Chrysa Charou

Mrs. Chrysa Charou

orcid

Research Focus & Metrics

Academic Career Length

4Years (2023-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 July 2023 in Applied Sciences
Verified
Journal Article
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CDConstantine David
Constantine David
DSDimitrios Sagris
Dimitrios Sagris
Markos PetousisMarkos Petousis
Markos Petousis
Nektarios NasikasNektarios Nasikas
Nektarios Nasikas
AMAmalia Moutsopoulou
Amalia Moutsopoulou
NVNectarios Vidakis
Nectarios Vidakis
Both energy efficiency and robustness are popular demands for 3D-printed components nowadays. These opposing factors require compromises. This study examines the effects of seven general control variables on the energy demands and the compressive responses of polyamide (PA6) material extrusion (MEX) 3D printed samples. Nozzle Temperature, Layer Thickness, Orientation Angle, Raster Deposition Angle, Printing Speed, Bed Temperature, and Infill Density were studied. An L27 orthogonal array was compiled with five replicas. A total of 135 trials were conducted, following the ASTM D695-02a specifications. The stopwatch method was used to assess the construction time and energy usage. The compressive strength, toughness, and elasticity modulus were experimentally determined. The Taguchi technique ranks each control parameter’s impact on each response measure. The control parameter that had the greatest impact on both energy use and printing time was layer thickness. Additionally, the infill density had the greatest influence on the compressive strength. Quadratic regression model equations were formed for each of the response measures. The ideal compromise between mechanical strength and energy efficiency is now reported, with merit related to technological and economic benefits.

9 May 2023 in Nanomaterials
Verified
Journal Article
Open access
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Markos PetousisMarkos Petousis
Markos Petousis
Nikolaos MichailidisNikolaos Michailidis
Nikolaos Michailidis
Vassilis M PapadakisVassilis M Papadakis
Vassilis M Papadakis
Apostolos KorlosApostolos Korlos
Apostolos Korlos
NMNikolaos Mountakis
Nikolaos Mountakis
NVNectarios Vidakis
Nectarios Vidakis
The current research aimed to examine the thermomechanical properties of new nanocomposites in additive manufacturing (AM). Material extrusion (MEX) 3D printing was utilized to evolve acrylonitrile butadiene styrene (ABS) nanocomposites with silicon nitride nano-inclusions. Regarding the mechanical and thermal response, the fabricated 3D-printed samples were subjected to a course of standard tests, in view to evaluate the influence of the Si3N4 nanofiller content in the polymer matrix. The morphology and fractography of the fabricated filaments and samples were examined using scanning electron microscopy and atomic force microscopy. Moreover, Raman and energy dispersive spectroscopy tests were accomplished to evaluate the composition of the matrix polymer and nanomaterials. Silicon nitride nanoparticles were proved to induce a significant mechanical reinforcement in comparison with the polymer matrix without any additives or fillers. The optimal mechanical response was depicted to the grade ABS/Si3N4 4 wt. %. An impressive increase in flexural strength (30.3%) and flexural toughness (47.2%) was found. The results validate that these novel ABS nanocomposites with improved mechanical properties can be promising materials.

12 August 2023 in Ceramics International
Verified
Journal Article
Closed access
NVNectarios Vidakis
Nectarios Vidakis
AMAmalia Moutsopoulou
Amalia Moutsopoulou
Markos PetousisMarkos Petousis
Markos Petousis
Nikolaos MichailidisNikolaos Michailidis
Nikolaos Michailidis
CCChrysa Charou
Chrysa Charou
AAApostolos Argyros
Apostolos Argyros

25 May 2023 in Applied Sciences
Verified
Journal Article
Open access
PDF file
NVNectarios Vidakis
Nectarios Vidakis
Markos PetousisMarkos Petousis
Markos Petousis
NMNikolaos Mountakis
Nikolaos Mountakis
Vassilis M PapadakisVassilis M Papadakis
Vassilis M Papadakis
CCChrysa Charou
Chrysa Charou
PBPavlos Bastas
Pavlos Bastas
The industrial demand for functional filaments made of bio-sourced, biocompatible, biodegradable, and/or recyclable polymers and composites for material extrusion (MEX) 3D printing is continuously growing. Polylactic acid (PLA), the most popular filament, combines such properties, yet its reinforcement with low-cost, inert, and/or recycled fillers remains challenging. Herein, glass in three different micro/nano-forms was the reinforcement agent in PLA. Three different experimental tiers were elaborated by producing composite filaments with glass in powder, beads, and flake forms in various loadings to optimize the concentrations. A thermomechanical process, i.e., melt filament extrusion, was exploited. The composites were evaluated for their thermal degradation stability and composition using thermogravimetric analysis and Raman. MEX 3D printing was used to produce tensile, flexural, impact, and microhardness specimens, to quantitatively evaluate their mechanical response. Field emission scanning electron microscopy evaluation and fractography were carried out to depict fracture patterns of the specimens after their tests. All three glass types induced impressive reinforcement effects (up to 60% in flexural loading), especially in the flake form. The impact of the additional process cost through glass fillers implementation was also assessed, indicating that such composites are cost-effective.

25 September 2023 in Polymers
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Journal Article
Open access
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NVNectarios Vidakis
Nectarios Vidakis
AMAmalia Moutsopoulou
Amalia Moutsopoulou
Markos PetousisMarkos Petousis
Markos Petousis
Nikolaos MichailidisNikolaos Michailidis
Nikolaos Michailidis
CCChrysa Charou
Chrysa Charou
Evgenia DimitriouEvgenia Dimitriou
Evgenia Dimitriou
The goal of this paper is to investigate tungsten carbide (WC) as a reinforcement in the popular material extrusion (MEX) additive manufacturing (AM) procedure. The impressive characteristics of WC demonstrate its potential as a valuable additive for commonly used polymeric matrices in MEX 3D printing, offering reinforcement and stabilization properties. The mechanical properties of hybrid polymer/ceramic nanocomposites made up of various filler loadings (0–10 wt. %) of medical-grade polylactic acid (PLA) and WC were studied. The mechanical characteristics, structure, and thermomechanical properties of the resulting compounds were fully characterized following the respective standards. The fracture mechanisms were revealed with Scanning Electron Microscopy. Overall, a laborious effort was implemented with fifteen different tests to fully characterize the nanocomposites prepared. In comparison to the raw PLA material, the tensile strength of the 4.0 wt. % WC PLA/WC nanocomposite was improved by 42.5% and the flexural strength by 41.9%. In the microhardness test, a 120.4% improvement was achieved, justifying the properties of WC ceramic. According to these findings, PLA nanocomposites reach high-performance polymer specifications, expanding their potential use, especially in wear-related applications.

22 June 2023 in Polymers
Verified
Journal Article
Open access
PDF file
NVNectarios Vidakis
Nectarios Vidakis
Markos PetousisMarkos Petousis
Markos Petousis
AMAmalia Moutsopoulou
Amalia Moutsopoulou
Vassilis M PapadakisVassilis M Papadakis
Vassilis M Papadakis
MSMariza Spiridaki
Mariza Spiridaki
Emmanuel MaravelakisEmmanuel Maravelakis
Emmanuel Maravelakis
Herein, polytetrafluoroethylene (PTFE) is evaluated as a reinforcement agent in material extrusion (MEX) additive manufacturing (AM), aiming to develop nanocomposites with enhanced mechanical performance. Loadings up to 4.0 wt.% were introduced as fillers of polylactic acid (PLA) and polyamide 12 (PA12) matrices. Filaments for MEX AM were prepared to produce corresponding 3D-printed samples. For the thorough characterization of the nanocomposites, a series of standardized mechanical tests were followed, along with AFM, TGA, Raman spectroscopy, EDS, and SEM analyses. The results showed an improved mechanical response for filler concentrations between 2.0 and 3.0 wt.%. The enhancement for the PLA/PTFE 2.0 wt.% in the tensile strength reached 21.1% and the modulus of elasticity 25.5%; for the PA12/PTFE 3.0 wt.%, 34.1%, and 41.7%, respectively. For PLA/PTFE 2.0 wt.%, the enhancement in the flexural strength reached 57.6% and the modulus of elasticity 25.5%; for the PA12/PTFE 3.0 wt.%, 14.7%, and 17.2%, respectively. This research enables the ability to deploy PTFE as a reinforcement agent in the PA12 and PLA thermoplastic engineering polymers in the MEX AM process, expanding the potential applications.