Room Temperature Viscosity Research Articles

Synthesis, characterization and properties of vinyl-terminated poly[dimethylsiloxane-co-methyl(phenyl)siloxane]

Phenyl-containing polysiloxanes have better thermal stability, low-temperature flexibility, and room-temperature damping performance than polydimethylsiloxanes. Poly [dimethylsiloxane-co-methyl (phenyl)siloxane] and poly (dimethylsiloxane-co-diphenylsiloxane) were synthesized through a bulk copolymerization of octamethylcyclotetrasiloxane and methylphenylcyclosiloxane mixture or octaphenylcyclotetrasiloxane, and the structure and properties of the copolysiloxanes were comparatively studied. The phenyl content in poly [dimethylsiloxane-co-methyl (phenyl)siloxane] can be as high as 50 mol%. With the increment of the phenyl content, the thermal stability of the copolysiloxanes is dramatically improved as evaluated by thermal gravimetric analysis. At a given phenyl content, poly [dimethylsiloxane-co-methyl (phenyl)siloxane] has higher thermal stability than poly (dimethylsiloxane-co-diphenylsiloxane). The former is more difficult to crystalline at low temperatures and has lower room temperature viscosity than the latter as confirmed by differential scanning calorimetry and rotational rheometer. The copolysiloxanes is mixed with hydrogen-containing polysiloxane and silica, and vulcanized at elevated temperature to get copolysiloxane composites with good damping properties, oil resistance, and low-temperature resistance. This study not only enriches the fundamental academic research on functional polysiloxanes, but also provides useful technical references for practical applications of phenyl silicone rubber.

Investigation on Critical Characteristics of Edible Vegetable Oil by using Cuo Nanoparticles

This work demonstrates how the composition of the nanoparticles affects the thermal, electrical, and physical characteristics of vegetable oil (RBO). Cuo nanoparticles with particle volume fractions varying from 0.1 percent to 0.4 percent were injected one at a time into vegetable oil (RBO) to produce nanofluids (NFs) that affect the basic characteristics of the oil. It was able to evaluate characteristics including room temperature viscosity, firepoint, breakdown voltage (BDV), and flash point using IEC and ASTM standards. The breakdown voltage rises when the vegetable oil (RBO) oil is heated in the presence of nanoparticles. The size of the nanoparticles has changed the viscosity, and the flash and fire points have gone from 10°C to 15°C..

Synthesis, Characterization, and Magnetic Properties of Lanthanide-Containing Paramagnetic Ionic Liquids: An Evan's NMR Study.

The present study focuses on the synthesis and characterization of lanthanide-containing paramagnetic ionic liquids (ILs), [CnC1Im]3[MCl3X3] (n = 4, 6, and 8; M = Gd, Dy, and Ho; X = Br and Cl), derived from 1-alkyl-3-methylimidazolium anions. These paramagnetic ILs exhibit low vapor pressure, high thermal stability, physiochemical stability, and tunability, along with significant magnetic susceptibility, making them of interest in advanced material applications that may take advantage of neat liquids with magnetic susceptibility. Structural and physical properties were determined using FTIR, 1H NMR, DSC, and TGA. The room temperature density and viscosity of the iron paramagnetic ILs were also reported. Accompanying this report of paramagnetic IL products, we reintroduce and highlight Evan's NMR technique, an accessible magnetic susceptibility measurement technique that can utilize any available proton NMR to characterize the magnetic susceptibility of ILs. This work demonstrates the robustness of Evan's technique by demonstrating the ability to account for the IL water content, a common issue for hygroscopic materials, during the measurement of magnetic susceptibility. A detailed comparison of the ILs is presented, with dysprosium- and holmium-containing paramagnetic ILs exhibiting the highest magnetic susceptibility reported for mononuclear ILs reported to date. These materials have been studied with an eye on applications for mass transfer, eventually seeking to optimize magnetic susceptibility and viscosity using magnetic field gradients to move paramagnetic ILs carrying solute or heat. The study of paramagnetic ILs is important not only for understanding the magnetic properties of these materials but also for potential applications in areas such as magnetic resonance imaging, biomedicine, environmental remediation, and mass transfer. These unique materials have the potential to bring about new advances and technologies in the fields of materials science and analytical chemistry.

Comparative Study of Guanidine-, Acetamidine- and Urea-Based Chloroaluminate Electrolytes for an Aluminum Battery.

Aluminum-based batteries are a promising alternative to lithium-ion as they are considered to be low-cost and more friendly to the environment. In addition, aluminum is abundant and evenly distributed across the globe. Many studies and Al battery prototypes use imidazolium chloroaluminate electrolytes because of their good rheological and electrochemical performance. However, these electrolytes are very expensive, and so cost is a barrier to industrial scale-up. A urea-based electrolyte, AlCl3:Urea, has been proposed as an alternative, but its performance is relatively poor because of its high viscosity and low conductivity. This type of electrolyte has become known as an ionic liquid analogue (ILA). In this contribution, we proposed two Lewis base salt precursors, namely, guanidine hydrochloride and acetamidine hydrochloride, as alternatives to the urea-based ILA. We present the study of three ILAs, AlCl3:Guanidine, AlCl3:Acetamidine, and AlCl3:Urea, examining their rheology, electrochemistry, NMR spectra, and coin-cell performance. The room temperature viscosities of both AlCl3:Guanidine (52.9 cP) and AlCl3:Acetamidine (76.0 cP) were significantly lower than those of the urea-based liquid (240.9 cP), and their conductivities were correspondingly higher. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) showed that all three electrolytes exhibit reversible deposition/dissolution of Al, but LSV indicated that AlCl3:Guanidine and AlCl3:Acetamidine ILAs have superior anodic stability compared to the AlCl3:Urea electrolyte, as evidenced by anodic potential limits of +2.23 V for both AlCl3:Guanidine and AlCl3:Acetamidine and +2.12 V for AlCl3:Urea. Coin-cell tests showed that both AlCl3:Guanidine and AlCl3:Acetamidine ILA exhibit a higher Coulombic efficiency (98 and 97%, respectively) than the AlCl3:Urea electrolyte system, which has an efficiency of 88% after 100 cycles at 60 mA g-1. Overall, we show that AlCl3:Guanidine and AlCl3:Acetamidine have superior performance when compared to AlCl3:Urea, while maintaining low economic cost. We consider these to be valuable alternative materials for Al-based battery systems, especially for commercial production.

Formulation and Physical Stability Test of Essence Sheet Mask Preparation from Kokang Leaf Extract (Lapisanthes amoena)

Kokang leaf ethanol extract contains secondary metabolite compounds such as phenolics, flavonoids, tannins, steroids, and saponins that have antioxidant and antibacterial effects and play a role in wound healing. Seeing the potential in kokang leaves (Lepisanthes Amoena) until now the use of kokang leaves is still very lacking, therefore the need for innovation in the use of leaves, one of which is by developing a formulation of essence sheet mask preparations from kokang leaf extract (Lepisanthes Amoena). Formulations in the form of essence sheet masks are currently the latest developments in cosmetic preparations. The purpose of this study was to formulate and test the physical stability of the essence sheet mask preparation from the extract of kokang leaves. The preparation is made as many as 3 formulas, the leaf extract used is 0.1% (F1), 0.3% (F2), and 0.5% (F3). The evaluation carried out includes organoleptic tests (color, aroma, and texture), homogeneity tests, pH tests, room temperature stability tests, viscosity tests, and hedonic tests (favorability and irritation). The results showed that the preparation of the essence sheet mask was a thick solution with a characteristic green and homogeneous odor. The preparation of the essence sheet mask is stable at room temperature without any change. The pH value of the preparation essence sheet mask 5 – 6. Viscosity with a viscosity of 2,217 cP. A hedonic test of 12 panelists showed that the average favorability of all categories was superior to F2 (0.3%) and there was no irritation to the entire formula.

Exploration of hemocompatibility and intratumoral accumulation of paclitaxel after loco-regional administration of thermoresponsive hydrogel composed of poloxamer and xanthan gum: An application to dose-dense chemotherapy

Although paclitaxel is a front-line chemotherapeutic agent for the treatment of metastatic breast cancer, its intravenous therapy produces deleterious adverse effects. In an attempt to address the issue, the present study aimed to develop a paclitaxel loaded thermosensitive/thermoresponsive hydrogel (PTXNp-TGel) for loco-regional administration to breast tumors to provide dose-dense chemotherapy. Poloxamer and xanthan gum were used to prepare TGel by the cold method. In vitro and in vivo performance of PTXNp-TGel was compared with TGel, pure drug loaded TGel (PTX-TGel) and marketed formulation, Taxol®. The formulated PTXNp-TGel showed acceptable gelation temperature and time (37 °C and 57 s), lower viscosity at room temperature and higher viscosity at body temperature to support sol-gel transition with increasing temperature, and sustained drug release up to 21 days. Additionally, PTXNp-TGel showed negligible hemolytic toxicity as compared to PTX-TGel and Taxol®. Intratumoral administration of PTXNp-TGel produced significantly higher antitumor activity as indicated by lowest relative tumor volume (1.50) and relative antitumor proliferation rate (27.71 %) in comparison with PTX-TGel, Taxol®, and PTXNp (p < 0.05). Finally, insignificant body weight loss during the experimental period, lack of hematotoxicity, nephrotoxicity, and hepatotoxicity imply improved therapeutic performance of the locally administrated dose-dense therapy of PTXNp-TGel as compared to Taxol®.

Anthracene separation from analogous polycyclic aromatic hydrocarbons using the naphthalene-based solvents

Tricyclic aromatic hydrocarbons are difficult to be separated due to similar characteristics and boiling points, particularly anthracene and its isomer phenanthrene. The structural properties of anthracene and phenanthrene have been analyzed to identify the structural distinctions serving as critical factors to select a suitable solvent. Naphthalene-based solvents with electron-withdrawing substituent have been used to recognize phenanthrene molecules via electrostatic interaction. The separation performances of naphthalene-based solvents have been compared by the partition coefficient, purity, and yield, emphasizing the superior performance of acetylnaphthalene. The separation of anthracene is effective with a higher purity of 99.3 wt% and yield of 70.2 wt%, at room temperature and lower viscosity, economic cost savings of more than ten times, and beneficial by using the environment-benign back extractant. It also shows a better separation effect on real coal tar. In addition, the nonbonded interaction energy was further decomposed to illustrate the separation mechanism of naphthalene-based solvents from the energy perspective because the electrostatic interaction between phenanthrene and acetylnaphthalene plays a vital role. This work not only provides a new perspective on the selection of extractants but also promotes the application of intermolecular interaction in the separation and purification technology of analogous polycyclic aromatic hydrocarbons.

Enhanced and sustained transdermal delivery of primaquine from polymeric thermoresponsive hydrogels in combination with Dermarollers®

Primaquine (PMQ) is an effective antimalaria drug with several limitations. We report the combinatorial approach of thermoresponsive hydrogels and Dermarollers® for transdermal delivery of PMQ to overcome these limitations. The hydrogels were prepared using Pluronic F127 (PF127) and F68 (PF68). Specifically, HPMC was added into the formulation to improve the bioadhesive properties. Numerous formulations were prepared, showing that formulation comprising 15 % PF127, 3 % PF68 and 0.4 % HPMC with 1 % PMQ was selected as the optimum formulation. The formulation showed the gelation temperature around 35 °C with bioadhesive strength of 26.43 ± 2.31 dyne.cm2. Importantly, the pH of the formulation was suitable for skin application with the percentage of PMQ recovery of 99.57 ± 3.23 %. Moreover, the hydrogels exhibited free-flow liquid at storage and room temperature and high viscosities in the skin temperature. In vitro release experiments showed that the release of PMQ was sustained for 24 h. Evaluated in extensive ex vivo studies, the treatment with Dermarollers® improved the skin permeation and retention of PMQ for 3 days. In combination with Dermarollers®, the ex vivo permeation of PMQ was sustained and the localization of PMQ in the skin was improved over 72 h.

Global Distribution of the Phase State and Mixing Times within Secondary Organic Aerosol Particles in the Troposphere Based on Room-Temperature Viscosity Measurements

Information on the global distributions of secondary organic aerosol (SOA) phase state and mixing times within SOA is needed to predict the impact of SOA on air quality, climate, and atmospheric chemistry; nevertheless, such information is rare. In this study, we developed parameterizations for viscosity as a function of relative humidity (RH) and temperature based on room-temperature viscosity data for simulated pine tree SOA and toluene SOA. The viscosity parameterizations were then used together with tropospheric RH and temperature fields to predict the SOA phase state and mixing times of water and organic molecules within SOA in the troposphere for 200 nm particles. Based on our results, the glassy state can often occur, and the mixing times of water can often exceed 1 h within SOA at altitudes >6 km. Furthermore, the mixing times of organic molecules within SOA can often exceed 1 h throughout most of the free troposphere (i.e., ≳1 km in altitude). In most of the planetary boundary layer (i.e., ≲1 km in altitude), the glassy state is not important, and the mixing times of water and organic molecules are less than 1 h. Our results are qualitatively consistent with the results from Shiraiwa et al. (Nat. Commun., 2017), although there are quantitative differences. Additional studies are needed to better understand the reasons for these differences.

Optimized formulation of thermoresponsive nanoemulsion-based gel for enhanced oil recovery (EOR) application

A thermoresponsive system of a nanoemulsion-based gel with favorable characteristics to enhanced oil recovery (EOR) application is presented. A full factorial design study with different formulations of thermosensitive nanoemulsion-based gels was performed to assess the influence of the oil chain length, concentration of polyethylene glycol (PEG 400) and concentration of oil on the rheological behavior of the system. A formulation with low viscosity at room temperature and high viscosity at the temperature of the oil extraction well was presented. Hexane (6-carbon chain), capric acid (10-carbon chain) and isopropyl myristate (17-carbon chain) were used in concentrations of 5%, 10%, 15% and 20% wt%, also varying the concentration of PEG 400 in 0%, 3%, 6% and 9% wt%. The thermosensitive polymer used was a mixture of Pluronic® F-127 and Pluronic® F-68 6:1 wt% at 4.7% concentration. The surfactants used were Tween 80 and Span 80 (HLB = 13) at 20%. The formulation containing 20% isopropyl myristate (IPM) without the addition of PEG 400 showed a better response, with an increase in viscosity of more than 38 times in relation to its viscosity at 25 °C, and the maximum viscosity was reached at 53 °C. This is a promising formulation for EOR technology.

Ultrasonic shear wave reflectometry applied to the determination of the shear moduli and viscosity of a viscoelastic bitumen

Ultrasonic shear wave reflectometry is widely used in process control to measure the dynamic shear viscosities of Newtonian liquids. We apply the technique to study the temperature dependence of produced bitumen: a non-Newtonian ultra-heavy 6° API hydrocarbon with a room temperature viscosity of ∼103 Pa·s. The experimental apparatus employs a delay line made of polyetheretherketone (PEEK) whose shear impedance more closely matches that of the bitumen allowing for greater sensitivity but at the cost of long equilibration wait times. The temperature dependent values of the complex shear modulus and consequent estimates of the steady flow shear viscosity both follow close to an Arrhenius-like behaviour over the range of 10 °C–50 °C, but there are significant discrepancies between the ultrasonic and more conventional spindle viscosities. These may reflect differences between the particle displacements, the strains, and the strain rates associated with each measurement technique. It is in the nature of bitumen to shear thin at high shear rate using ultrasonic technique. Regardless, these measurements do show that the shear wave reflectometry does provide information on the changes in the viscoelastic bitumen with temperature that may be useful in for purposes of its monitoring during production and processing.

Sunlight Induced Rapid Oil Absorption and Passive Room‐Temperature Release: An Effective Solution toward Heavy Oil Spill Cleanup

AbstractRapid cleanup and easy recovery of spilled heavy oils is always a great challenge due to their high viscosity (&gt;103 mPa s). One of the efficient methods to absorb highly viscous oils is to reduce their viscosity by increasing their temperature. In this work, the authors integrate the sunlight‐induced light‐to‐heat conversion effect of polypyrrole (PPy) and thermoresponsive property of poly(N‐isopropylacrylamide) (PNIPAm) into the melamine sponge, which successfully delivers a fast heavy oil absorption under sunlight and passive oil release underwater at room temperature. Thanks to the rationally designed functionalities, the PNIPAm/PPy functionalized sponges possess oleophilicity and hydrophobicity under sunlight. Due to the photothermal effect of PPy, the sponges locally heat up contacting heavy oil under sunlight and reduce its viscosity to a point where the oil voluntarily flow into the pores of the sponge. The material in this work is able to rapidly absorb the heavy oil with room temperature viscosity as high as ≈1.60 × 105 mPa s. The absorbed oil can be passively forced out the sponge underwater at room temperature due to the hydrophilicity of PNIPAm. The sunlight responsive and multifunctional sponge represents a meaningful attempt in coming up with a sustainable solution toward heavy oil spill.

Mixing times of organic molecules within secondary organic aerosol particles: a global planetary boundary layer perspective

Abstract. When simulating the formation and life cycle of secondary organic aerosol (SOA) with chemical transport models, it is often assumed that organic molecules are well mixed within SOA particles on the timescale of 1 h. While this assumption has been debated vigorously in the literature, the issue remains unresolved in part due to a lack of information on the mixing times within SOA particles as a function of both temperature and relative humidity. Using laboratory data, meteorological fields, and a chemical transport model, we estimated how often mixing times are &lt; 1 h within SOA in the planetary boundary layer (PBL), the region of the atmosphere where SOA concentrations are on average the highest. First, a parameterization for viscosity as a function of temperature and RH was developed for α-pinene SOA using room-temperature and low-temperature viscosity data for α-pinene SOA generated in the laboratory using mass concentrations of ∼ 1000 µg m−3. Based on this parameterization, the mixing times within α-pinene SOA are &lt; 1 h for 98.5 % and 99.9 % of the occurrences in the PBL during January and July, respectively, when concentrations are significant (total organic aerosol concentrations are &gt; 0.5 µg m−3 at the surface). Next, as a starting point to quantify how often mixing times of organic molecules are &lt; 1 h within α-pinene SOA generated using low, atmospherically relevant mass concentrations, we developed a temperature-independent parameterization for viscosity using the room-temperature viscosity data for α-pinene SOA generated in the laboratory using a mass concentration of ∼ 70 µg m−3. Based on this temperature-independent parameterization, mixing times within α-pinene SOA are &lt; 1 h for 27 and 19.5 % of the occurrences in the PBL during January and July, respectively, when concentrations are significant. However, associated with these conclusions are several caveats, and due to these caveats we are unable to make strong conclusions about how often mixing times of organic molecules are &lt; 1 h within α-pinene SOA generated using low, atmospherically relevant mass concentrations. Finally, a parameterization for viscosity of anthropogenic SOA as a function of temperature and RH was developed using sucrose–water data. Based on this parameterization, and assuming sucrose is a good proxy for anthropogenic SOA, 70 and 83 % of the mixing times within anthropogenic SOA in the PBL are &lt; 1 h for January and July, respectively, when concentrations are significant. These percentages are likely lower limits due to the assumptions used to calculate mixing times.

Study on off-state characteristics of polyurethane based magnetorheological gels

Magnetorheological gel(MRG) has variable off-state viscosity and it’s anti settling performance is very good. Four different ratios of polyurethane based MRGs were prepared (The mass fraction of iron particles was 10%, 25%, 50%, 75%, respectively), and at room temperature (25 ℃) flow characteristics and viscosity characteristics of off-state of samples was tested. The results indicated that both in the rising and falling stages there is a linear relationship between shear rate and shear stress except shear rate above 110 s-1 of MRG-75. The shear stress increases with the increase of particle content. All samples shown obvious shear thinning characteristics, and the viscosity increases with the increase of particle content.

Viscous flow of medieval cathedral glass

AbstractA popular urban legend concerns the apparent flow of stained glass windows in medieval cathedrals, where the glass windows are commonly observed to be thicker at the bottom than they are at the top. Advances in glass transition theory and experimental characterization techniques now allow for us to address this urban legend directly. In this work, we investigate the dynamics of a typical medieval glass composition used in Westminster Abbey. Depending on the thermal history of the glass, the room temperature viscosity is on the order of 1024 to 1025 Pa·s, about 16 orders of magnitude lower than found in a previous study of soda lime silicate glass. This measurement is in quantitative agreement with a newly derived model for the composition dependence of the nonequilibrium viscosity of glass. Despite this significantly lower value of the room temperature viscosity, the viscosity of the glass is much too high to observe measurable viscous flow on a human time scale. Using analytical expressions to describe the glass flow over a wall, we calculate a maximum flow of ~1 nm over a billion years.

Fluid-like Surface Layer and Its Flow Characteristics in Glassy Nanotubes.

We show that amorphous silica and Si nanotubes can flow at room temperature under Giga-Pascal order stress when going to the nanometer scale. This creep behavior is unique for the amorphous nanotubes and is absent in crystalline Si nanotubes of similar dimensions. A core-shell model shows that there exists an approximately 1 nm thick viscoelastic "fluid-like" surface layer, which exhibits a room temperature viscosity equivalent to that of bulk glass above 1000 °C.

Study of the Curing Kinetics toward Development of Fast-Curing Epoxy Resins

ABSTRACTRapid resin transfer molding is suitable for high-volume production of composite products. In this work, the epoxy systems with long pot life, i.e., with low reactivity at room temperature and low viscosity for fast injection into the mold cavity and reinforcing fabric, were developed by varying different concentrations of diluent and catalyst. Once infusion is completed, such epoxy formulations were capable of reacting fast at cure temperatures. Different formulations were developed to achieve such goals. This paper reports on the investigation of cure rate, cure temperature, cure time, glass transition temperature, and in situ cure monitoring using differential scanning calorimetry.

Multifunctional liquid-like graphene@fe3o4hybrid nanofluid and its epoxy nanocomposites

Novel multifunctional graphene@Fe3O4 hybrid nanofluid with liquid-like behavior at room temperature and low viscosity (5.5 Pa.s at 25°C) has been developed by using GO@Fe3O4 as a core, sulfuric acid-terminated organosilanes as corona, and polyether amine as canopy. The obtained nanofluid has been extensively characterized by various analytical techniques. The content of graphene@Fe3O4 reaches up to 13.78 wt% in the hybrid nanofluid, which is a superparamagnetism material with specific magnetization of 0.39 emu/g. In addition, it shows excellent dispersion and exfoliation in solvents and polymer matrixes. It is then compounded with an epoxy resin for the development of liquid-like graphene@Fe3O4 hybrid nanofluid/epoxy nanocomposites. It is found that liquid-like graphene@Fe3O4 hybrid nanofluid/epoxy nanocomposites demonstrate better mechanical property than those of unmodified graphite/epoxy nanocomposites at the same fraction. For example, the multifunctional liquid-like graphene@Fe3O4 hybrid nanofluid at 1.5 wt% improves the impact toughness of epoxy by 125%. This new interface modification also enhanced the Tg of neat epoxy from 98.37 to 129.46°C. POLYM. COMPOS., 2015. © 2015 The Authors Polymer Composites published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers

Li-doped mixtures of alkoxy-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)-imide and organic carbonates as safe liquid electrolytes for lithium batteries

The availability of safer electrolytes is an important target in the development of the new lithium batteries. The use of Li-doped mixtures based on ionic liquids and organic carbonates seems to be a very promising approach, because it allows to balance the non-flammability, high conductivity, low viscosity and good electrochemical stability.Here, we reported on the characterization of electrolytes solutions based on N-methoxyethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)-imide (PYR1,2O1TFSI), EC/DEC binary system and LiTFSI, as potential safe electrolytes for lithium batteries. The mixtures were studied in terms of flammability tests, thermal features, physical properties, namely conductivity and viscosity, and electrochemical performances. We also carried out a comparison with the pure IL–Li salt system as well as with the standard electrolyte 1.0 M LiPF6 EC–DEC.The best solution showed ionic conductivity exceeding 7 mS cm−1 at 20 °C, room temperature viscosity lower of about 25 cPs and an overall electrochemical window of 4.5 V. With respect to the pure LiTFSI–IL electrolyte, a very stable interface with Li anode was also observed in at least for 20 storage days. This mixture was tested in a LiFePO4-based cell, and showed good performances at 1 C, assuring electrochemical stability for about 250 cycles with ∼100% efficiency.

Thermal and rheological behavior of acetylacetone stabilized ZnO nanofluids

Acetylacetone (acac) ligand has been used for stabilization of ZnO NPs in water that form weak chelating complex which simultaneously breaks ZnO clusters, wrap and make ZnO NPs water soluble. Both thermal effusivity and conductivity show sigmoidal behavior over a temperature range of 283–323 K for low concentration fluids. The flow characteristics show rheopectic behavior according to concentration of ZnO NPs with highly non-Newtonian characteristics at lower shear stresses. Temperature dependence of the rheological characteristics suggests that above room temperature viscosity is higher for higher concentration nanofluid that can be attributed to agglomeration.