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  • Öge
    The effect of surface roughness on mechanical behavior of commercially pure titanium implants produced by selective laser melting
    (Institute of Science and Technology, 2018-06-07) Şenol, Seren ; Çimenoğlu, Hüseyin ; 506161422 ; Materials Engineering
    Implants produced by selective laser melting (SLM) have differentiating surface roughness caused by the process itself and applied surface treatments. Since surface quality and mechanical properties are critical parameters for implants and surface roughness is a known factor for stress concentration, it is aimed to investigate the effect of surface roughness on commercially pure titanium implants produced by SLM. Surface roughness is affected by several process parameters but this study focuses on the effect of position and orientation on surface roughness. First step is specified as determining the roughness measurement method ideal for this work. Therefore, 3 different roughness measurement methods as in confocal microscopy (CM), tactile profilometer and scanning electron microcopy (SEM) are compared by using the most common surface roughness parameter, Ra. Secondly, in order to determine the effect of position and orientation on surface roughness and determine roughness ranges across the build chamber, a build is designed with parts at 15 different positions with 6 different orientations that are specified considering the location of laser. Finally, for mechanical characterization, tensile bars are designed considering both the standards stated for tensile and fatigue test. Some parts are also post processed to see the post processing effect. For every position, 5 samples are subjected to tensile testing with 5 MPa pre-load until the part failure so that the average yield stress and UTS for every position are determined. Calculated average yield stresses are used to calculate fatigue test input. 5 stress levels are determined and 2 samples for low cycle, 3 samples for high cycle fatigue data are tested with load controlled, tension-tension fatigue test set-up with 60Hz frequency and R of 0.1. Surface finishing is differentiated by MPP and SB in addition to as-built form. Some samples are post processed with the standard post process of Materialise. Sand blasting and anodization are applied while for SB samples only sandblasting is applied. Then samples are tested to see pp effect on surface roughness and mechanical behavior. When the results are analyzed considering the roughness range and sample amount, the ideal roughness measurement method is determined as tactile profilometer because of its capability, repeatability, practical application and effectiveness if time and cost. The roughness range across the build plate is quantified for different positions and measured Ra values are in the range of 7 to 24 µm across the build plate. It is also concluded that at the right bottom side of the build chamber, and for the orientations perpendicular to the laser beam, surface roughness increases. Relation between Rz and thickness is specified and an equation is suggested to eliminate the effect of roughness on thickness. Since the thickness is effective on cross section calculations used for mechanical characterization, suggested equation is used to recalculate stress values measured with tensile and fatigue tests. Even though measured tensile and fatigue results indicate that increased surface roughness has a negative effect on tensile strength and fatigue life, recalculated tensile and fatigue results display no difference occurs with varying surface roughness. Therefore, it is shown that surface roughness has an effect on thickness hence has an effect on cross section that is affecting fatigue and tensile test results but it does not have a real significant effect on mechanical behavior of SLM printed cpTi parts.
  • Öge
    Partial Replacement Of EPDM By Devulcanized Rubber In Thermoplastic Vulcanizates Based On PP / EPDM: Effect Of Devulcanized Rubber, EPDM / PP Ratio, And Compatibilizer
    (Institute of Science and Technology, 2020-07-15) Pamukoğulları, Beste ; Özkal, Burak ; 521181002 ; Material Science and Engineering ; Malzeme Bilimi ve Mühendisliği
    In recent years, as the consumption frenzy increases in the world, the demands for materials that may be advantageous for both usage and mass production are increasing. Polymeric materials were born out of this need and replaced traditional materials. Unfortunately, the rapid consumption of polymeric materials brings with it the problem of waste management. When it comes to applications that require flexibility and durability, the first materials that come to mind are rubbers. But the structure that provides these features makes its recycling impossible. The production of rubber materials includes vulcanization, an irreversible reaction between elastomer, sulfur and other chemicals. Consequently, vulcanization procures cross-links in elastomer chains leading to the formation of a three-dimensional chemical network. The three-dimensional network of rubbers causes them to be solid and insoluble materials, so recycling of such materials is a current technological problem. One of the biggest challenges of 21st-century waste management is the recycling of rubber produced for various purposes. Approximately 70% of the rubber is used in tires, and the range of waste tires disposed of annually is about 800 million. Today, the most common approach to get rid of waste rubbers is to collect them in waste landfills. This leads to an accumulating scrap stock. This creates a fire hazard and also creates a favorable environment for rodents, mosquitoes, and other living things that cause health and environmental problems. Other approaches used to solve the problem of waste rubber are to grind the rubber into small pieces and re-use them in the production of low-performance products such as sports and play surfaces, floors, etc. or use rubbers as fuel. With these approaches, generally, low-quality rubber products are produced or additional pollution problems arise. It is stated in the literature that recycling is more efficient than other options. The breakdown of three-dimensional structures of rubbers is one of the most environmentally friendly options for recycling. The devulcanization methods are one of the most environmentally friendly recycling methods which allow the selective disintegration of sulfur-sulfur and carbon-sulfur chemical bonds formed as a result of vulcanization, without causing degradation in the polymer main chains of rubber. It is aimed to reuse the waste rubber formed after the devulcanization process applied by different methods such as chemical, ultrasonic, microwave, biological, thermomechanical, in the production of high-performance rubbers such as virgin rubber. In this study, recycled rubber obtained by thermomechanical and ultrasonic devulcanization of the waste of washing machine gaskets were use in the production of thermoplastic vulcanizates (TPVs). Devulcanized waste rubber was provided by the Fraunhofer Applied Research and Development Association. Thermoplastic elastomers are defined as a family of polymeric materials that can be processed and recycled in the same manner as thermoplastic materials but also exhibit several features associated with conventional thermoset rubbers. TPVs belong to this family and they are high-performance blends of thermoplastics and rubbers which prepared by dynamic vulcanization. In recent years, ethylene propylene diene rubber (EPDM) / polypropylene (PP) TPVs have attracted the attention of industry and academia with their commercial advantages, high performances and various application areas. EPDM / PP TPVs are widely used in automotive, electronic and electrical, construction and sports equipment, as they have excellent weathering, ozone and ultraviolet resistance and processing advantages. The devulcanization process is largely restricted in practice due to its high cost. Also, since the crosslinking structure of the rubber phase is required in EPDM / PP TPVs, it is not necessary to form the rubber phase from fully devulcanized rubber. Therefore, in this study, it was preferred to prepare TPVs by partially replacing the EPDM phase with devulcanized rubber. The purpose of this study is to produce EPDM / PP TPVs which devulcanized washing machine gaskets wastes are partially replaced with the EPDM phase without causing a serious change. EPDM phase in TPVs, in which 5%, 10%, and 20% of EPDM is replaced by devulcanized EPDM, was prepared using Banbury, two roll mill, and grinding devices, respectively. Then EPDM / PP TPVs are prepared by using twin-screw extruder with EPDM:PP ratios of 90/10 and 85/15 by weight. In addition, 2% and 5% by weight of maleic anhydride grafted polypropylene (PP-g-MA) was added to examine the effect of the compatibilizer in EPDM / PP TPVs. Briefly, in this study, the effect of partial replacement of EPDM with devulcanized waste EPDM replacement at different rates, the use of compatibilizers in EPDM / PP TPVs, and the effect of two different EPDM: PP weight ratios on EPDM / PP TPVs were investigated. To achieve this goal, formulations were developed, samples were manufactured, and their properties such as mechanical, physical, thermal, morphological, and aging were tested. The properties of the produced EPDM / PP TPVs are compared with the TPVs used in commercial products. We hypothesize that the devulcanized EPDM waste can be replaced with EPDM in EPDM / PP TPVs without a serious change in TPVs properties and have appropriate properties with commercial TPVs properties. This will create a remarkable, environmentally friendly approach for rubbers that are difficult to recycle.
  • Öge
    Investigation of the electrochemical co2 reduction mechanism on tin electrodes
    (Fen Bilimleri Enstitüsü, 2020) Yılmaz, Tuğçe ; Ürgen, Mustafa Kamil ; 633383 ; Malzeme Bilimi ve Mühendisliği
    In today's world, one of the biggest concern is climate change. Even though fossil fuels are started to replaced by renewable energy sources in recent years, this solution turned out to be not sufficient to decrease the accumulated CO2 in the atmosphere Increased human population and energy demand escalated the rate of CO2 emission with a higher rate than environmentally friendly energy sources. The released CO2 gas to the atmosphere by human activities is the main factor causing climate change. The increased amount of CO2 in the atmosphere causes a greenhouse effect that led to an increment in temperature. Thus, the studies concentrate on the CO2 conversion and storage methods to get rid of the excess CO2 in the atmosphere. The conversion of CO2 is not only useful to eliminate the CO2 gas in the atmosphere but also the products of this conversion is used as a raw material to produce valuable materials. There are various methods for the conversion of CO2 such as chemical, thermochemical, electrochemical, biochemical, photochemical, and etc. Among these methods electrochemical CO2 reduction method has numerous advantages such as no need for heating or pressure, harmless reactants, the possibility to have a carbon- neutral chemical production by supplying energy from renewable energy sources, and convenience to scale-up. Electrochemical CO2 reduction is a method in which a CO2 is reduced on an electrode surface acts as a catalyst. The typical setup for this process involves a cell divided by a proton exchange membrane. The counter electrode and working electrode are located on different sides of the cell. While CO2 is reduced to various chemicals by taking + electrons and H , besides the hydrogen evolution reaction on the working electrode; water-splitting reaction occurs on the counter electrode. There are many products that can be produced by electrochemical CO2 reduction and their formation potentials are close to each other. In addition, CO2 is a highly stable molecule due to its linear molecular structures. These two conditions make the use of a catalyst inevitable. The metal catalysts capable of reducing CO2 are grouped according to their selectivity to specific products. These metals and the products selectively formed on them are Pb, Hg, Tl, In, Sn, Bi, Cd − formate, Au, Ag, Zn, Pd, Ga – CO, Cu − alcohols and hydrocarbons. The optimal binding energy between the catalyst surface and the key intermediate to produce a certain product led to high selectivity. The aim of this study is to produce selectively formate because of its high energy density and economical value, and its nontoxic nature. Among the metals that are selectively produced formate Sn stands out because of its relatively low price, high availability, innocuousness, and most importantly high selectivity towards formate. Even there are numerous studies published regarding design highly selective Sn-based catalyst to produce formate, a few of them discourse the mechanism providing the high selectivity. However, to design a highly selective and efficient catalyst, one should understand the factors favoring formate production. Thus, understanding the mechanism will be a breakthrough in electrochemical CO2 reduction. In this study, the mechanism of electrochemical CO2 reduction to formate on the Sn electrode is investigated. At first, the reliable setup was built-up to have replicable and trustworthy results. To achieve the reproducibility, adjustment of the position of the reference electrode and the working electrode with respect to the membrane, stabilization of temperature, the distance between the counter and working electrode, and anode area were done. The working electrode was masked to have an area of 4 2 cm . However, the results were not reproducible. Following this, the annealing at 150, 180, and 200oC and anode area studies were done. As a result, the annealing has no significant effect on faradaic efficiency in this study. The faradaic efficiencies obtained on 4 cm2 were not reproducible, but when the electrode area was decreased to 2 cm2 results were reproducible. The increased counter electrode to working electrode area ratio and the more similar sizes of the electrode and membrane, ease the charge transfer and resulted in uniform charge distribution. Once the reliable setup is achieved, a cyclic voltammetry analysis was done on the pure Sn electrode in CO2 saturated 0.1 M KHCO3 electrolyte with pH 6.8. As a result, the reduction peak of tin oxide appeared at 1.0 V vs. Ag/AgCl, and in the literature, the electrochemical CO2 reduction experiments were done at more cathodic potentials. However, there are many studies indicating that the oxide layer on the tin surface is the key factor governing the high selectivity for formate. To clear up this contradiction, the longtime electrochemical CO2 reduction experiment was designed to understand the effect of tin oxide on selectivity towards formate. In this experiment, the formate production rates are detected for every ten minutes. The results revealed that in the first ten minutes the produced formate amount was almost 4 times higher than the remaining time intervals. This could be concluded as after the initial reduction of tin oxide the formate production rate decreased dramatically. Thereafter, 6 different polarization experiments were conducted on pure Sn electrodes to have a better understanding of the relationship between the tin oxide and CO2 reduction reaction. In the beginning, the pure Sn electrodes were polarized from open circuit potential to -2 V vs. Ag/AgCl repeatedly until the polarization curves no longer changed. Firstly, this process was done in Ar saturated 0.1 M KHCO3 electrolyte with pH 8.5. The resulting curve preserved its oxide peak, however, it was slightly reduced. When the experiment was repeated in CO2 saturated 0.1 M KHCO3 with pH 6.8, the oxide was greatly reduced. This contrast between two experiments might be originating from the differences in CO2 presence or pH of the electrolytes. Thus, the final experiment was done in H2SO4 added 0.1 M KOH which has a pH of 6.8 but there was no CO2 or even HCO3- in the electrolyte. The eventuated curve preserved its oxide peak, and that was more similar to polarization curves obtained in Ar saturated 0.1 M KHCO3 than the CO2 saturated 0.1 M KHCO3. However, it is worth noting that after the first cycle the oxide is reduced even less than the Ar saturated 0.1 M KHCO3. The second set of polarization experiments was designed to reduce the tin oxide electrochemically before the polarization. At first, the pure Sn electrodes were reduced at -1.8 V vs. Ag/AgCl for 15 minutes to give enough time to have a full reduction and simulate the real experimental conditions. Then, the polarizations were started at -1 V rather than to open circuit potential to prevent the re-oxidation of the Sn surface, and it continued until the -2 V vs. Ag/AgCl. This process was repeated similar to the previous set of experiments until the polarization curves did not change anymore. The results were consistent with the experiments that do not involve prior electroreduction. The polarization curves obtained in Ar saturated 0.1 M KHCO3 with pH 8.5 and H2SO4 added 0.1 M KOH with pH 6.8 were similar, but the reduction of the oxide was less in the H2SO4 added 0.1 M KOH. In the polarization curve obtained in CO2 saturated 0.1 M KHCO3 with 6.8 pH, no oxide peak has appeared. Thus, it can be suggested that the oxide is more prone to be reduced in the presence of CO2 or HCO3-. This experiment proves that the electrochemical CO2 reduction proceeds with not only CO2 gas but also HCO3- ions in the electrolyte. Additionally, at more cathodic potentials than -1.6 V vs. Ag/AgCl, it was clear that both hydrogen evolution reaction and electrochemical CO2 reduction reactions become kinetically limited because the slope of the curves become steeper. The steepness of the curves at more negative potentials than -1.6 V vs. Ag/AgCl can be listed as higher to lower, CO2 saturated 0.1 M KHCO3, Ar saturated 0.1 M KHCO3, and H2SO4 added 0.1 M KOH. Since, as the CO2 and HCO3- amount increases in the electrolyte the reaction becomes more limited, it can be said that the electrochemical CO2 reduction reaction becomes more limited than the hydrogen evolution reaction. In conclusion, the two main outcomes of this study is that the formate production rate was decreased with the reduction of the tin oxide, and total reduction of tin oxide on the surface is only achieved by the presence of CO2 in the solution indicating a synergic interaction between tin oxide and CO2. Thus, this study reveals the strong relationship between the tin oxide reduction reaction and ECR. In addition, it reveals the missing point in the literature about how tin oxide is affected by the electrochemical CO2 reduction reaction.
  • Öge
    Production Of Copper - silicon Carbide Composites For Thermal Management Applications By Electroforming Process
    (Institute of Science And Technology, 2019-06-11) Evren, Burak ; Ürgen, Mustafa Kamil ; 521171005 ; Malzeme Bilimi ve Mühendisliği ; Material Science and Engineering
    Technology of an era is limited with advancement in materials science. Validity of this phrase is much more sensible in todays world where science and technology are developing with acceleration. This statement is also perceptible in electronics. Size of the electronic elements is getting smaller every day in conjunction with an increment in number. Thus, components reach higher surface area values. As a result, released heat exceeds critical points and leads to deficiency in material performance and may even lead to material failure. For this reason, thermal management applications require a further attention. In this study, copper–silicon carbide composites are fabricated by electrochemical deposition method to serve as a thermal management material. Electrochemical deposition is conducted by using a modiefied version of Sediment-Codeposition (SCD) technique. A particular electrode system is designed for obtaining a self standing deposit. Acid copper sulfate electrolyte is selected as the electroforming bath.Silicon carbide particles are initially wetted in a solution containing the electroforming bath, afterwards they are manually settled on substrate surface of designed system. Different sets of experiments are conducted for achieving a smooth copper deposit between silicon carbide particles by 6 hours of electroforming. Operating conditions are benchmarked through obtaining cathodic polarization curve. The cathode potential corresponding to the optimized current density (1 A/dm2) is determined. Composite electroforming process is conducted potential controlled for keeping the current density stable because of continous area change of the cathode with the advancement of the coating process.After achieving the desired copper morphology for reinforcing silicon carbide particles, deposition time is extended to 30 hours. A set of samples are produced by using SiC particle with sizes of 75 µm and 1 mm. Scanning Electron Microscopy (SEM) investigations revealed that under these conditions it became possible to produce composite with 500 µm average thickness and over 65% reinforcing particle volume. At the matrix-particle interfaces some void formations but strong particle incorporation are observed.In order to enhance matrix-particle interface, as deposited samples are treated by annealing at 650 °C for 2 hours, cold isostatic pressing under 1500 kN for 10 minutes and cold isostatic pressing prior to annealing. SEM images of cold isostatic pressed samples reveal that copper is compressed from both surfaces and smooth copper morphology is converted to a needle-shaped, cornered form, while voids at the interfaces are diminished. For investigating the structural changes, x-ray diffraction patterns of samples are plotted. Copper peaks of as deposited sample shift to smaller angles, showing that compression stress forms during deposition. Annealing revokes compression stresses induced by deposition. Silicon carbide peaks are observed in diffraction pattern of cold isostatic pressed sample since copper gets compressed through harder silicon carbide particles, bringing these particles closer to composite surface. Wide peak broadening is seen for pressed samples as a result of induced compression strength and dislocations. Peaks are sharpened after annealing.X-ray diffraction patterns also show that silicon carbide particles do not chemically react with copper. Composite can be annealed at 650 °C without any significant structural change.Formability of the as deposited and annealed samples are measured by three point flexural test. Flexural strength of as deposited sample is 11.72 MPa while flexural strength of annealed sample is 4.67 MPa. Ductility is enhanced to composite by annealing.The viability of process for desired application is evaluated and concluded through experimental findings. Copper – silicon carbide composite is produced in the desired form and desired reinforcement concentration by electroforming. Depending on the usage area, the fabricated material is suitable for directly using as product right after deposition, or it can be cold isostatic pressed and annealed before operation.
  • Öge
    Effect Of Preparation Methods On Morphology And Rheological Properties Of PLA/CNC Nanocomposites
    (Institute of Science And Technology, 2020-06-12) Özdemir, Burcu ; Nofar, M Reza ; 521171006 ; Material Science and Engineering ; Malzeme Bilimi ve Mühendisliği
    Bio-based and biodegradable polymers are produced from biomass which is renewable by cultivation. The biopolymers degrade in natural environments decomposing into non-toxic substances. Moreover, during the cultivation process of raw material, biomass, of biopolymers CO2 is consumed and the amount of CO2 emission from the life cycle of biopolymers is much lower compared to that of petroleum-based polymers. Poly(lactic acid) or polylactide, PLA, is both Bio-based and biodegradable polyester-based polymer. It has comparable mechanical and physical properties with commonly used petroleum-based polymers. Thus, it is considered as a candidate to be replaced with widely used petroleum-based polymers. However, PLA has some drawbacks which limits is processability and applications. The shortcomings of PLA are slow crystallization kinetics and poor rheological properties. They result in slow crystallization rate, low thermal properties, low melt strength hence limited processability. Studies have shown that making nanocomposites of PLA by incorporation of nanoparticles into the PLA matrix could enhance its crystallization kinetics and viscoelastic properties. Cellulose nanocrystals (CNC) as being a biodegradable and Bio-based polymer has outstanding mechanical and thermal properties. Studies have shown that making PLA/CNC nanocomposites improve the thermal, crystallization, and rheological properties of PLA by preserving its biodegradable and Bio-based characteristics. However, the hydrophilic character of CNCs challenges its homogeneous dispersion in the hydrophobic PLA matrix which is crucial to improve PLAs properties, especially at low percolation concentrations. Studies have shown that without the use of any modification, the melt mixing process is not successful to disperse CNCs since the shear force applied during the process is not enough to break the strong hydrogen bonds between CNCs. Although it is not industrially feasible as melt mixing, it is possible to deagglomerate CNCs and to obtain good dispersion by solution casting method. The solution casting method involves the dispersion of CNC and PLA in proper solvents by using a water bath sonicator, tip sonicator, or magnetic stirrer followed by casting the mixture and followed by evaporation of the solvent. Studies have shown that the application of solution casting greatly differs in the instrument, the sequence of application, duration, PLA type, CNC type, and solvent type. This study aims to investigate the effect of preparation method, solvent, and CNC type on CNC dispersion thus the rheological and thermal properties of PLA/CNC nanocomposites. Low molecular weight and highly crystallizable PLA and two types of CNC were used to make nanocomposites. CNCs differ in their drying processes: spray-dried CNC (SCNC) in powder form and freeze-dried CNC (FCNC) in flake form. The rheological analysis was used as a characterization method to analyze the CNC dispersion. As the first step of the study, four different solvents were used to prepare nanocomposites of PLA/SCNC and PLA/FCNC at a fixed amount of CNC (3 wt.%). The solvents are tetrahydrofuran (THF), chloroform (CHL), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). The preparation method is followed as first dispersing CNC in the solvent using a bath sonicator for 2 hours at room temperature. Then PLA was added to the CNC solvent mixture and mixed with a magnetic stirrer for 2.5 hours (4 hours for DMSO). The temperature during magnetic stirring was selected according to the type of solvent. It was 55oC for THF and CHL since PLA is soluble in those solvents. PLA is not soluble in DMF and DMSO in room temperature thus, the temperature was increased above the glass transition temperature of PLA and it was 75oC for DMF and 95oC for DMSO (gradually increased). After the mixing process, the solvent containing PLA and CNC were casted into petri dishes and left to dry for 2 days under the fume hood followed by vacuum drying at 85oC for 2 days. After two days of vacuum drying, the films were ground with a coffee grinder and powders were further dried for 2 days under vacuum at 85oC. Nanocomposites prepared with DMSO revealed the highest improvement in rheological properties followed by DMF. THF resulted in a slight increase in total compared to neat PLA due to its much lower dielectric constant. However, nonpolar CHL couldn't deagglomerate CNC thus nanocomposites prepared with CHL revealed much lower viscoelastic properties than neat PLA. PLA/SCNC nanocomposites revealed slightly higher improvement in DMF and DMSO however, the difference was insignificant in THF and CHL. To investigate the effect of the preparation method, DMSO was chosen. Both PLA/SCNC and PLA/FCNC nanocomposites were prepared with varying water sonication times and sequences. In total four different methods were compared: 0WS-4MS, 2WS-4MS, 4WS-4MS, and 2WS-4MS-2WS. As an example, 2WS-4MS means 2 hours of water sonication followed by 4 hours of magnetic stirring. The highest improvement achieved with PLA/SCNC by the 4WS-4MS method. The increased water sonication time increased the dispersion of CNC however, the other methods displayed similar improvements. Moreover, since the CNC was in powder form only four hours of vigorous stirring at elevated temperature resulted in the second best improvement. It could be due to the DMSO's higher ability to disperse CNCs even without a bath sonicator. In the case of PLA/FCNC, 0WS-4MS revealed the highest improvement. Since the FCNC is in flake form the bath sonication at room temperature was not enough to disperse them. The method 2WS-4MS-2WS revealed the second-best result and better than the 2WS-4MS method. In the first method after 4 hours of magnetic stirring the PLA/FCNC and solvent mixture is placed in the bath sonicator when it was still hot. Thus, the high temperature of the solvent could aid the further dispersion of FCNC. To see the effect of CNC content (1, 2, 3, and 5 wt.%) it was decided to continue with SCNC since the results were more consistent. PLA/SCNC nanocomposites with DMSO by using 2WS-4MS method with varying CNC contents were prepared. To compare the results, nanocomposites with DMF was also prepared. PLA/SCNC nanocomposites with 5 wt.% revealed the highest improvement in rheological properties. In nanocomposites prepared with DMF, except PLA/SCNC1, nanocomposites revealed increased rheological properties. For the NCs prepared with DMSO, this increase was more pronounced. The rheological percolation threshold of NCs prepared with DMF and DMSO was calculated by employing the empirical power-law equation and found to be 1.59 and 0.44 wt.% respectively. The percolation concentration again revealed that DMSO is much more effective to obtain high quality dispersion of CNC. The apparent yield stress of NCs were calculated by employing Modified Herschel-Bulkley equation. NCs prepared with DMSO revealed much higher apparent yield stress values compared to ones prepared with DMF. Both the modified cole-cole plot analysis and Herschel-Bulkley plots of NCs revealed solid like behaviour started at percolation concentration. The isothermal DSC analysis of NCs revealed that due to better dispersion of CNC with DMSO, the NCs prepared with DMSO exhibit faster crystallisation kinetics. However, no significant change was observed between FCNC and SCNC. The neat PLA processes with DMSO revealed faster crystallisation compared to one with DMF. This could be due to higher plasticizing effect of DMSO since it is expected that higher amount of DMSO is remained in samples. Similarly, NCs prepared with different CNC content revealed that crystallisation time is close to that of neat PLAs. Those, results shows the effect of remaining solvent on NCs crystallisation.