Browsing by Author "Yildiz, Umit Hakan"

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Citation - WoS: 14
Citation - Scopus: 19
Influence of Carbon Nanotube Inclusions To Electrical, Thermal, Physical and Mechanical Behaviors of Carbon-Fiber Abs Composites
(Springer Japan Kk, 2022) Akar, Alinda Oyku; Yildiz, Umit Hakan; Tirkes, Seha; Tayfun, Umit; Hacivelioglu, Ferda
Acrylonitrile-butadiene-styrene (ABS) terpolymer was compounded with short carbon fiber (CF) and carbon nanotube (CNT) using a micro-extruder followed by the injection molding process. Composite samples were fabricated with loading ratios of 20 wt.% CF and 0.1, 0.5 and 1.0 wt.% of CNT. Mechanical, electrical, thermo-mechanical, thermal, melt-flow, and structural investigations of ABS-based composites were conducted by performing tensile, impact, hardness, and wear tests, conductive atomic force microscopy (AFM), dynamic mechanical analysis (DMA), thermal gravimetric analysis (TGA), melt flow rate test (MFR), scanning electron microscopy (SEM) characterization techniques, respectively. According to mechanical test data of resultant composites including tensile and impact test findings, CNT additions led to the remarkable increase in tensile strength and impact resistance for CF reinforced ABS composites. The formation of synergy between CNT nanoparticles and CF was confirmed by electrical conduction results. The conductive path in ABS/CF composite system was achieved by the incorporation of CNT with different loading levels. SEM micrographs of composites proved that CNT nanoparticles exhibited homogeneous dispersion into ABS matrix for lower loadings. [GRAPHICS] .
Integration of Conductive Additives To Pla-Based Biodegradable Composite Films To Improve Their Electrical, Mechanical, and Physical Characteristics
(Wiley, 2025) Rakea, Aisha Muthana; Tirkes, Suha; Yildiz, Umit Hakan; Tirkes, Seha; Tayfun, Umit
In this study, Oltu stone powder (OS) and Fe3O4/mica-based conductive pigment (CP) were compounded with polylactic acid (PLA) to develop bio-based conductive films. Four different concentrations of 1%, 10%, 20%, and 30% of powders were applied to determine their optimal concentration in the PLA matrix. The mechanical, thermomechanical, electrical conductivity, melt-flow, and morphological properties of composite films were reported using the tensile, hardness, and impact tests, dynamic mechanical analyses test, linear four-probe method, and atomic force microscopy (AFM), melt-flow index measurements, and scanning electron microscopy methodology, respectively. According to tensile test results, tensile strength and modulus characteristics of PLA decrease with additive integration. However, the elongation value of PLA declined as OS and CP loadings increased. The maximum tensile performance was attained for composites filled with 20% of both CP and OS. The unfilled PLA's Shore D value rose by including OS and CP. At the same loading levels, carbon-based OS produced comparatively higher hardness values than CP, which comprised iron oxide and alumina silicate. AFM analysis revealed that both CP and OS inclusions caused enhancements in surface roughness as their filling amounts increased. In summary, composite samples exhibiting a 20% loading ratio of both OS and CP showed significantly improved mechanical and thermomechanical performances compared to other composites. Composite films with 1% additives have the potential to be applied in electrostatic packing. Additionally, 3D-printed components can be fabricated using composites for applications where appropriate mechanical resistance and electrical conductivity specifications are required.