Yazar "Popescu, Carmen-Mihaela" seçeneğine göre listele

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    Beneficial use of mussel shell as a bioadditive for TPU green composites by the valorization of an aqueous waste
    (Springernature, 2024) Sismanoglu, Sedef; Kanbur, Yasin; Popescu, Carmen-Mihaela; Kindzera, Diana; Tayfun, Umit
    Scientific studies have focused on environmentally friendly solutions as effective as the reuse of crop products owing to plastic-waste problems in recent years. This issue is the main driving force for upcoming academic research attempts in waste valorization-related studies. Herein, we integrated an aqua-waste, mussel shell (MS), as a bioadditive form into green thermoplastic polyurethane (TPU) green composites. Tuning of the MS surface was performed to achieve strong adhesion between composite phases. The surface functionalities of MS powders were evaluated via infrared spectroscopy and scanning electron microscopy (SEM) images. Composite samples were prepared by melt-compounding followed by injection molding techniques. It was confirmed by morphological analysis that relatively better adhesion between the phases was achieved for composites involving surface-modified MS compared to unmodified MS. Tensile strength and Young's modulus of surface-modified MS-filled composites were found to be higher than those of unmodified MS, whereas the elongation at break shifted to lower values with MS inclusions. The shore hardness of TPU was remarkably improved after being incorporated with silane-treated MS (AS-MS). Stearic acid-treated MS (ST-MS) additions resulted in an enhancement in the thermal stability of the composites. Thermo-mechanical analysis showed that the storage moduli of composites were higher than those of unfilled TPU. ST-MS additions led to an increase in the characteristic glass transition temperature of TPU. Melt flow index (MFI) of neat TPU was highly improved after MS loading regardless of modification type. According to the wear test, surface modification of MS displayed a positive effect on the wear resistance of TPU. As the water absorption data of the composites were evaluated, the TPU/AS-MS composite yielded the lowest water absorption. The silane layer on MS inclusion promoted water repellency of composites due to the hydrophobicity of silane. The results of the biodegradation investigation demonstrated that adding unmodified and/or modified MS to the TPU matrix increased the biodegradation rate. The test results at the end of a 7-week period of biodegradation with a soft-rot fungus implied that the composite materials were more biodegradable than pure TPU. Silane modification of MS exhibited better performance in terms of the characterized properties of TPU-based composites.
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    Effective use of olive pulp as biomass additive for eco-grade TPU-based composites using functional surface modifiers
    (Springer Heidelberg, 2023) Sismanoglu, Sedef; Tayfun, Umit; Popescu, Carmen-Mihaela; Kanbur, Yasin
    Olive pulp, which is formed 80% in the olive oil extraction process, attracts the attention of researchers with the zero waste project in Turkey. Our study aims to prove that olive pulp is not only a waste and can be used as a resource when used correctly as a filler in composite materials to provide not only durable but also shorter biodegradation times for polymer-based composite materials. The surface modification process with 3 different silanes containing epoxy, vinyl, and amino groups was applied to the surface of olive pulp (OP) to solve the problem of surface incompatibility with eco-grade thermoplastic polyurethane (TPU) matrix. The oil portion of OP was removed before silane treatments. Surface functions and thermal properties of both modified and unmodified OP powder samples were evaluated by FTIR, SEM, and TGA techniques, respectively. TPU/OP composites were fabricated using melt-compounding process, and mechanical, thermomechanical, thermal, melt flow, wear, biodegradation, and morphological properties of composites were reported. According to test results, TPU/VS-OP (vinyl silanized olive pulp) composite showed the highest hardness and wear resistance values among all composites. Additionally, silane modifications led to remarkable improvements for mechanical, thermal, thermomechanical, and melt flow properties of composites thanks to the enhancement of compatibility and interface adhesion between OP and TPU phases. It seems that VS-OP containing composite sample displayed the highest results in most of the examined results. It has been shown that the addition of unmodified and modified OP filler to TPU caused to level of the biodegradation of pure TPU, and as a result, environmentally friendly composites have been produced.
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    Reuse of black cumin biomass into beneficial additive for thermoplastic polyurethane-based green composites with silane modifiers
    (Springer Heidelberg, 2023) Sismanoglu, Sedef; Tayfun, Umit; Gradinariu, Petronela; Popescu, Carmen-Mihaela; Kanbur, Yasin
    Rich in protein, carbohydrates, and lignocellulosic, black cumin is a plant that is used in the treatment of many diseases and has antioxidant and anti-tumor properties. Apart from its use in medicine, black cumin is used as a filler in the production of new and eco-friendly eco-composites to reduce the environmental pollution caused by petroleum-based classical polymer composite materials. In this study, bio-based thermoplastic polyurethane (TPU) polymer was used as a matrix and black cumin unmodified and modified with 3 different functionalized group silanes, was added as a filler and mixed in a twin-screw extruder, and biocomposite materials in the form of dog-bones were produced by injection molding. Black cumin powders were analyzed by Fourier-transform infrared-attenuated total reflection (FTIR/ATR), field effect scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA), while the mechanical, tribological, morphological, thermal, thermo-mechanical, melt flow index, and biological properties of the produced biocomposites were characterized. According to the results obtained, it was seen that surface treatment of the black cumin with silane both improved the biodegradability and other properties of eco-composites. Among thermoplastic polyurethane-based eco-composites, surface modification of black cumin with 3-aminopropyltriethoxysilane had the lowest water absorption capacity of 8% and also the highest abrasion resistance and an improvement of 88.5%. It was observed that the eco-composite containing octyldecyl-modified black cumin had the lowest MFI value of 26, the best biodegradability among the surface-modified eco-composites, the tensile strength of 14.5 MPa, and the highest value compared to other eco-composites. Epoxy-silane modifier yields optimum results in terms of thermal and thermo-mechanical analysis.