Dispersion Quality Research Articles

Punica granatum: A plant with a high potential for the synthesis of silver nanoparticles

O Objective: To use pomegranate (Punica granatum L.) extracts as a reducing agent for a simple and eco-friendly biosynthesis of silver nanoparticles and to test the latter’s antimicrobial potential against different bacteria. Methodology: The leaves and peel of ripe fruits of pomegranate were used to prepare aqueous and methanolic extracts to synthesize silver nanoparticles (AgNP). Then we evaluated these nanoparticles with techniques that allowed us to define their size, shape, and dispersion quality in aqueous media. To characterize the AgNPs we resorted to UV-Vis spectroscopy and dynamic light scattering (DLS). We determined their antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, and Staphylococcus aureus. Results: UV-Vis spectra were observed with absorption peaks at 425 nm for the nanoparticles synthesized with both aqueous and methanolic extracts. Regarding size, distribution, and dispersion in solution, the zeta potential shows that the surface charge in all cases is negative, with an average value ranging from -28.0 mV to -52.0 mV. Smaller nanoparticles were obtained from the aqueous extracts of the peel and leaves, with values between 1.42 - 2.96 nm, while the methanolic extracts yielded nanoparticles of 10 - 19.04 nm. Inhibition of microorganisms proved to be best against Escherichia coli, with a minimum inhibitory concentration (MIC) of 0.83 µg/mL up to 6.68 µg/mL. Conclusions: This study suggests that pomegranate extracts synthesize small-sized, well-dispersed silver nanoparticles with an almost spherical morphology, and good antimicrobial activity against gram-negative bacteria such as Escherichia coli.

Shear Wave Dispersion in Chronic Liver Disease: From Physical Principles to Clinical Usefulness.

The development of new applications in ultrasound (US) imaging in recent years has strengthened the role of this imaging technique in the management of different pathologies, particularly in the setting of liver disease. Improved B-mode imaging (3D and 4D), contrast-enhanced US (CEUS) and especially US-based elastography techniques have created the concept of multiparametric ultrasound (MP-US), a term borrowed from radiological sectional imaging. Among the new elastography techniques, shear wave dispersion is a newly developed imaging technology which enables the assessment of the shear waves' dispersion slope. The analysis of the dispersion qualities of shear waves might be indirectly related to the tissue viscosity, thus providing biomechanical information concerning the pathologic state of the liver such as necroinflammation. Some of the most recent US devices have been embedded with software that evaluate the dispersion of shear waves/liver viscosity. In this review, the feasibility and the clinical applications of liver viscosity are reviewed based on the preliminary findings of both animal and human studies.

Friedel-Crafts Reaction of Vinyltrimethoxysilane with Styrene and Composite Materials on Their Base

Friedel-Crafts alkylation reaction of vinyltri-methoxysilane with styrene was performed in the pres-ence of anhydrous AlCl3. Alkoxy(4-vinylphenethyl)silane has been obtained. The synthesized products were identified by 1H, 13C, COSY NMR, and FTIR spectroscopy. Calculations using the quantum-chemical non-empirical density functional theory (DFT) method for the reaction between vinyltrimethoxysilane and styrene performed for ortho-, meta- and para-positions were discussed. For the theoretical modeling an online prediction program "Priroda 04: A quantum-chemical program suite" was used. Composite materials based on wood sawdust with various dispersion qualities and synthesized trimethoxysilylated styrene as a binding and reinforcing agent with degrees of silylation (5 %), in the presence of various organic/inorganic additives, fire retardants, and antioxidants, have been developed at different temperatures and pressures via hot press method or extrusion. The physico-mechanical properties of composites have been investigated.

Ultrasonic Velocity, Viscosity and Thermal Conductivity Studies on Barium Oxide: Silicone Oil Nanofluids

In this study, we focused on the preparation and characterization of Barium oxide (BaO): Silicone oil nanofluids with the assistance of ultrasonication. The purpose was to investigate the potential impact of these nanofluids on solar radiation absorption. To achieve this, six different concentrations (ranging from 0.01 g to 0.06 g) of BaO: Silicone oil nanofluids were prepared. The nanofluids were subjected to various characterization techniques to evaluate their properties. Ultrasonic velocity measurements were conducted to assess the dispersion quality and stability of the nanofluids. Fourier transform infrared (FTIR) spectroscopy was utilized to examine any potential interactions between the nanoparticles and the fluid medium. Ultraviolet-Visible (UV-Visible) spectroscopy was employed to investigate the optical properties of the nanofluids, particularly their ability to absorb solar radiation. Additionally, electron microscopy analysis provided insights into the morphology and size distribution of the BaO nanoparticles. The results obtained from the UV-Visible analysis provided valuable information regarding the solar radiation absorption efficiency of the BaO: Silicone oil nanofluid systems. These findings contribute to our understanding of the potential application of these nanofluids in solar energy harvesting. Furthermore, the ultrasonic studies and FTIR analysis confirmed that there were no significant particle-fluid interactions, indicating the stability of the nanofluids. Thermal conductivity measurements were carried out to determine the heat transfer efficiency of the BaO: Silicone oil nanofluid system at different concentrations. The results revealed an optimal concentration that exhibited the highest heat transfer efficiency, suggesting the potential of these nanofluids for enhancing heat transfer processes. In conclusion, this study successfully prepared and characterized BaO: Silicone oil nanofluids. The analysis of their optical properties, stability, and thermal conductivity provides valuable insights into their potential application in solar radiation absorption and heat transfer systems. Further research can explore the practical implementation of these nanofluids in solar energy conversion and thermal management technologies.

Optimizing the dispersion of calcium phosphate nanoparticles for cellular studies using statistical design of experiments

The in vitro experimentation of ceramic nanoparticles often requires their dispersion in liquid media without causing particle clumps or deteriorating sample integrity. However, the dispersion of nanoparticles using the available protocols rarely leads to stable and uniform dispersions which, in turn, raises concerns about the validity, repeatability and comparability of the findings observed in vitro. Moreover, the ability to control the final dispersion quality of ceramic nanoparticles is an essential step to obtaining optimized nanoceramic materials with desired functionality and to enhancing their performance in subsequent applications. While the need to have a comprehensive guideline for the dispersion of nanoparticles has led to several published documents and protocols, the dispersion methodology of ceramic nanoparticles and the relative contribution of the experimental parameters to the quality of resulting dispersion are still not clear. Here, we employed the statistical design of experiment (DoE) approach to systematically assess the magnitude and source of variation in dispersion quality of two different ceramic nanoparticles, hydroxyapatite and tricalcium phosphate. Using the first-order Plackett-Burman Design (PBD), nanoparticle concentration, pH and the presence of an additive were identified as the most critical factors influencing the resulting hydrodynamic size and zeta potential of the ceramic nanoparticles. Optimization using a second-order Central Composite Design (CCD) yielded a set of quadratic regression equations that were used to predict the hydrodynamic size or zeta potential of ceramic nanoparticles with high accuracy (R2, 0.88–0.92). The results of PBD screening and CCD optimization experiments were employed to prepare nanoparticle dispersions of different quality, which were then used to compare the effect of aggregation on the viability of human osteosarcoma (SaOS-2) cells. Overall, the results of this study provided insight into the role that various experimental parameters play in the colloidal stability and dispersion of ceramic nanoparticles.

Green Bionanocomposites Based on Polyhydroxybutyrate and Filled with Cellulose Nanocrystals: Melting Processing and Characterization

This article contributes to the understanding of biobased and biodegradable polyhydroxybutyrate (PHB) bionanocomposites melt processed by pre-industrial methods such as extrusion and injection molding and reinforced by weight contents of 1 and 3 wt% of cellulose nanocrystals (CNC) derived from waste streams of the paper industry. Ultrasonic treatment was used for dispersion of the CNC, which was followed by transmission electron microscopy. The thermal properties and the crystallization behavior of bionanocomposites were studied by thermogravimetric analysis, differential scanning analysis, X-ray diffraction and polarized optical microscopy. Investigations on the bending properties were carried out in conjunction with the analysis of their dynamic mechanical behavior. Scanning electron microscopy was used to characterize the fracture surface. All these analyses give a deep insight into their structure-property relationship. The moisture absorption measurements and gas barrier properties analysis made to the processed bionanocomposites have provided an insight into their behavior under environmental conditions. The PHB bionanocomposites with a low content of 1 wt% CNC were found to have the best dispersion quality, which had a positive effect on almost all mechanical and thermal properties. The increase in crystallinity with the incorporation of CNC also contributed to an improvement in mechanical properties. In addition, the bionanocomposites show a slightly lower tendency to absorb moisture and better barrier properties to oxygen and water vapor. These findings showed that these bionanocomposites are suitable for use in the packaging industry.Graphical

MODELING AND OPTIMIZATION OF PROCESS PARAMETERS OF THE PISTON ALLOY-BASED COMPOSITE PRODUCED BY FSP USING RESPONSE SURFACE METHODOLOGY

In this paper, A356/B4C composites were fabricated using the friction stir processing (FSP) method. The process’s input parameters, including rotational and transverse speed, were optimized using the response surface methodology (RSM). Three factors and three levels with nine experimental runs made up the design of the experiments. An analysis of variance (ANOVA) was employed to determine whether the constructed model was adequate at a 95% confidence level. This study found that transverse speed was the most critical variable affecting the composites’ silicon (Si) particle size, UTS, and force. The findings demonstrate that the Si particle size of the parent material and the dispersion quality of B4C particles in the aluminum matrix are considerably influenced by the FSP factors, such as rotating speed and transverse speed. Second, tests for tensile strength were conducted to examine the composites’ mechanical properties. Then, using a specially designed fixture to measure force during the process, the forces on the tool, which play a decisive role in determining the tool’s life, were measured in different input parameters. The findings demonstrate that FSP transforms the mechanism of the fracture from brittle to extremely ductile in composites from the as-received metal.

Hybrid effect of GNPs, GOs, and CNTs on the flexural and compressive strengths of cement paste

This paper presents the individual and synergic effects of Graphene Nanoplatelets (GNPs), Graphene Oxides (GOs) and Carbon Nanotubes (CNTs) on the flexural and compressive strengths of cement paste. Mixes containing several nanoparticle types and weight fractions were prepared with Polycarboxylate ether (PCE) surfactant and tested after 90 days of curing. After that, the microstructure of the failed samples was studied using a Scanning Electron Microscope (SEM). Response Surface Methodologies (RSM) techniques were then employed to determine the strength functions' response to the nanofilaments' types and weight fractions. Finally, a cost analysis was done to evaluate the mixes' performance in-terms of strength and cost. Test results showed that the flexural strength of cement paste could be enhanced by 57.33% when using 0.04 wt % GOs. The results also showed that mixes containing 0.08 wt % GOs and 0.12 wt % CNTs improved the flexural strength by 47.03 and 44.38%, respectively when compared with the control cement paste mix. In-terms of compressive strength, mixes containing 0.04 wt % GNPs attained the highest compressive strength improvement of 15.7% when compared with the control mix. In hybrid mixes containing more than one nanoparticle type, the best synergistic action was generated between 50% CNTs and 50% GOs at a total dosage of 0.04% wt, where the compressive strength increased by 20.2%. The microstructural analysis showed good dispersion qualities and nanoparticles embedment within cement hydration products. On the other hand, RSM analysis showed that the maximum compressive and flexural strength functions' responses are obtained at the lowest nanofilaments’ weight fraction of 0.04 wt %. The desirability analysis confirmed that the compressive and flexural strengths of cement paste could be improved by 7 and 53%, respectively, using the predicted formulas. Finally, the cost analysis showed that GO-modified cement pastes are considerably more expensive than other mixes, yielding the lowest economic index.

Effect of the carboxyl group number of the complexing agent on polishing performance of alumina slurry in sapphire CMP

Alumina abrasive has a high polishing rate in the polishing process, but there are issues that need to be addressed with poor dispersion and poor post-polishing surface quality. This study used complexing agents with various numbers of carboxyl groups to prepare a series of alumina slurries. Scanning electron microscope images and zeta potential analysis demonstrated that the complexing agents could effectively increase the absolute value of alumina particles’ zeta potential and significantly enhance their dispersibility. Additionally, utilizing the UNIPOL-1502 polishing machine, the chemical mechanical polishing (CMP) performance of polishing slurries with complexing agents on sapphire substrates was investigated. According to the findings, as the carboxyl group count rises, material removal initially increases and subsequently declines. The material removal rate using alumina slurry added with complexing agent disodium ethylenediaminetetraacetic acid (the number of carboxyl groups is 4) can reach up to about 4.0 μm/h, which is 52% higher than that without complexing agents, while the average surface roughness of 0.96 nm can be obtained, which is 51% less than that without complexing agents. The X-ray photoelectron spectroscopy results showed that the complexing agents can react with the abrasive particles and sapphire substrates. The friction coefficient test and contact angle test revealed that slurries with complexing agents demonstrated excellent wettability and mechanical action. The sapphire surface becomes smoother as a result of the synergistic effect of chemical etching and mechanical removal.

Bioactive trans-resveratrol as dispersant of graphene in water. Molecular interactions

Currently, the preparation of high-quality graphene (G) dispersions is crucial due to the increasing demand for this nanomaterial in a wide range of industries. However, given the strong π–π stacking tendency between G sheets, dispersant agents such as surfactants or polymers are required to attain stable and homogenous dispersions in liquid media. In the present work, the effectiveness of resveratrol (RV), a fluorescent bioactive compound with antioxidant activity, as a dispersing agent for G in aqueous solutions was assessed. The interaction between G and RV was investigated via absorbance, fluorescence and Raman measurements. Dispersions were prepared via bath sonication, followed by probe ultrasonication and centrifugation, though the two last stages have little effect on the dispersion quality. The addition of G causes a quenching on RV fluorescence, and its magnitude raises with increasing G concentration, being the effect stronger up to 10 mg L-1. The change in the centrifugation speed and time have hardly influence on the RV fluorescence in the presence of G. The RV content remaining in the bulk solution after G dispersion, measured via UV–Vis absorption, decreases linearly with increasing G concentration. RV can effectively disperse all the G present in the sample up to 10 mg L-1; at higher concentrations, the dispersing ability slightly decreases, and the G content is distributed between the bulk solution and the centrifuged residue. Besides, the fluorescence of RV dispersed in G is much higher in methanol than in an aqueous medium. TEM analysis confirms the good exfoliation of G upon ultrasonication in RV solutions and indicates that the layer thickness depends on the G/RV ratio. The results of this study could open new perspectives for using natural products like resveratrolas biocompatible and efficient dispersing agents of G to be used in numerous applications, especially in biomedicine.

Sonochemical Synthesis of CuO Nanoplatelets and Their Tribological Properties as an Additive in Synthetic Oil Using Reciprocating Tribometer

This Research aimed to improve the tribological properties of commercially available lubricating oil (5W-40) by incorporating CuO nanoplatelets (NPs) synthesized using a simple and cost-effective sonochemical method. To evaluate the performance of the nanolubricant, a reciprocating tribometer was indigenously designed and developed to measure the coefficient of friction (COF) and wear tracks between two AISI 1045 steel surfaces. The CuO NPs were characterized using XRD to confirm their purity and phase, while SEM and FE-TEM were utilized to study their morphology and composition. Raman spectroscopy was used to reveal three distinct Raman active peaks of CuO at 283, 330, and 616 cm−1. Zeta potential measurements demonstrated good dispersion quality, with a value of 92.0 mV for 0.1% concentration. SEM and FE-TEM analysis of the nanolubricant showed the formation of a tribo-film over the CuO NPs and adding 0.1% CuO NPs reduced COF by 32%. These findings suggest that incorporating synthesized CuO NPs in commercially available lubricating oil can enhance its tribological properties, leading to improved machine efficiency and lifespan, as well as reduced energy demand. Overall, the study demonstrates the potential benefits of using CuO nanoplatelets as an additive in lubricating oil, which could have significant implications for the development of more efficient nanolubricants.

Effects of Silica/Clay Nanoparticles on Microstructural and Mechanical Properties of Epoxy Based Adhesives

Improving the mechanical properties of the epoxy-based adhesives with nanoparticles is one of the methods which justifies the use of adhesive joints significantly. This work studies the strength of adhesively bonded single-lap joints (SLJs) considering the pure adhesive, the reinforced adhesive with nano-silica particles (NSPs), nano-clay particles (NCPs), and a combination of both nano particles. Uniaxial tensile testing of the SLJs was conducted to reveal the failure loads of the joints and their elongations at failure. Furthermore, Scanning electron microscope (SEM) images and X-ray Diffraction (XRD) Analyses were used to investigate dispersion quality. It was observed that the use of just 1 wt.% NCPs or 2 wt.% NSPs improve the failure load significantly whereas the combination of both particles generally leads to large agglomerations. It is also concluded that the dispersion quality is a key to improve the strength by shifting the failure mechanism from adhesion to cohesion type.

Fruit secondary metabolites alter the quantity and quality of a seed dispersal mutualism.

Plant secondary metabolites are key mechanistic drivers of species interactions. These metabolites have primarily been studied for their role in defense, but they can also have important consequences for mutualisms, including seed dispersal. Although the primary function of fleshy fruits is to attract seed-dispersing animals, fruits often contain complex mixtures of toxic or deterrent secondary metabolites that can reduce the quantity or quality of seed dispersal mutualisms. Furthermore, because seeds are often dispersed across multiple stages by several dispersers, the net consequences of fruit secondary metabolites for the effectiveness of seed dispersal and ultimately plant fitness are poorly understood. Here, we tested the effects of amides, nitrogen-based defensive compounds common in fruits of the neotropical plant genus Piper (Piperaceae), on seed dispersal effectiveness (SDE) by ants, which are common secondary seed dispersers. We experimentally added amide extracts to Piper fruits both in the field and lab, finding that amides reduced the quantity of secondary seed dispersal by reducing ant recruitment (87%) and fruit removal rates (58% and 66% in the field and lab, respectively). Moreover, amides not only reduced dispersal quantity but also altered seed dispersal quality by shifting the community composition of recruiting ants (notably by reducing the recruitment of the most effective disperser by 90% but having no detectable effect on the recruitment of a cheater species that removes fruit pulp without dispersing seeds). Although amides did not affect the distance ants initially carried seeds, they altered the quality of seed dispersal by reducing the likelihood of ants cleaning seeds (67%) and increasing their likelihood of ants redispersing seeds outside of the nest (200%). Overall, these results demonstrate that secondary metabolites can alter the effectiveness of plant mutualisms, by both reducing mutualism quantity and altering mutualism quality through multiple mechanisms. These findings present a critical step in understanding the factors mediating the outcomes of seed dispersal and, more broadly, demonstrate the importance of considering how defensive secondary metabolites influence the outcomes of mutualisms surrounding plants.

Evaluating Mixing Height Estimations in the Western United States Using Satellite Observations

Wildfire smoke can be transported far from its origin, adversely impacting human health. The height of the atmospheric mixing layer, the near-surface layer of the troposphere in which turbulent convection leads to vertical mixing, is called the mixing height. Mixing height is a critical input in the smoke dispersion and air quality models used by agencies that monitor wildfires and air pollution. These models, coupled with forecaster expertise, are also used to determine if it is safe to execute a prescribed burn. In this paper, we derive mixing heights from two satellite datasets in order to assess mixing height forecasts produced by the National Weather Service (NWS) Fire Weather Program. Namely, we use Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) Vertical Feature Masks (VFM) and vertical water vapor profiles from the Moderate Resolution Imaging Spectroradiometer (MODIS). Our comparison indicates that NWS forecasts tend to underestimate CALIOP mixing heights with a median relative error of –13% and a mean relative error of –3.34%. Although MODIS and NWS mixing heights showed some agreement below 3 km, the lower vertical resolution of the MODIS estimates hindered a full comparison. We examine the discrepancies among mixing heights over wildfire smoke plumes determined by these methods and discuss biases and limitations. This work provides insight into potential bias patterns present in current mixing height forecasts and provides directions for future improvements in both NWS mixing height forecasts and satellite-based measurements of mixing height.

The Movement Ecology of Mutualism (CSEE/ESA 2022, OOS17)

The Movement Ecology of Mutualism (<scp>CSEE</scp>/<scp>ESA</scp> 2022, <scp>OOS17</scp>)

The Effect of Silica Particle Size on the Mechanical Enhancement of Polymer Nanocomposites

In the present work, SiO2micro/nanocomposites based on poly-lactic acid (PLA) and an epoxy resin were prepared and experimentally studied. The silica particles were of varying sizes from the nano to micro scale at the same loading. The mechanical and thermomechanical performance, in terms of dynamic mechanical analysis, of the composites prepared was studied in combination with scanning electron microscopy (SEM). Finite element analysis (FEA) has been performed to analyze the Young's modulus of the composites. A comparison with the results of a well-known analytical model, taking into account the filler's size and the presence of interphase, was also performed. The general trend is that the reinforcement is higher for the nanosized particles, but it is important to conduct supplementary studies on the combined effect of the matrix type, the size of the nanoparticles, and the dispersion quality. A significant mechanical enhancement was obtained, particularly in the Resin/based nanocomposites.

QUANTIFYING SULFUR DISPERSION USING POPULATION SURVIVAL ANALYSIS OF TENSILE STRENGTH

ABSTRACT High-performance rubber compounds require good dispersion of polymers, fillers, and other additives. However, fine powdery additives such as zinc oxide and insoluble sulfur (IS) are characteristically difficult to disperse, and poor dispersion may lead to large crosslink and modulus gradients in the final vulcanizate. IS dispersion can be assessed directly or indirectly, yet many techniques suffer from a lack of sensitivity and accuracy or are cost prohibitive. Herein, we describe the application of a two-parameter Weibull distribution and population survival analysis of cured rubber tensile strength as a simple technique to evaluate IS dispersion. We use statistical tools to determine the optimum number of sample replicates required to differentiate the quality of dispersion in rubber articles through the Weibull scale and shape estimates (α and β, respectively). We then demonstrate how mixing cycle time and intensity affect the dispersion of two IS grades and show that judicious choice of IS can lead to reduced cycle mix times, productivity improvements, and energy cost savings.

Influence of different dispersants on the quality and stability of aqueous quinacridone magenta pigment dispersion for ink‐jet applications

AbstractThe stability of water‐based pigment dispersions is a key factor in determining their utility in ink‐jet applications, and the appropriate choice of dispersant plays a special role. Among the pigment formulations tested to date, literature data on magenta pigments are very limited. Thus, the goal of this work was to study the influence of the type and loading of dispersants on the quality and stability of quinacridone magenta pigment dispersions. Three different commercially available dispersants were tested: (1) a cationic styrene‐maleic anhydride copolymer, (2) an anionic polyacrylate, and (3) a nonionic alkyl ethoxylate. Pigment and dispersing agents were analysed using the Fourier Transform–infrared method. The stability of pigment dispersions was determined by comparative studies of changes in the pigment particle size, viscosity, pH, filtration time, optical density and gloss during the accelerated ageing test. Moreover, Turbiscan AGS and LUMiFuge analysers were used for evaluations of the instability of the dispersions. The properties of each dispersing agent affected the performances of the different dispersants. The highest stability for the pigment formulations was provided using the nonionic dispersant (small particle size, &lt; 60 nm; the lowest viscosity &lt; 60 mPa·s at the optimal dispersant content; favourable results of the filtration test; the highest pigment dispersability, proven by optical density and gloss). The Turbiscan AGS and LUMiFuge results indicated that the stability of all tested quinacridone magenta pigment dispersions was excellent (Turbiscan Stability Index values below three, and no significant differences in transmission profiles, respectively). However, it was found that the measurement results were influenced by the viscosity of the formulations.

Effects of molecular weight, stereo configuration of PLA, and processing on the dispersion of multiwalled carbon nanotubes and properties of corresponding nanocomposites

AbstractMultiwalled carbon nanotubes (MWCNTs) were dispersed and distributed via a co‐rotating twin‐screw extruder (TSE) in high (h)‐ and low (l)‐molecular‐weight amorphous and semicrystalline polylactides (PLAs) (aPLA and scPLA, respectively). Effects of PLA molecular weight and D‐lactic acid equivalents content (D‐content), as well as processing parameters, were examined on the MWCNT dispersion quality in PLA. The effectiveness of the MWCNT dispersion in various PLA matrices was investigated using scanning electron microscopy (SEM) and small‐amplitude oscillatory and transient shear flow rheometry in the molten state. The results showed a better dispersion of MWCNTs in the low‐molecular‐weight PLA grades (aPLAl and scPLAl). In addition, better MWCNT dispersion was observed in aPLA grades when processed at a higher temperature of 190°C than at 150°C. At 150°C, while MWCNT bundles in aPLAl could be broken down, a good dispersion could not be achieved in aPLAh due to the lower molecular mobility at such a temperature. The electrical conductivity of the samples was also shown to increase as the MWCNT dispersion was improved. The existence of crystallites in scPLA‐based nanocomposites, however, disrupted the connectivity of the MWCNTs and decreased the final electrical conductivity. The lower molecular weight aPLAl prepared at 190°C showed the highest electrical conductivity (~10−5 S/m) at a low loading of 0.5 wt.% MWCNTs.

Quantified analysis of 2D dispersion of carbon nanotubes in hardened cement composite using confocal Raman microspectroscopy

Dispersion of carbon nanotubes (CNTs) is the critical factor affecting the performance of nanocomposites; however, the quality of CNT dispersion could be indirectly understood due to the limitations of evaluation methods of the dispersion. This study aimed to visualize the macroscopic spatial distribution of CNTs in an as-is hardened cement matrix for the quantification of dispersion. Using a confocal Raman microspectroscopy equipped with an optical microscope, the major phases in cement, hydrates, and CNTs were identified from their characteristic Raman signals to construct the definitive phase map. The dispersion efficiency and heterogeneity were defined to quantify the fraction of CNT-affected region and the unevenness of CNT distribution. The experimental results demonstrate the importance of a well-dispersed stable state in CNT suspension and suggest that it is possible to evaluate the effectiveness of ultrasonication with superplasticizers that have been frequently adopted as a dispersion technique in hardened cement composites.