Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 36Citation - Scopus: 39Recent Developments of Colorimetric Mechanical Sensors Based on Polymer Composites(Royal Society of Chemistry, 2020) İnci, Ezgi; Topçu, Gökhan; Güner, Tuğrul; Demirkurt, Merve; Demir, Mustafa MuammerColorimetric mechanical (force, pressure, strain, and impact) sensors allow naked-eye visualization of existing structural deformations of a system occurring upon application of a mechanical action. The combination of mechanochromic materials with polymers offers a practical approach to designing and fabricating these sensors. Polymers as matrices can tolerate a wide range of forces and permits reusability of the sensors. On the other hand, mechanochromic materials provide unique colour properties depending on the type of mechanical action. They have also been frequently employed for the quantification of mechanical forces. As an example, non-centrosymmetric crystals are combined with polymers for sensing impact forces. Structures with photoluminescence and scattering and plasmonic resonances can be used to fabricate strain and pressure responsive composite materials, respectively. This study reviews recent advances in colorimetric mechanical sensor systems prepared using polymers and inorganic and organic mechanochromic materials working under a wide range of forces.Article Citation - WoS: 25Citation - Scopus: 28Colorimetric and Plasmonic Pressure Sensors Based on Polyacrylamide/Au Nanoparticles(Elsevier, 2019) Topçu, Gökhan; Güner, Tuğrul; İnci, Ezgi; Demir, Mustafa MuammerColorimetric stimuli-responsive nanomaterials have emerged as an eminent tool for sensor applications. Among this class of sensing elements, gold nanoparticle-based (Au NP) nanostructures are promising materials due to their plasmonic features. In this study, free-standing flexible polymeric films having intense optical response upon application of mechanical pressure were fabricated based on polyacrylamide (PAAm) and Au NPs. Pressure may cause plasmonic shift most probably due to the disassembly of the clusters from blue to reddish individual particles depending on the extent of pressure. Temperature, time, and extent of pressure were examined in terms of spectral change of Au particles. The sensor films depict working range up to 160 MPa, which shows minor change at elevated temperatures probably due to the stress induced crystallization of PAAm. For practical applications, a simple red-green-blue (RGB) space-based algorithm was presented for smartphone-assisted detection of applied pressure. Moreover, the PAAm/Au composite structure shows self-healing without any additive under ambient conditions even after divided into pieces. (C) 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 10Microstructures and Mechanical Properties of Graphene Platelets-Reinforced Spark Plasma Sintered Tantalum Diboride-Silicon Carbide Composites(IOP Publishing, 2019) Gürcan, Kübra; İnci, Ezgi; Saçkan, İbrahim; Ayaş, Erhan; Gasan, HakanGraphene nanoplates reinforcement (GNPs) TaB2-SiC composites were fabricated with Spark Plazma sintering (SPS) at 1850 degrees C with a-uniaxial pressure of 50 MPa and 10 min dwell time. Systematic investigation on the effect of GNP amount of densification, microstructural and mechanical properties (microhardness and fracture toughness) of the composites were presented. Density and hardness of composites decreased with the addition of GNP, while similar to 35% increase of fracture toughness value was obtained with GNP addition. The microstructural evaluation indicated that overlapped and agglomerated GNPs increased with an increasing amount of GNP in the composites and caused to decrease of density and hardness. On the other hand, GNP was retained in the composite form even with high process temperature (1850 degrees C) and cause toughening of composites with changing the fracture mode from transgranular to transgranular/intergranular fracture. GNP pull out, crack branching, crack bridging and crack deflection were observed as main toughening mechanisms.Article Citation - WoS: 21Citation - Scopus: 24Colloidal Films of Sio2 in Elastomeric Polyacrylates by Photopolymerization: a Strain Sensor Application(Elsevier, 2020) İnci, Ezgi; Topçu, Gökhan; Demir, Mustafa MuammerThin layer SiO2 colloidal films show angle-dependent coloration (iridescence) based on constructive interference, rather than absorption, without the existence of pigments. The transfer of thin layered colloidal film into a transparent elastomeric matrix maintaining its color may allow the fabrication of colorimetric strain sensors. In this study, trilayer SiO2 colloidal films were prepared by Langmuir-Blodgett deposition using a binary solvent system (chloroform/methanol) and this structure is successfully transferred into poly(ethylene glycol) phenyl ether acrylate elastomer via lateral capillary force. The resulting composite films exhibit iridescence depending on the particle size, therefore, film thickness as similar in mere colloidal films with a slight difference due to change in efficient refractive index (neff). Uniaxial extension of the composite film up to 50 % strain causes a remarkable linear shift in reflection signal from 568 to 496 nm. The change in thickness of the composite film accordingly intercolloidal distance normal to the application of mechanical stretching causes variation of the reflection of light.