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- MakaleYalnız künye2024Scopus SJRQ2Evaluation of effect of boric acid on thermoplastic starch: Morphological, mechanical, barrier, and optical properties
Yoğurtçu, Hakan; Gürler, Nedim
In this study, starch was modified with different amounts of boric acid, and the degree of substitution of the synthesized compounds at different temperatures and times was determined by Fourier transform infrared (FTIR) and titration methods. The degrees of substitution in both methods showed similar tendency. Optimum conditions were determined, and thermoplastic starch (TPS) and boric acid (B) films were prepared by casting method using glycerol as plasticizer. The morphological properties of the films were studied by scanning electron microscope-energy dispersive spectrometry (SEM-EDS). According to the FTIR results, it was observed that the B-O and B-O-C stretching vibrations increased when the amount of boric acid increased. The tensile strength, water barrier (swelling capacity, solubility, and water vapor permeability), and optical properties of samples were investigated. The swelling capacity, solubility, and water vapor permeability of the films decreased with the addition of 0.5% boric acid to the starch, but the highest tensile strength was achieved. The tensile strength for TPSB0.5% increased compared to control group TPS. In addition, the film showed the highest transparency. Thermoplastic film containing 0.5% boric acid can be used as a packaging material due to its improved mechanical and water barrier. Highlights: The thermoplastic starch and boric acid composite were successfully produced. The presence of boric acid was confirmed by energy dispersive spectrometry (EDS). The degree of substitution was determined by two different methods. Transparency increased with the addition of boric acid. Tensile strength improved with boric acid content.
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İncele - MakaleYalnız künye2022Scopus SJRQ2Dielectric Biodegradable Biopolymer-Based Graphene Nanocomposites for Use in the Packaging Industry and Capacitor Application
Gürler, Nedim; Torğut, Gülben
In this study, polyhydroxyalkanoate (PHA) and polylactic acid (PLA)-Graphene (G) nanocomposite films were synthesized by taking different concentrations of G via the solution casting process, and their structural, mechanical, opacity, thermal and dielectric properties were examined for the first time. Scanning electron microscopy (SEM) was used for investigating surface morphology. Films containing graphene were more opaque than films without graphene. The incorporation of graphene into the polymer matrix improved the mechanical property. The tensile strengths of the control PHA/PLA film and the graphene-reinforced 1 %G-PHA/PLA nanocomposite films were 18.98 and 24.34 MPa, respectively. Thermogravimetric analysis results showed that PHA/PLA−G nanocomposites had good thermal stability below 300 °C. Considering the dielectric measurements, it is seen that the dielectric constant (έ) and dielectric loss (ϵ”) decreased with increasing frequency and less changed at higher frequencies. The developer feature of graphene is remarkable in both parameters. The electrical conductivity of PHA/PLA−G nanocomposites was also examined as a function of frequency at room temperature. As the amount of G increased from 1 %wt to 5 %wt, the conductivity of the composites increased.
AtıfScopus9WoS8OpenAlex11İncele - MakaleYalnız künye2021Scopus SJRQ2Graphene-reinforced potato starch composite films: Improvement of mechanical, barrier and electrical properties
Gürler, Nedim; Torğut, Gülben
In this study, PSG composite films were prepared by casting method by adding graphene (G) to glycerol plasticized potato starch (PS) films. The structure and properties of the composite films were investigated attenuated total reflectance Fourier transform infrared (ATR-FTIR), X-ray analysis (XRD), and swelling capacity, total soluble matter, transparency, tensile strength, and electrical conductivity. When the G content of PSG composite films increased from 0% to 1%, tensile strength increased from 1.035 MPa to 1.681 MPa, but decreased to 1.175 MPa in composite films containing 2% G. It also increased electrical conductivity when the G concentration increased. Also, the G layers are among the PS films and their swelling and solubility properties are reduced. With increased G concentration, the light transmittance decreased and the films were more opaque. These improvements can refer to the interface interaction between PS and G.
AtıfScopus43WoS35OpenAlex39İncele - MakaleAçık Erişim2018Scopus SJRQ3Experimental investigation of the tensile and impact properties of twill and twill derivative woven fabric reinforced composites
Özdemir, Hakan; Içten, Bülent Murat; Doğan, Akar
In recent years the use of woven composites in structural applications has increased rapidly due to the advantages it offers such as easy handling, dimensional stability, deep drawing shape-ability, enhanced toughness and increased impact resistance. Mechanical properties in textile composites are closely connected with the textile reinforcement's internal structure. This paper reports and discusses a study of the tensile and impact properties of the twill and twill derivative woven fabric reinforced composites. Tensile strength, modulus of elasticity and elongation at break values of the composites were found by tensile tests. In addition impact tests are performed on specimens of woven fabric reinforced composite laminates in order to measure impact strength and characterize damage mechanisms at diverse impact energies. The experimental results reveal that the average float length and weave interlacing coefficient, which are determined by weave pattern, significantly affect the tensile and impact properties of the composites. It is observed that 3/1 twill woven fabric reinforced composite showed the best performance in tensile tests along warp and weft directions. It is also observed that 3/1 twill woven fabric reinforced composite has the lowest impact strengths at the highest deflections; whereas, 3/3 twill woven fabric reinforced composite has the highest impact strengths at the lowest deflections.
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