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Öğe A comprehensive characterisation of wollastonite-filled low-density polyethylene composites(Springer, 2025) Tuna, Sibel; Sen, IbrahimIn this study, wollastonite (WOL)-filled low-density polyethylene (LDPE) composites were developed taking into account cost, environmental considerations and performance parameters that are essential for composite materials. For this purpose, LDPE composites containing 5, 10, 15 and 20 (wt%) WOL were produced by injection moulding process. When the results are examined, the effect of the addition of WOL can be seen in Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses. As a result of the microstructural analyses, it was observed that the WOL particles can be homogeneously distributed in the matrix, but there are interfacial voids. Accordingly, elongation at break (EB) and notched impact strength (NIS) values decreased, tensile strength (TS) values did not change significantly, while flexural strength (FS) and flexural modulus (FM) performance increased. The addition of WOL did not significantly change the melting and crystallisation temperatures (Tm and Tc) and the degree of crystallinity (Xc) of the composites, but had a positive effect on the temperatures at which the composites degraded by 5% (T5) and 50% (T50). When analysing the effect of WOL addition on the viscoelastic properties, an increase in storage modulus (SM) and loss modulus (LM) values was observed as the amount of WOL increased.Öğe Development of Carboxymethyl Cellulose and Graphene Filled Polypropylene Composites: Hybridization of Natural and Nanofillers(Wiley-V C H Verlag Gmbh, 2025) Tuna, Sibel; Sen, IbrahimPolymeric composites have become important in materials engineering thanks to their advanced properties and potential for versatile applications. In this study, the effects of reinforcing polypropylene (PP), a widely used thermoplastic with carboxymethyl cellulose (CMC), a natural additive, and graphene (Gr), a nanoadditive on its performance were investigated. While CMC offers advantages such as lightness and biodegradability, the goal of Gr is to achieve high mechanical and thermal performance in the composite. Using maleic anhydride as a compatibilizing agent improves the compatibility between the fillers and the matrix. Physical, structural, thermal, mechanical and morphological characterization of the injection-moulded composite structures revealed slight increases in density and hardness values, as well as enhanced crystallization behavior, thermal stability, and degree of crystallinity. The tensile and flexural properties generally improved with increasing filler content and microstructural analysis confirmed the good distribution and high interaction of the fillers in the matrix. Overall, hybrid structures incorporating CMC/Gr fillers in a PP matrix were identified as a promising alternative for multifunctional and sustainable engineering applications.Öğe Ecofriendly quince peel powder incorporated Polylactic acid biocomposite film(Sage Publications Ltd, 2024) Sen, Ibrahim; Eroglu, Murat; Severgun, Olcay; Kizil, DemetThis study aims to develop sustainable, renewable and biodegradable biocomposite films from environmentally friendly materials. For this purpose, completely biodegradable polymer composites were prepared by mixing polylactic acid (PLA) with a new source, quince peel (QP), by solvent casting method, and their structural, mechanical and thermal properties were examined. The tensile strengths of the composites prepared using QP in proportions varying between 5% (P5Q) and 30% (P30Q) by weight vary between 21.13 +/- 0.80 and 12.01 +/- 0.10 MPa, and their elongations at break vary between 11.33 +/- 0.38 and 4.08 +/- 1.06 %. As the QP contribution increased, the tensile strength and breaking elongation of these composites generally decreased, while the elastic modulus also increased. Among these composites, whose elastic modulus varies between 1040.00 +/- 140.01 and 811.33 +/- 13.31 MPa, it was determined that the elastic modulus (1040.00 +/- 140.01 MPa) of the 20% QP added composite (P20Q) was higher than the others. When the thermal analysis of PLA/QP films were examined, it was observed that the glass transition temperatures (Tg) were between 58.54 and 51.45 degrees C and the melting temperatures (Tm) were between 167.71 and 164.28 degrees C, and these temperatures generally decreased with increasing QP doping. When the T50 values, which represent the temperature at which 50% of the composite materials decompose, were examined, it was found that the QP-added ones were higher than the pure composites. While this value was 317.96 degrees C in pure PLA composite, T50 values varied between 327.92 and 340.80 degrees C depending on the varying QP ratios. According to the XRD results performed to evaluate the crystalline properties of PLA composites containing quince bark, the crystallinity of pure PLA was determined as 19.5% and the crystallinity of composites containing 5, 10, 20 and 30 wt % QP additives was determined as 19.3, 18.3, 16.4 and 14.6%, respectively.Öğe Effect of Olive Leaf Powder on Structural, Thermal, Mechanical, and Antioxidant Properties of Polylactic Acid Based Biocomposite Films(Wiley, 2025) Tuna, Sibel; Kizil, Demet; Sen, Ibrahim; Eroglu, MuratIn the present study, polylactic acid films containing olive leaves with different particle sizes and different additive ratios were characterized in terms of structural, thermal, mechanical, and antioxidant properties. XRD and SEM analyses showed that PLA films with olive leaf powder generally have an amorphous structure, whereas films with low filler ratios and fine particles exhibit higher crystallinity. Not so surprisingly, neither filler amount nor mixing time are making a big difference in the crystallinity or morphology of the surface. In the context of DSC analysis, a maximum variation of 2 degrees C in the glass transition temperature was observed. A comparable trend shift was observed between the Tg (glass transition temperature for DMA) values in the DMA analysis and the Tg (glass transition temperature for DSC) values in the DSC analysis. However, the change in the DMA analysis was more definitive. Antioxidant activity of the films was observed to increase with decreasing particle size of olive leaves added to polylactic acid and increasing additive ratio. Adding olive leaf powder to PLA and then looking at the effects on these aspects as mechanical, thermal, morphological, and antioxidant properties contributed to the evaluation of PLA as a potential additive for producing biodegradable polymers.Öğe Evaluation of the use and performance of natural filler based polypropylene/leonardite composites(Elsevier Sci Ltd, 2024) Sen, Ibrahim; Tuna, Sibel; Kurtlu, Meral AkkoyunThe use of polypropylene (PP), which has reached a considerably high level in the last century and is one of the polymers whose properties have been investigated and studied in much more detail with the use of various additives, can be obtained as composite structures with the use of both inorganic and organic additives, and the desired properties can be modified according to the desired purpose. In this study, it was aimed to evaluate the behavior of leonardite, a rich source of humic acid, with PP composite structures, whose performance with thermoplastic materials has never been investigated before, although there are studies on its use in different sectors. To evaluate the effects of different ratios of leonardite additives on PP polymer, the composites were prepared with a twin screw extruder, and the test specimens were produced using an injection molding device. Spectroscopic, density, microscopic, mechanical (tensile, impact, flexural), thermal and color analyses of composites containing leonardite at 0, 0.5, 1, 3, 5, and 10 wt% were carried out. As the amount of leonardite in the composite increased, a slight increase was observed in the density values of the composites, with a maximum of 4.7%. In microstructure analysis, a homogeneous distribution of the filler was observed in composites reinforced up to 1 wt%, while agglomeration occurred at higher rates. While the highest tensile strength and flexural strength values were found for the 5 wt% leonardite filled composite, it was observed that these values increased from 31.8 MPa to 32.7 MPa and from 32.84 MPa to 37.84 MPa compared to the pure PP, respectively. The highest Izod impact strength value was determined for the 10 wt% leonardite filled composite and an increase in this value was obtained from 2.47 kJ/m2 to 2.85 kJ/m2. The nucleation effect explains the decrease in supercooling temperature observed in the thermal analysis results. Furthermore, an increase of the thermal stability of PP/leonardite composite structures was demonstrated. When the color analysis results were examined, it was seen that the leonardite additive caused the color of the composite to darken, as expected.Öğe Investigations of the Nucleating Agent Effects on Polypropylene of Pumice from Three Distinct Areas in Türkiye(Mdpi, 2025) Ozdemir, Yasin; Atagur, Metehan; Sen, Ibrahim; Sever, KutlayThis study investigates the mechanical and thermal properties of polypropylene (PP) composites incorporating pumice, a naturally occurring porous volcanic rock with high SiO2 content, sourced from three regions in T & uuml;rkiye (Nev & scedil;ehir, Ala & ccedil;at & imath;, and K & uuml;tahya). Pumice was processed to particle sizes below 10 microns to maximize nucleating effectiveness, and composites were fabricated by melt compounding. The distinct mineralogical composition, porosity, and surface chemistry of the pumice samples enabled systematic evaluation of how regional variations influence crystallization and mechanical performance. A multi-analytical characterization approach, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and standardized mechanical tests (tensile, flexural, and impact), was applied. Results revealed that Ala & ccedil;at & imath; pumice at 0.1 wt% increased the impact strength of PP by about 11%, while maintaining stiffness. This demonstrates that pumice, unlike conventional fillers, can simultaneously enhance toughness and rigidity. Thermal analysis confirmed improved stability, with higher degradation onset and maximum decomposition temperatures observed in pumice-filled PP. DSC results indicated that certain pumice loadings promoted nucleation and increased crystallinity, while excessive amounts disrupted chain packing. SEM examinations confirmed uniform dispersion at low loadings, with agglomeration at higher levels reducing impact resistance. This work provides the first systematic demonstration of pumice powders as effective nucleating agents in PP, combining regional mineralogical diversity with measurable performance benefits. These findings indicate that pumice can serve as a sustainable, low-cost alternative to conventional nucleating agents, with potential applications in polymer components requiring improved toughness and thermal stability.Öğe Manufacturing and Characterization of Three Modified Vegetable Oil-Added Polylactic Acid Composites(Wiley, 2024) Sen, Ibrahim; Atagur, Metehan; Tuna, Sibel; Eroglu, Murat; Kurtlu, Meral Akkoyun; Sever, KutlayPolylactic acid (PLA) was modified with three types of modified vegetable oils (MVOs), which are the epoxidized soybean oil (ESBO), maleinized sunflower oil (MSO), and maleinized olive oil (MOO), at different weight fractions. A corotating twin screw extruder was used to produce composite materials by the melt-mixing process. The effect of MVO content, from 2.5% to 10%, on the morphology, mechanical properties, density, and water absorption was investigated in detail. The addition of ESBO and maleinized vegetable oils leads to a slight decrease in the density of PLA from 1.252 to 1.231 g/cm3. As the concentration of MVO in PLA increases, the amount of water absorption also increases, and the highest water absorption value was observed in P10MSO. The FTIR spectra of all concentrations of the MOO and MSO have two peaks at 1781 and 1861 cm-1, attributed to the C=O stretching which is related to maleic acid copolymerization. In general, the elastic modulus (EM) was slightly changed by the addition of MVOs to PLA, while the tensile strength (TS) decreased. Due to the plasticizing effect of MVOs, an increase in the Izod impact strength was obtained.Öğe Preparation and characterization of the Leonardite and Boric acid added Polylactic acid films for food packaging applications(Elsevier, 2024) Sen, IbrahimPolylactic acid (PLA), a biodegradable plastic, has begun to replace petroleum-based plastics used in thin film. According to the literature, various clays are used to develop PLA matrix film. In this study, PLA composite films containing specific proportions of Leonardite (LEO) and Boric acid (BOR) were prepared by casting method, and the physical, mechanical, thermal, barrier, and microstructure properties of these films were studied. As the amount of LEO in LEO and BOR/LEO added films increased, correspondingly increased the TS and EM values, while TR and MF values decreased, and the EB values fluctuated. As the amount of BOR increases in BOR added films, the increases and decreases in TS and EM values are similar, while the TR, MF and EB values decrease. In added films, the additive effect is clearly seen in the XRD patterns. While the addition of LEO significantly changed the surface color and opacity, BOR added films showed fewer changes in these properties. The Contact angle measurements demonstrated that, while the addition of BOR reduced the CA value, the addition of LEO partially increased it. The addition of BOR/LEO resulted in an increase in CA value because of the effects of LEO.Öğe Production and characterization of agricultural waste natural fiber-filled polylactic acid composites(Springer, 2025) Sen, Ibrahim; Sever, KutlayThe objective of this study was to obtain new composites containing polylactic acid (PLA) with artichoke stem (AP) at concentrations of 1%, 3%, 5%, 7%, and 10% by weight using a twin-screw extruder. The composites were created using biodegradable PLA and postharvest agricultural waste AP. The study aimed to determine whether these composites could be used. Thermal, mechanical, and morphological characterization of AP and these composites were performed. The findings of the study revealed that AP particles exhibited chemical and physical properties similar to other natural fibers. When incorporated into composites, these materials showed increased density and elastic modulus. However, decreases in tensile strength, elongation at break, and unnotched Izod impact were observed. Dynamic mechanical analysis revealed that PLA exhibited higher storage modulus (E ') values compared to AP-filled composites at 40 degrees C. In the differential scanning calorimetry analysis, while there was a slight fluctuation in the glass transition temperature (Tg) in the AP-filled composites, significant increases in the crystallinity degree (Xc) were observed when looking at the values of PLA. The results of the thermal gravimetric analysis showed that both Tmax and Ts values of the composite decreased as the AP content in PLA increased. Furthermore, SEM imaging of the composites containing P5AP clearly demonstrated the presence and distribution of AP particles within the PLA matrix.Öğe Structure, performance, and crystallization behavior of Turkey leonardite and raw kaolin added polylactic acid composite films(Sage Publications Ltd, 2024) Sen, IbrahimPolylactic acid (PLA) film composites filled with two clays, Raw Kaolin (KAO), an inorganic structure, and Leonardite (LEO), an organic structure, as well as KAO/LEO mixtures, were prepared via solvent casting method. The main aim of this research was to investigate both the individual and the synergetic effects of LEO and KAO; they are incorporated together into a PLA matrix. The influence of these fillers content on the morphological and structural characteristics of the composites was investigated by the DSC, TGA, FT-IR, SEM, XRD, color, haze, and opacity analysis. According to the TGA analysis, significant decreases in Tmax2 were observed with the addition of LEO in PLA. It is also seen in films with KAO/LEO that support this result. Utilizing the solvent casting method, two melting points were formed in PLA films. The P0 film has lower Tg, Tcc, and Tm1 values than other films. However, there were small changes in Tg and Tm2 values in all films. Up to 7.5% amount of LEO and KAO, the mechanical properties of the films improved. The 3L film exhibited the best mechanical properties. The filler materials used were mostly homogeneously distributed, according to the SEM analysis, and as the amount increased, agglomerations were observed in the fillings on the surface. The addition of LEO and KAO changed the surface color, visual appearance, and opacity significantly. The haze values of films are near 100. These film composites have been shown to improve many properties of the P0 film. Graphical Abstract
