studied in order to accurately produce scaffolds with predesigned geometry and micro-architecture, while also applying low printing temperature (15 °C). Following the printing procedure, the 3D scaffolds were freeze dried in order to remove the entrapped solvents and therefore, obtain a porous interconnected network. Evaluation of porosity was performed using micro-computed tomography and nanomechanical properties were assessed through nanoindentation. Results of both characterization techniques, showed that the scaffolds' porosity as well as their modulus values, fall within the corresponding range of the respective values of cancellous bone. The biocompatibility of the 3D printed scaffolds was assessed using MG63 human osteosarcoma cells for 7 days of culturing. Cell viability was evaluated by MTT assay as well as double staining and visualized under fluorescence microscopy, while cell morphology was analyzed through scanning electron microscopy. Biocompatibility tests, revealed that the scaffolds constitute a cell-friendly environment, allowed them to adhere on the scaffolds' surface, increase their population and maintain high levels of viability. © 2020 Elsevier B.V

Mechanical behaviour of a poydimethylsiloxane elastomer after outdoor weathering in two different weathering locations

The degradation of maxillofacial prosthetic elastomers that occur during physical weathering is usually responsible for the replacement of the prosthesis. In this study the mechanical behaviour of a polydimethylsiloxane (PDMS) elastomer was investigated, after 1 year outdoor weathering in two different weathering locations in Greece (Thessaloniki, Athens). The hypothesis investigated was that irradiation time did not affect the measured properties. Specimens (Elastomer 42) were prepared according to manufacturer's instructions and exposed to solar radiation for 1 year. Compression, tensile and nanoindentation tests were performed before and after the exposure. Compression and tensile data were also subjected to analysis of variance (ANOVA) and Tukey Post hoc tests at a level of α = .05. These properties were selected due to their clinical significance for fabrication and maintenance of a facial prosthesis. According to statistical analysis all the measured properties changed significantly after outdoor weathering. More specifically, most of the properties presented significant changes after six months of weathering. The observed changes also depended on the weathering locations. The hypothesis investigated was rejected. Material A became harder and the observed differences in the mechanical behaviour resulted from photo-degradation and hydrolysis that might occur due to weathering. The study also provides new information about maxillofacial prosthetics serviceability obtained from nanoindentation tests. © 2011 Elsevier Ltd. All rights reserved

Silver nanoparticles grown on cross-linked poly (Methacrylic acid) microspheres: Synthesis, characterization, and antifungal activity evaluation

Silver nanoparticles (AgNPs) exert profound physicochemical, biological, and antimicrobial properties, therefore, they have been extensively studied for a variety of applications such as food packaging and cultural heritage protection. However, restrictions in their stability, aggregation phenomena, and toxicity limit their extensive use. Hence, the use of functional substrates that pro-mote the silver nanoparticles’ growth and allow the formation of uniform-sized, evenly distributed, as well as stable nanoparticles, has been suggested. This study reports on the fabrication and the characterization of hydrophilic polymer spheres including nanoparticles with intrinsic antifungal properties. Poly (methacrylic acid) microspheres were synthesized, employing the distillation precipitation method, to provide monodisperse spherical substrates for the growth of silver nanoparticles, utilizing the co-precipitation of silver nitrate in aqueous media. The growth and the aggregation potential of the silver nanoparticles were studied, whereas the antifungal activity of the produced nanostructures was evaluated against the black mold-causing fungus Aspergillus niger. The produced structures exhibit dose-dependent antifungal activity. Therefore, they could potentially be employed for the protection and preservation of cultural heritage artifacts and considered as new agents for food protection from fungal contamination during storage. © 2021 by the authors. Licensee MDPI, Basel, Switzerland