Particle Surface Characteristics Research Articles

Abstract W P404: Magnetic Particle Surface Characteristics Associated with Bradykinin Upregulation: Cause of Hypotension in the Magnetically-Enhanced Diffusion (MED) of Intravenous tPA in Acute Ischemic Stroke Feasibility Trial

Background: Hypotension during treatment was observed in some subjects in a first in man study of MED. The MED system uses an external magnet and magnetic particles to enhance diffusion of intravenous tPA and speed lysis. While free iron and dextran have been associated with hypotension for commercial iron products, the MED magnetic particles use a PEG coating and possesses nearly no free iron. One potential cause for the hypotension was surface charge, similar to acute hypotension reported with dialysis blood filters and liposomes. Methods: Several preclinical experiments were conducted to investigate IgE and complement mediated allergic responses, dose rate vs. dose, baroreflex, and bradykinin upregualtion. Two particle lots were evaluated: Lot A (negatively charged, used in pilot clinical study) and lot B (50% smaller, neutral behavior). For the bradykinin investigation, particle boluses were administered in the presence of a bradykinin blocker (HOE-140) or ACE-I. Mean arterial pressure (MAP) and heart rate (HR) were monitored with acute hypotension defined as a significant drop in MAP over 30s. Results: Studies show a dose-rate relationship to hypotension, not total dose, for lot A only. Baroreflex, IgE, and complement mediated allergic mechanisms were deemed unlikely. While rabbits appeared immune to the response, pigs reliably showed a ~30% MAP decline using the lot A particles, and not for lot B. ACE-I premedication resulted in a stronger response whereas HOE-140 premedication prevented hypotension (Figure). HR appeared to be largely unaffected in the study. Conclusion: It is believed this study represents the first published relationship between bradykinin upregulation and surface characteristics (charge and/or area). Modification of the magnetic particle surface appears to prevent hypotension. The results may provide a new understanding of hypotension reported with other IV iron compounds.

Modified iron-carbon as heterogeneous electro-Fenton catalyst for organic pollutant degradation in near neutral pH condition: Characterization, degradation activity and stability

Polytetrafluoroethylene (PTFE) was firstly used to modify the surface characteristics of Fe-C particles and acted as catalyst to degrade 2,4-dichlorophenol (2,4-DCP) by heterogeneous electro-Fenton (EF) in near neutral pH condition. Fe-C particles before and after PTFE modification, and after 15 times consecutive degradations were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) spectrometry. The modified Fe-C exhibited a good activity for degradation of 120mg/L 2,4-DCP in near neutral pH condition, achieving over 95% removal efficiency within 120min under the conditions of Fe-C 6g/L, current intensity 100mA and initial pH 6.7. In this heterogeneous EF system, a significant synergetic effect between anodic oxidation and single Fe-C micro-electrolysis was obtained, which attributed to the effective EF oxidation at favorable acidic pH condition that triggered by anodic oxidation. 15 times consecutive runs demonstrated the 2,4-DCP degradation efficiency was stable while the iron leaching ratio was relatively low. Account for the catalytic activity, life span and inexpensive cost, the PTFE modified Fe-C was potential for industrial application as a good electro-Fenton catalyst to abate biorefractory pollutants in neutral pH condition.

Effect of dry grinding on chemically modified kaolin

The effect of dry grinding on the morphology and structure of kaolin particles treated with potassium acetate (KAc) and dimethyl sulfoxide (DMSO) has been investigated. After treatment with KAc, the d-spacing of kaolin increased from 0.72 to 1.03, 1.30, and 1.38nm due to the combined effects of humidity and orientation of KAc molecules. The d-spacing was increased to 1.13nm in the case of DMSO treatment. A combination of XRD, TGA, and FT-IR showed that the crystalline structure of kaolin–DMSO and kaolin–KAc were significantly altered by grinding. The intensity of XRD diffraction peaks of ground samples was decreased due to the deterioration of the crystalline structure, and for longer grinding times those peaks almost disappeared. After grinding, the dehydroxylation temperature generally shifted to lower values and a smaller weight loss was observed. The variations of particle size and surface characteristics were also investigated.

3D shape and morphology characterization of sediment particles

In this work, we developed a method to decipher the shape message imprinted in single sediment particles, a method that would reflect the detail information of surface morphology. It uses 2D mathematical descriptions to restore and characterize 3D shape and surface morphology of sediment particles in terms of the “mathematical sediment”, so as to better understand 3D geometric characteristics reflected by single sediment particles. To prevent the simplification of morphology description and overcome the deficiencies of lower-dimensional characteristics, we proposed a concept of “mathematical sediment” in this paper. The mathematical sediment uses image analysis of scanning electron microscope photographs and complex Fourier shape analysis to describe the planar projection shape of sediment particles and further restore the 3D morphology of sediment particles through a certain combination ways. The shapes of sediment particles are controlled using Fourier coefficients to generate a variety of mathematical sediments with various shapes, which allow the realization of the description and analysis of the 3D morphology of sediment particles. The fractal theory is further used to verify the rationality of mathematical sediment. Compared with the traditional method, the mathematical sediment overcomes the lack of particle system and smooth sphere systems and can reproduce 3D irregular surfaces for the morphology analysis. The rationality verification showed that the complex surface morphology of mathematical sediment is basically similar to the surface morphology of natural sediment. The mathematical sediment can reflect the true surface characteristics of sediment particles. The characteristics of shape properties and surface morphology it conveys are consistent with the natural sediment and can be used as a research basis for the further study both in fresh water and marine.

Measuring induction times and crystal nucleation rates

A large variation is observed in induction times measured under equal conditions in 1 ml solutions. Ruling out experimental errors, this variation originates from the nucleation process. The induction time distribution is explained by the stochastic nature of nucleation if the number of nuclei formed is approaching 1 per vial. Accurate heterogeneous crystal nucleation rates were determined from the induction time distributions on a 1 ml scale for racemic diprophylline in two solvents. The difference in nucleation behaviour in the two solvents originates from the energy barrier for nucleation, which is much higher in the solvent in which induction times are much longer. In addition the pre-exponential factor for the crystal nucleation rate in both solvents is rather low compared to predictions using Classical Nucleation Theory. Unfortunately, concentration and surface characteristics of the effective heterogeneous particles are not known which clouds a further molecular interpretation.

Functionalized polystyrene nanoparticles as a platform for studying bio-nano interactions.

Nanoparticles of various shapes, sizes, and materials carrying different surface modifications have numerous technological and biomedical applications. Yet, the mechanisms by which nanoparticles interact with biological structures as well as their biological impact and hazards remain poorly investigated. Due to their large surface to volume ratio, nanoparticles usually exhibit properties that differ from those of bulk materials. Particularly, the surface chemistry of the nanoparticles is crucial for their durability and solubility in biological media as well as for their biocompatibility and biodistribution. Polystyrene does not degrade in the cellular environment and exhibits no short-term cytotoxicity. Because polystyrene nanoparticles can be easily synthesized in a wide range of sizes with distinct surface functionalizations, they are perfectly suited as model particles to study the effects of the particle surface characteristics on various biological parameters. Therefore, we have exploited polystyrene nanoparticles as a convenient platform to study bio–nano interactions. This review summarizes studies on positively and negatively charged polystyrene nanoparticles and compares them with clinically used superparamagnetic iron oxide nanoparticles.

Size and surface modification of amorphous silica particles determine their effects on the activity of human CYP3A4 in vitro

Because of their useful chemical and physical properties, nanomaterials are widely used around the world - for example, as additives in food and medicines - and such uses are expected to become more prevalent in the future. Therefore, collecting information about the effects of nanomaterials on metabolic enzymes is important. Here, we examined the effects of amorphous silica particles with various sizes and surface modifications on cytochrome P450 3A4 (CYP3A4) activity by means of two different in vitro assays. Silica nanoparticles with diameters of 30 and 70 nm (nSP30 and nSP70, respectively) tended to inhibit CYP3A4 activity in human liver microsomes (HLMs), but the inhibitory activity of both types of nanoparticles was decreased by carboxyl modification. In contrast, amine-modified nSP70 activated CYP3A4 activity. In HepG2 cells, nSP30 inhibited CYP3A4 activity more strongly than the larger silica particles did. Taken together, these results suggest that the size and surface characteristics of the silica particles determined their effects on CYP3A4 activity and that it may be possible to develop silica particles that do not have undesirable effects on metabolic enzymes by altering their size and surface characteristics.

Effects of size and surface of zinc oxide and aluminum-doped zinc oxide nanoparticles on cell viability inferred by proteomic analyses.

Although the health effects of zinc oxide nanoparticles (ZnONPs) on the respiratory system have been reported, the fate, potential toxicity, and mechanisms in biological cells of these particles, as related to particle size and surface characteristics, have not been well elucidated. To determine the physicochemical properties of ZnONPs that govern cytotoxicity, we investigated the effects of size, electronic properties, zinc concentration, and pH on cell viability using human alveolar-basal epithelial A549 cells as a model. We observed that a 2-hour or longer exposure to ZnONPs induced changes in cell viability. The alteration in cell viability was associated with the zeta potentials and pH values of the ZnONPs. Proteomic profiling of A549 exposed to ZnONPs for 2 and 4 hours was used to determine the biological mechanisms of ZnONP toxicity. p53-pathway activation was the core mechanism regulating cell viability in response to particle size. Activation of the Wnt and TGFβ signaling pathways was also important in the cellular response to ZnONPs of different sizes. The cadherin and Wnt signaling pathways were important cellular mechanisms triggered by surface differences. These results suggested that the size and surface characteristics of ZnONPs might play an important role in their observed cytotoxicity. This approach facilitates the design of more comprehensive systems for the evaluation of nanoparticles.

A novel solventless coating method to graft low-molecular weight polyethyleneimine on silica fine powders

The overall objective of the present study was to modulate the surface characteristics of aerogel-like submicron and nanometric particles by coating them with polyethyleneimine (PEI) to suit specific biological applications. A new process for the covalent grafting of low-molecular weight PEI chains has been described, based on the use of compressed CO2 as the initiator of the ring opening polymerization of the ethyleneimine monomer, which was performed in the presence of silica particles. Coating was done at low pressure and temperature and in the absence of any organic solvent. Obtained materials were compared with a product prepared following the standard soaking procedure for PEI coating. Materials were characterized regarding composition, structure, surface charge, particle size, morphology, and drug release. The developed process led to the covalent grafting of low-molecular weight PEI on the silica surface, which conferred an increased thermal stability for the coating and low cytotoxicity to the particles. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2760–2768

Effect of the Particle Surface on Oil Recovery from Petroleum Sludge

The surface characteristics of solid particles found in two petroleum sludges were studied, along with their effect on oil recovery. The particles were classified into three types based on their microstructures and settling behavior during centrifugation. Wettability of sludge particles and modified quartz was comparatively investigated by the sessile drop method; solids from petroleum sludge were found to have a contact angle close to that of acidified quartz. When the contact angle decreased from 135.1° to 85.8° and 16.9° in unmodified, acidified, and alkylated quartz, respectively, the oil residue following centrifugation increased from 0.9 to 5.2 and 10.0%. Solids found in petroleum sludge are more hydrophobic than solids from oil sand. Pretreatment methods that can decrease the oil–solids interaction, such as anti-alkylation, will improve oil recovery from petroleum sludge.

Effects of Humic Acid on Surface Characteristics and Hydrodynamic Properties of Alum-TiO<sub>2</sub> NPs Flocs

In order to understanding of the fate and transport of TiO2 nanoparticles (NPs) in the water treatment process, this study focused on the particle surface characteristics and hydrodynamic properties at different humic acid (HA) concentration, using aluminum sulfate (AS) as a coagulant. The changes of zeta potential of humic acid capped TiO2 NPs and flocs were measured by Malvern Zetasizer nanoZS. The surface functional group of flocs was investigated using FT-IR spectra. The growth velocity of alum-TiO2 NPs flocs were determined using a small-angle light scattering technique during the coagulation process.Experimental results indicated that the zeta potential of alum-TiO2 NPs flocs surface after adsorption of humic acid was related with humic acid concentration. Adsorption of humic acid resulted in more negative electrophoresis on the surface. Size and growth velocity of alum-TiO2 NPs flocs were estimated at different humic acid concentration. It was found that the flocs growed were faster in the presence of humic acid, while humic acid had adverse influences on the growth of alum-TiO2 NPs flocs.

Application of pH, ORP, and DO monitoring to evaluate chromium(VI) removal from wastewater by the nanoscale zero-valent iron (nZVI) process

Abstract The reduction of Cr(VI) by the nZVI particles seriously depends on not only the nZVI dosages but also the surface characteristics of nZVI particles caused by different syntheses processes. Therefore, to control the nZVI process only based on the nZVI dosage may not reliable. In this study, a nanoscale, zero-valent iron (nZVI), batch process was used to remove hexavalent chromium Cr(VI) from wastewater. For initial Cr(VI) concentrations of 5, 10, and 20 mg/L, Cr(VI) removal efficiencies were as high as 99% when the nZVI doses were around 0.08, 0.25, and 0.55 g/L, respectively. It was noted that the monitoring of pH, ORP, and DO in the reactor presented good correlations with the Cr(VI) removal efficiencies. Therefore, the monitoring of pH, ORP, DO, the initial Cr(VI) concentration were applied to evaluate the Cr(VI) removal efficiencies. The BPN (Back-Propagation Neural) model provided much more precise predicted Cr(VI) removal efficiencies than the regression models, with the correlation coefficients (R2) of 0.99, 0.99, and 0.97 for contact times of 30, 60, and 90 min, respectively. As a result, the monitoring pH, OPR, and DO have good capabilities to evaluate the Cr(VI) removal efficiencies, which have high potential for use in controlling the nZVI process for the removal of Cr(VI) from wastewater.

Impact of Biochar on Water Holding Capacity of Two Chinese Agricultural Soil

Adding biochar to agricultural soil has been suggested as an approach to enhance soil carbon sequestration. Biochar has also been used as a soil amendment to reduce nutrient leaching, reduce soil acidity and improve water holding capacity. Walnut shells and woody material are waste products of orchards that are cheap, carbon-rich and good feedstock for production of biochar. The effectiveness of biochar as an amendment varies considerably as a function of its feedstock, temperature during pyrolysis, the biochar dose to soil, and mechanical composition. Biochar was produced from pyrolysis of walnut shell at 900 °C and soft wood at 600 to 700 °C. We measured the effect of these different parameters in two types of agricultural soil in Jilin and Beijing, China, a silt clay loam and a sandy loam, on the soils’ particle size distribution and water retention characteristics. Biochars with two different doses were applied to each soil type. Soil field capacity and permanent wilting point were measured using a pressure plate extractor for each combination of biochar and soil type. The results show that the effect of biochar amendment on soil water retention characteristics depend primarily on soil particle size distribution and surface characteristics of biochar. High surface area biochar can help raise the water holding capacity of sandy soil.

Preparation and characterization of controlled release poly-ɛ-caprolactone microparticles of isoniazid for drug delivery through pulmonary route

In the present investigation inhaled isoniazid microparticles (IM) and isoniazid polymeric microparticles (INH-PM) using poly-ɛ-caprolactone polymer were prepared through spray drying techniques. The purpose of this investigation is to evaluate lung deposition of IM and INH-PM through cascade impaction study. The drug release of IM and INH-PM was studied using simulated lung fluids at pH7.4 representing the interstitial site and at pH4.5 representing phagocomal site after alveolar macrophage uptake. The kinetic models had also been applied providing the drug release kinetics for IM and INH-PM in simulated lung fluids at pH7.4 and at pH4.5. The results of the particles size and surface characteristics showed the spherical shape and 1–5μm size of IM and INH-PM prepared using spray drying which can be suitable for pulmonary drug delivery. The cascade impaction study with mass median aerodynamic diameter ranging from 1.9 to 4μm confirmed the inhaled characteristics of IM and INH-PM with providing the deep lung deposition where tubercular bacilli reside. From in vitro drug release studies done using simulated lung fluids and goodness of fit with kinetic model applications, it can be concluded that the prepared poly-ɛ-caprolactone microparticles of isoniazid provided the advantage of controlled release characteristics deep inside the lung where tubercular bacilli reside and as suitable for pulmonary drug delivery it may help in improving treatment of tuberculosis through direct administration to site of action.

Study on preparation and thermal conductivity of high stability magnetorheological fluids

A surface modifier, which has lipophilic groups and chelating groups, was synthesized, and used to modify the surface characteristics of carbonyl iron particles and prepare composite magnetic particles (CMPs). Then a set of oil-based magnetorheological (MR) fluids based on the CMPs were prepared. Finally, the relationship between thermal conductivity and concentration of MR fluids were studied, and an analysis model on thermal conductivity and concentration of MR fluids was built. The result shows that there is a linear correlation between thermal conductivity and concentration of MR fluids, namely keff = 0.0245 Φ − 0.08 and keff/kf = 0.167 Φ − 0.53 (10 ≤ Φ ≤ 50). Applying this model, the concentration variation of the MR fluids can be acquired on the basis of the thermal conductivity variation, and the model can be used to evaluate the sedimentation stability of the MR fluids.

Comparative Study of Chemically and Mechanically Activated Clay Pozzolana

Burnt clay pozzolana produced from a clay deposit at Mankranso in Ghana has been activated by mechanical means through roll milling and ball milling as well as chemically by the addition of 1% - 4% m/m Na2SO4. The pozzolana sample was chemically suitable with total SiO2 + Al2O3 + Fe2O3 content ≥70% as stipulated by the ASTM C 618 standard. The particle sizes, surface characteristics and specific surface areas obtained by the types/degrees of milling were analyzed and their effect on the strength development of Portland pozzolana cement mortar cubes prepared from the pozzolana samples was evaluated. Compressive strengths obtained showed that the activated pozzolana could be used to replace up to 40% ordinary Portland cement (OPC) and satisfy the EN 197-1 and ASTM C 595 standard requirements. Comparatively, the chemically activated pozzolana cement mortars attained higher compressive strengths than the mechanically activated pozzolana cement mortars at equal ages of tests and the same pozzolana content levels. The chemically activated pozzolana cement mortars attained higher 2 day strengths than OPC at sulphate concentrations of 3% and 4% for all pozzolana content levels between 30% - 40%. SEM image and insoluble residue in HCl of a 2 day old chemically activated pozzolana cement paste confirmed dissolution of fine pozzolana particles in the alkaline media which influenced higher early age strengths. The highest 28 day compressive strength of 54.2 MPa was obtained at 4% sulphate concentration and 30% pozzolana content for the chemically activated pozzolana. The highest 28 days compressive strength for the mechanically activated pozzolana was 35.6 MPa—obtained for the roll milled product at 30% pozzolana content. Standard consistence of the pozzolana cement pastes increased with increasing pozzolana fineness and pozzolana content. Increasing Na2SO4 concentration however had no effect on standard consistence. Setting times decreased with increase in both fineness and sulphate concentration. The EN 197-1 standard for initial setting time was satisfied by the chemically activated pozzolana cement mortars at all pozzolana content levels. Pozzolana samples activated by roll milling and 36 h ball milling had faster initial setting times than the EN 196-1 standard at all pozzolana content levels beyond 30%. The ASTM C 595 requirement for initial set was however satisfied at all pozzolana content levels.

THEORETICAL AND EXPERIMENTAL PACKING DENSITY STUDY OF HYDROXYL TERMINATED POLYBUTADIENE-AMMONIUM PERCHLORATE BASED PROPELLANT AND ITS INFLUENCE ON BURNING RATE

A model that gives the particulate composition with maximum packing density and minimum viscosity for highly loaded trimodal hydroxyl terminated polybutadiene-ammonium perchlorate (HTPB-AP) based composite propellant was developed by using the packing density concept. The theoretical model developed by Furnas was utilized to predict particulate composition for maximum packing density. The apparent density of each component of trimodal propellant was determined by tapped density analyzer. The void fractions of the components were calculated from the apparent volumes of the component sizes and pre-known particle densities. Using the void fractions of AP components, the optimum size distribution was gathered by Furnas' method. Least-squares technique was used to test the closeness to the optimum size distribution. The fractions of solid components were calculated for the maximum packing and minimum viscosity. The model was tested by rheological characterization of uncured propellant with the predetermined fractions of components. The variation of viscosity with overall void fraction of the propellant was obtained. For trimodal concentrated suspension of two propellants containing the same mean particle size and size distribution of AP particles from different suppliers, different mix viscosity values were obtained due to different shape and surface characteristics of particles shown by scanning electron microscopy analysis. The effect of both packing density and viscosity on the burning rate of propellant was also explored. It was realized that not only average particle size, but also void fraction of AP particles, were important parameters affecting burning rate and better packing changed ballistic properties of propellant.

Synthesis and Characterization of Lipid Immuno-Nanocapsules for Directed Drug Delivery: Selective Antitumor Activity against HER2 Positive Breast-Cancer Cells

Lipid nanocapsules (LNC) are usually developed as nanocarriers for lipophilic drug delivery. The surface characteristics of these colloidal particles are determinant for a controlled and directed delivery to target tissues with specific markers. We report the development of immuno-nanocapsules, in which some antibody molecules with different immuno-specificity are conjugated to the nanocapsule surface, offering the standardization of a simple method to obtain vectorized nanosystems with specific recognition properties. Nanocapsules were prepared by a solvent-displacement technique, producing an oily core coated by a functional shell of different biocompatible molecules and surface carboxylic groups. Three different antibodies (one a specific HER2 oncoprotein antibody) were conjugated with these nanoparticles by the carbodiimide method, which allows the covalent immobilization of protein molecules through carboxylic surface groups. The immuno-nanocapsules were completely characterized physico-chemically via electrokinetic and colloidal stability experiments, confirming the correct immobilization of these antibody molecules on the colloidal nanoparticles. Also, additional immunological analyses verified that these IgG-LNC complexes showed the expected specific immuno-response. Finally, different healthy and tumoral breast-cell lines were cultured in vitro with Nile-Red-loaded and docetaxel-loaded HER2 immuno-nanocapsules. The results indicate that our immuno-nanocapsules can increase their uptake in HER2 overexpressing tumoral cell lines.

Wear Particle Characterization and Severity Evaluation of Perodua Myvi 1.3L Automatic Transmission (AT) Fluid

s. This paper investigates the characteristic and severity level of both wear and wear particles occurred in Perodua MyVi 1300cc automatic transmission (AT) mechanism via wear particle analysis approach. The analyses deployed were based on ferrographic and surface roughness analysis. The work of analysis strictly conducted on automatic transmission fluid (ATF) Perodua original equipment manufacturer (OEM) (ATF-3) series via continuous endurance dynamometer basis at the operating speed of 3000rpm. The operating mileage tested ranged from 0km up to 10,000km maximum operating distance. The wear particle generated at each operating mileage of 1,500km, 3,000km, 4,500km, 7,000km and 10,000km was accordingly analyzed morphologically and qualitatively. Ferrographic analysis is by principal has been recognized as one of the most reliable analysis incorporated with wear particle analysis (WPA) concern [1]. In concern of this study, it is applied to examine the morphology, mode and characteristic of wear particles generated. The surface roughness analysis meanwhile conducted to qualitatively evaluate and predict the wear condition of components within the AT mechanism via qualitative surface texture analysis of the wear particles. The outcome from the investigation done on the wear particles surface characteristics could interpret the wear behaviour and progress (stage/phase) as the surface characteristics of the wear particles do depict the surface characteristics of the wear components [2, 3].

ELASTOMERIC COMPOSITES BASED ON NANOSPHERICAL PARTICLES AND CARBON NANOTUBES: A COMPARATIVE STUDY

ABSTRACT The reinforcement of elastomeric materials by addition of mineral fillers represents one of the most important aspects in the field of rubber science and technology. The improvement in mechanical properties arises from hydrodynamic effects depending mainly on the amount of filler and the aspect ratio of the particles and also on polymer–filler interactions depending on the surface characteristics of the filler particles and the chemical nature of the polymer. The past few years have seen the extensive use of nanometer-scale particles of different morphologies on account of the small size of the filler and the corresponding increase in the surface area that allow a considerable increase in mechanical properties even at very low filler loading. Among these nanoparticles, spherical particles (such as silica or titania) generated in situ by the sol-gel process and carbon nanotubes are typical examples of materials used as a nanosize reinforcing additive. Specific features of filled elastomers are discussed through the existing literature and through results of the author's research based on poly(dimethylsiloxane) filled with spherical silica or titania particles and on styrene–butadiene rubber filled with multiwall carbon nanotubes. The reinforcing ability of each type of filler is discussed in terms of morphology, state of dispersion (investigated by transmission electron microscopy, atomic force microscopy, small-angle neutron scattering), and mechanical and electrical properties. In addition, the use of molecular spectroscopies provides valuable information on the polymer–filler interface. Spherical silica and titania spherical particles are shown to exhibit two distinct morphologies, two different polymer–filler interfaces that influence the mechanical properties of the resulting materials. The superiority of carbon nanotubes over carbon black for mechanical reinforcement and electrical conduction is mainly attributed to their large aspect ratio rather than to strong polymer–filler interactions. The use of hybrid fillers (carbon nanotubes in addition to carbon black or silica, for example) has been shown to give promising results by promoting an enhancement of mechanical and electrical properties with regard to each single filler.