Interfacial Modulus Research Articles

Non-invasive rust detection of steel plates determined through interfacial modulus

Initial methods to detect rust in pipelines have been conducted through invasive probes and sectioning off parts of the facility as the plant is running. These methods greatly increase the costs overall. The need for a feasible solution to this issue lies in the detection of rust formation through a non-invasive method. This study’s objective is to measure rust formation through droplet motion on the outer layer of pipelines. Multiple experiments are conducted using carbon steel sheets whose bottom layer has been exposed to acid for different durations of time. As rust formation in the metal is a voltaic phenomenon, it would mean that the acid corrosion of the bottom layer would adversely affect the top layer of the substrate. Consequentially, droplet motion and the droplet’s contour would change in different corrosive scenarios which we could then detect with novel parameters in our lab. One such parameter is the Interfacial Modulus (GS), which describes the initial resistance of the solid’s outer layer towards the liquid. We can understand this parameter with the aid of the novel device, known as the Centrifugal Adhesion Balance (CAB). As we cause the drop to slide across the substrate at constant normal force condition, we observe the difference in the contour of the drop as it slides across the substrate. The real-time change in contact angles at each edge of the drop, along with its change in external lateral force, causes a change in the GS values, which varies in different corrosive scenarios.

Hydrophobically modified silica nanolaces-armored water-in-oil pickering emulsions with enhanced interfacial attachment energy

HypothesisAnisotropic particles with a high aspect ratio led to favorable interfacial adhesion, thus enabling Pickering emulsion stabilization. Herein, we hypothesized that pearl necklace-shaped colloid particles would play a key role in stabilizing water-in-silicone oil (W/S) emulsions by taking advantage of their enhanced interfacial attachment energy. ExperimentsWe fabricated hydrophobically modified silica nanolaces (SiNLs) by depositing silica onto bacterial cellulose nanofibril templates and subsequently grafting alkyl chains with tuned amounts and chain lengths onto the nanograins comprising the SiNLs. FindingsThe SiNLs, of which nanograin has the same dimension and surface chemistry as the silica nanospheres (SiNSs), showed more favorable wettability than SiNSs at the W/S interface, which was supported by the approximately 50 times higher attachment energy theoretically calculated using the hit-and-miss Monte Carlo method. The SiNLs with longer alkyl chains from C6 to C18 more effectively assembled at the W/S interface to produce a fibrillary interfacial membrane with a 10 times higher interfacial modulus, preventing water droplets from coalescing and improving the sedimentation stability and bulk viscoelasticity. These results demonstrate that the SiNLs acted as a promising colloidal surfactant for W/S Pickering emulsion stabilization, thereby allowing the exploration of diverse pharmaceutical and cosmetic formulations.

Mesenchymal Stem Cells Sense the Toughness of Nanomaterials and Interfaces.

Stem cells are known to sense and respond to the mechanical properties of biomaterials. In turn, cells exert forces on their environment that can lead to striking changes in shape, size and contraction of associated tissues, and may result in mechanical disruption and functional failure. However, no study has so far correlated stem cell phenotype and biomaterials toughness. Indeed, disentangling toughness-mediated cell response from other mechanosensing processes has remained elusive as it is particularly challenging to uncouple Youngs' or shear moduli from toughness, within a range relevant to cell-generated forces. In this report, it is shown how the design of the macromolecular architecture of polymer nanosheets regulates interfacial toughness, independently of interfacial shear storage modulus, and how this controls the expansion of mesenchymal stem cells at liquid interfaces. The viscoelasticity and toughness of poly(l-lysine) nanosheets assembled at liquid-liquid interfaces is characterised via interfacial shear rheology. The local (microscale) mechanics of nanosheets are characterised via magnetic tweezer-assisted interfacial microrheology and the thickness of these assemblies is determined from in situ ellipsometry. Finally, the response of mesenchymal stem cells to adhesion and culture at corresponding interfaces is investigated via immunostaining and confocal microscopy.

Mechanical properties and deformation behaviors of the hydroxyl-terminated polybutadiene and ammonium perchlorate interface by molecular dynamics simulation

The interfacial structure and deformation behaviors have considerable influences on the structural reliability and durability of the hydroxyl-terminated polybutadiene (HTPB) solid rocket propellant. In this work, an all-atom molecular dynamics (MD) simulation was adopted to investigate mechanical properties and damage behaviors of the HTPB and ammonium perchlorate (AP) interface. The modified polymer consistent force field was implanted to describe intra- and intermolecular interactions. The effects of loading rate, temperature, and moisture content on the interfacial strength and tensile curves were discussed. The simulation results show that the interfacial strength and modulus exhibit an increasing tendency when the loading rate increases. However, increasing the temperature and moisture content will lead to a decrease in the interfacial strength. Two interfacial tensile modes distinguished by the mass density curve were adopted and compared to reveal the internal deformation process. The AP-HTPB interfacial deformation initially occurs inside the HTPB bulk due to its lower mechanical strength than the interface and then gradually expands to the interface region. Furthermore, a linear extrapolation based on phenomenological results was used to reveal the discrepancy in scale between experiments and the MD simulation.

Influence of selected gums on the foaming properties of egg white powders: Kinetics of foam formation and baking performance

In this study, the influence of three selected gums including neutral locust bean gum (LBG), guar gum (GG), and anionic xanthan gum (XG) on the foaming and baking properties of egg white (EW) powders were investigated. Results showed that the surface tension, particle size, viscosity and interfacial adsorption modulus of reconstituted EW solutions prepared by EW powders increased with the addition of gums, along with the decrease of surface hydrophobicity, especially in the presence of the anionic XG. The kinetic analysis of foam formation showed that the addition of gums, especially for LBG and GG, were beneficial to the rapid infiltration of air in foam, thus dramatically reducing the whipping time in the preparation of cake batter. Furthermore, the angel cakes prepared by reconstituted EW solutions containing LBG or GG had higher specific volume than fresh EW. These results showed that the addition of neutral gums can improve the baking performance of EW powders by increasing the foaming rate and capacity. This study provided an insight on improving the foaming performance of EW powders by incorporating gums.

Myofibrillar protein microgels stabilized high internal phase Pickering emulsions with heat-promoted stability

This study developed the myofibrillar protein microgel particles (MMP) stabilized high internal phase Pickering emulsions (HIPPEs) with heat-promoted stability. The effect of heat treatment intensity and the heat-promoted stabilization mechanism were investigated by analyzing the microstructure, rheology and interface properties of MMP stabilized HIPPEs. The storage modulus of emulsions displayed an increased trend during the heating up and then cooling down processes. The droplet size of HIPPEs gradually increased with increasing heat treatment intensity (60-121 °C for 5 or 30 min) and still remained stable after heat treatment above 100 °C for 30 min. The heat treatment resulted in the enhancement of the freeze-thaw and centrifugal stability of HIPPEs, implying a dominant contribution to the improvement of emulsion stability. The heat treatment promoted the hydrophobic interactions between MMP at the interface and the gradual formation of interface network structure. Then, it was also observed that a gradual increase in the interfacial expansion modulus (4.6–8.1 mN/m) and the formation of a high strength elastic film. This work provides a facile strategy to improve the stability of protein microgel stabilized HIPPEs, which is beneficial to the development of thermal processing emulsion-based foods.

Demulsification of oily wastewater driven by an amine functionalized cellulose derived from waste cotton textiles

An ANPC demulsifier for oily wastewater (OW) was obtained through amine functionalization of regenerated cellulose derived from waste cotton textiles by a hydrothermal process. ANPC was systematically analyzed through morphology, composition, chemical properties, and interfacial properties. The results showed that ANPC had good interfacial activity and a strong ability to reduce the interfacial tension. The bottle test displayed that the light transmittance of separated water (LT) could reach 92.5% and the corresponding oil removal rate (ORR) was 99.4% when the ANPC dosage was 125 mg/L at room temperature. Importantly, ANPC could be adopted at a wide pH range and high salinity. Also, the possible demulsification mechanism was explored by wettability, interfacial activity, interfacial film self-assembly, dynamic interfacial tension, Zeta potential, elasticity modulus and micrographs. This study provides a biological derived demulsifier with low cost and high efficiency.

Janus nanographene oxide with aerophilic/hydrophilic characteristics for enhancing foam stability in high-temperature reservoirs

Foam technology is currently recognized as one of the most promising technical means to further enhance oil recovery. However, the poor stability of foam in harsh reservoirs with high temperatures limits the further application of foam fluids in oil fields. Based on the Pickering emulsion template method, this paper proposed a synthesis strategy for Janus nanographene oxide with aerophilic/hydrophilic characteristics as a novel foam stabilizer. A high-stability foam reinforced by Janus nanographene oxide was constructed. In addition, this paper clarified the relationship between foam stability and the interfacial characteristics of foam and revealed the probable mechanism by which Janus nanographene oxide enhances foam stability. The results showed that the synthesized Janus nanographene oxide has a typical two-dimensional lamellar structure with an obvious asymmetric characteristic. The negatively charged Janus nanographene oxide showed a small particle size, high ζ potential, high thermal stability, satisfactory amphiphilicity, and high interfacial adsorption, which was beneficial for enhancing foam stability at high temperatures. The foam stability was positively correlated with the interfacial viscoelastic modulus of the foam. Janus nanographene oxide was irreversibly adsorbed onto the gas–liquid interface, which increased the interfacial viscoelastic modulus, especially the interfacial elastic modulus increased from 2.94 mN·m−1 to 16.21 mN·m−1. As a result, the ability of the foam to resist deformation due to external forces was enhanced, which can be reflected in the enhancement of the foam stability. The half-life of foam at high temperature increased from 26 min to 49 min. An appropriate amount of Janus nanographene oxide can form a solid-like film with high mechanical strength on the gas–liquid interface and gradually fill the Plateau boundary of the foam. It can not only effectively reduce the drainage rate of the liquid film but also hinder gas diffusion between adjacent bubbles, which delays the further thinning of the film and coarsening behavior of the foam. Therefore, the constructed reinforced foam can be considered as a promising candidate for further enhancing oil recovery in high-temperature reservoirs, especially for steam channeling control. In addition, this work contributes to a better understanding of the mechanism by which Janus nanomaterials can enhance foam stability and provides theoretical guidance for the further application of foam technology.

Structural characterization, interfacial and emulsifying properties of soy protein hydrolysate-tannic acid complexes

With increasing awareness of health and sustainable dietary pattern, plant-based proteins have shown a growing interest as substitutes for animal proteins. Meanwhile, the non-covalent interaction of protein with natural phenolic compounds can be used to develop functional ingredients. In this work, Alcalase hydrolysates of soy protein isolate (HSPI) were used to fabricate complexes with tannic acid (TA), and their physicochemical properties were investigated and compared with soy protein isolate (SPI) and sodium caseinate (SC) to get insights into the advantage of polyphenol modification. The complex solution showed reduced particle size, higher turbidity, and higher surface charge with increasing TA concentration. The interaction mainly occurred through hydrogen bond and hydrophobic interaction, leading to the unfolding of protein molecular structure. The complexes displayed lower interfacial adsorption activity and reduced interfacial viscoelastic modulus upon increasing TA concentration possibly because of the interference of TA on the diffusion and molecule interaction of protein hydrolysates to form elastic films. Nonetheless, the complex-based emulsion showed enhanced emulsifying stability with small droplet size, superior oxidation stability, high physical stability against heat and freeze-thaw treatment due to the higher surface charge and formation of particle-stabilized interfacial membrane. These findings provide insights for developing plant-based protein with excellent emulsifying properties, which show great potential for application as SC substitute in dairy-free emulsified products.

Effect of EVA wax inhibitor on the W/O emulsion stabilized by asphaltenes and paraffin wax

Ethylene-vinyl acetate copolymer (EVA) is a typical wax inhibitor. It is plausible the EVA could influence the stability of waxy crude oil emulsion because it was influencing both the dispersion state of asphaltenes and the wax precipitation properties. In this paper, the number after the EVA represents the VA content, and the more VA content means the stronger polarity of EVA. Based on the physical characteristics of model crude oil, the emulsion stability, and interfacial properties, the influence of EVA polarity (from EVA 10 to EVA 40) on the stability of model waxy crude oil emulsions (the oil/water volume ratio is fixed at 7:3) containing both asphaltenes and paraffin wax was systematically studied at two different temperatures (30 ℃ and 15 ℃). The results demonstrated that the increment of EVA polarity can not only greatly improve the dispersion state of asphaltenes, but also significantly improve the flowability of model crude oil by changing the morphology of wax crystals. The competitive adsorption of EVA to the interfacial film can be facilitated by the increased polarity of EVA, thus decreasing the asphaltene mass ratio in the interfacial film and then causing the decrease of the interfacial tension and the dilational modulus. The test temperature impacted the stability of the W/O emulsion. At the temperature of 30 ℃ which was higher than the wax appearance temperature (WAT), the interfacial modulus was the main factor affecting the emulsion stability and then increasing EVA polarity caused the emulsion stability to decrease. At the temperature of 15 ℃ below the WAT, due to the formation of large amount of wax crystal particles, the low-temperature flowability of the oil sample was greatly aggravated, which can improve the emulsion stability—increasing the EVA polarity greatly improved the oil rheology, thus leading to a decrease in the emulsion stability. In addition, the size of wax crystals formed in the emulsion was much smaller than those formed in the oil phase, but the amount became larger. We speculated that the emulsified water droplets could serve as wax nucleators, promoting the formation of wax crystal layers around the droplets, which will also favor the emulsion stability at 15 ℃.

An alternative shear lag model for composites with discrete interfaces

Discrete interfaces between different phases are common in natural and engineering materials. A new shear lag model is proposed in this paper to investigate the effects of such interfaces, in contrast to existing shear lag models that only consider a fully bonded interface. The equilibrium equations of discretely bonded platelets in a staggered composite are established, with which the tensile stress and deformation in platelets, interfacial shear stress and effective Young's modulus of the composite are theoretically predicted. It is found that the discrete interface leads to not only a higher average stress level in the platelet but also a smaller effective Young's modulus than those in the composite with a fully bonded interface. The former indicates a higher stress transfer efficiency, while the latter results in a larger strain energy under a given externally applied stress, which should be beneficial for improving the load-bearing capacity and toughness, respectively, of the composite. Such enhancing effects become more significant with decreases in the total interface length, partition number of the interface and spacing between bonding segments. Furthermore, an optimal architecture to achieve a higher stress transfer efficiency and a larger strain energy is found, in which the two neighboring platelets in the representative unit cell are discretely bonded with each other in the middle part instead of at two ends. The present research sheds new light on the influencing mechanisms of discrete interfaces on the mechanical performance of composites, which should be of guiding value for the optimal design of composite interfaces.

Nanoscale analysis of the interface of dip layer/rubber in fiber/rubber composites

The reaction mechanism and the interfacial modulus gradient of the interfacial transition layer between the environmentally friendly dipping system (PAL) and the rubber have not been fully studied. In order to better understand the chemical structures and nano-mechanical properties of the interface between the dip layer and the rubber, we used advanced atomic force microscope (AFM) and nanoscale Fourier transform infrared spectroscopy (nano-FTIR) to perform detailed analysis in this article. The characterization of interfacial nano-mechanical properties and chemical structures is very significant for the illustration of interfacial adhesion mechanism. AFM can effectively characterize the detailed interfacial modulus gradient and the thickness of interface, while nano-FTIR can comprehensively measure the interfacial chemical structures and the distribution of chemical bonds. The results suggest that the thickness of the interface between the PAL dip layer and the rubber matrix is 175 nm, and the crosslinking density of the interfacial layer is high, which explains that the failure location of fiber/rubber composites after pull-out tests occurs on the side of the rubber matrix. Similarly, the microstructure of resorcinol-formaldehyde-latex (RFL) system was also characterized, and the preparation of RFL usually requires carcinogenic and toxic substances such as formaldehyde and resorcinol.

Unfolded Lipase at Interfaces Studied via Interfacial Dilational Rheology: The Impact of Urea

Unfolding can interrupt the activity of enzymes. Lipase, the enzyme responsible for triglyceride catalysis, can be deactivated by unfolding, which can significantly affect the yield of enzymatic processes in biochemical engineering. Different agents can induce lipase unfolding, among which we study the impact of urea as a strong denaturant. Unfolding weakens the rigidity and stability of globular proteins, thereby changing the viscoelastic properties of the protein adsorbed layers. These changes can be detected and quantified using interfacial dilational rheology. The urea-induced unfolding of lipase destructs its globular structure, making it more flexible. The interfacial tension and viscoelastic moduli of lipase adsorbed layers reduce upon the addition of urea in the range of studied concentrations. The results agree with the theory that, upon unfolding, a distal region of the loop and tail domain forms adjacent to the proximal region of the interface. The exchange of matter between these regions reduces the viscoelasticity of the unfolded lipase adsorbed layers. Additionally, unfolding reduces the rigidity and brittleness of the lipase adsorbed layers: the aged adsorbed layer of native lipase can break upon high-amplitude perturbations of the interfacial area, unlike the case for urea-induced unfolded lipase.

Rancidity-induced protein oxidation affects the interfacial dynamic properties and the emulsion rheological behavior of rice bran protein

To improve the practical application of rice bran protein (RBP) prepared from rice bran (RB) with different degrees of rancidity as a stabilizer in emulsion, fresh RB was stored for 0, 1, 5, 7, and 10 d (temperature of 25 °C, relative humidity of 85%) to investigate the effects of RB rancidity on the interfacial dynamic properties and structures of RBP, rheological properties of the O/W emulsion prepared by RBP. RB rancidity-induced moderate oxidation of RBP (prepared from RB storage for 1 d) reduced the particle size (24.36–18.17 nm) and Zeta potential (−13.57 ∼ −14.97 mV) of RBP, while excessive RBP oxidation (prepared from RB storage for 5–10 d) increased the particle size (37.84–68.06 nm) and Zeta potential (−13.40 ∼ −10.6 mV) of RBP. In addition, moderate protein oxidation increased the interfacial pressure, diffusion rate, interfacial expansion modulus of RBP, and emulsion viscoelasticity, while excessive protein oxidation improved the permeability rate and rearrangement rate of RBP. Overall, this study demonstrated that moderate protein oxidation had positive effects on interfacial properties (interfacial dynamic properties and dilatational rheology of interfacial layers) of RBP, which could provide a theoretical basis for mediating the stability and rheology of RBP emulsions by adjusting the degrees of RB rancidity. • Rancidity-induced RBP oxidation changed the K diff , K p and K r of RBP. • RBP oxidation changed the viscoelasticity of interfacial adsorption layers. • RBP oxidation changed the viscosity, G′ and G″ of RBP emulsions.

Interfacial Dilational Rheology of Molecular Films in DC Electric Fields.

We present a novel technique to measure the interfacial dilational rheology of a molecular film adsorbed at a water-oil interface in a direct-current (dc) electric field. A film of a highly polar subfraction of asphaltenes was allowed to adsorb at a water drop interface, surrounded by an organic phase and subjected to a dc electric field. The measurements involved calculations of the dynamic interfacial tension (IFT), while the drop was sinusoidally oscillated, using our in-house axisymmetric drop shape analysis (ADSA) algorithm adapted for electric fields. The amplitude of the IFT waveform over equilibrium IFT and the phase difference from the applied area oscillations were used in the estimation of surface moduli. The asphaltene films were found to become more elastic on increasing bulk concentrations and electric field strengths. However, the effect was not monotonous and observed to be governed by combinations of these parameters. The Lucassen-van den Tempel (LVDT) model was used to further elucidate the experimentally obtained interfacial dilational moduli.

Three Dimensional Printing of Bioinspired Crossed-Lamellar Metamaterials with Superior Toughness for Syntactic Foam Substitution.

Biological materials such as conch shells with crossed-lamellar textures hold impressive mechanical properties due to their capability to realize effective crack control and energy dissipation through the structural synergy of interfacial modulus mismatch and lamellar orientation disparity. Integrating this mechanism with mechanical metamaterial design can not only avoid the catastrophic post-yield stress drop found in traditional architectural materials with uniform lattice structures but also effectively maintain the stress level and improve the energy absorption ability. Herein, a novel bioinspired design strategy that combines regional particularity and overall cyclicity is proposed to innovate the connotation of long-range periodicity inside the metamaterial, in which the node constraint gradient and crossed-lamellar struts corresponding to the core features of conch shells are able to guide the deformation sequence with a self-strengthening response during compression. Detailed in situ experiments and finite element analysis confirm that the rotated broad layer stacking can shorten and impede the shear bands, further transforming the deformation of bioinspired metamaterial into a progressive, hierarchical way, highlighted by the cross-layer hysteresis. Even based on a brittle polymeric resin, excellent specific energy absorption capacity [4544 kJ/kg] has been achieved in this architecture, which far exceeds the reported metal-based syntactic foams for two orders of magnitude. These results offer new opportunities for the bioinspired metamaterials to substitute the widespread syntactic foams in specific applications required for both lightweight and energy absorption.

Study on interface regulation effects of Janus nanofluid for enhanced oil recovery

In this paper, Janus silica nanoparticles (JNS) were fabricated through a facile in-situ modification way. The hydrophilic-hydrophobic balance of Janus silica was regulable by changing the grafting amount of alkyl chains. In contrast to unmodified silica, Janus silica with amphiphilic features similar to surfactants had remarkable interface regulation effects at liquid-liquid and solid-liquid interfaces. JNS nanofluid lowered the interfacial tension and increased the interfacial modulus. It was also found that JNS had excellent emulsifying abilities. Moreover, JNS nanofluid could reverse the strongly oil-wet rock into water-wet, converting the capillary resistance into the driving force. The formation of disjoining pressure and reduced adhesion work of JNS nanofluid facilitated oil film stripping. The core flooding result showed that JNS nanofluid effectively enhanced oil recovery by 15.9 % with low dosages. The finding of this paper would help further understand the interface regulation effects of Janus nanofluid and construct an efficient nanofluid flooding system for enhanced oil recovery.

Controlling Rheology of Fluid Interfaces through Microblock Length of Sequence-Controlled Amphiphilic Copolymers.

Previous studies have demonstrated that films of sequence-controlled amphiphilic copolymers display contact angles that depend on microblock size. This suggests that microblock length may provide a means of tuning surface and interfacial properties. In this work, the interfacial rheology of a series of sequence-controlled copolymers, prepared through the addition of bicyclo[4.2.0]oct-1(8)-ene-8-carboxamide (monomer A) and cyclohexene (monomer B) to generate sequences up to 24 monomeric units composed of (A m B n ) i microblocks, where m, n, and i range from 1 to 6. Interfacial rheometry is used to measure the mechanical properties of an air-water interface with these copolymers. As the microblock size increases, the interfacial storage modulus, G', increases, which may be due to an increase in the size of interfacial hydrophobic domains. Small-angle X-ray scattering shows that the copolymers have a similar conformation in solution, suggesting that any variations in the mechanics of the interface are due to assembly at the interface, and not on solution association or bulk rheological properties. This is the first study demonstrating that microblock size can be used to control interfacial rheology of amphiphilic copolymers. Thus, the results provide a new strategy for controlling the dynamics of fluid interfaces through precision sequence-controlled polymers.

Low-salinity nanofluid – A smart fluid enhanced oil recovery method

This paper proposes a novel Janus graphene nanofluid that enhances the low salinity water oil flooding performance. Two kinds of Janus hydroxylated graphene oxide (JHGO-1 and JHGO-2) were prepared by the high internal phase emulsion method. JHGO nanosheets were well dispersed in low salinity water, and their zeta potential was lower than −30 mV. Compared with JHGO-1, JHGO-2 has more excellent interfacial properties, remarkably reducing 73% of the oil-water interfacial tension and improving the interfacial viscoelastic modulus and shear viscosity. Furthermore, JHGO can form bubble film, interfacial film, and climbing film at the oil/water interface due to its amphiphilic nature, which endows it with intelligent oil-finding properties. JHGO nanofluid alters the rock surface into strong water-wet and changes the capillary force into the driving force of oil flooding. JHGO nanofluid can also rapidly peel crude oil from rock surfaces by reducing adhesion work and forming disjoining pressure. These excellent interfacial properties help low-salinity nanofluid to have a 15.4% enhanced oil recovery at the ultra-low concentration (50 mg/L). This smart fluid flooding lays the foundation for efficient oilfield development.

Interfacial viscoelastic moduli in a weak gel

HypothesisThe measurement of interfacial viscoelastic moduli provides information on the ability of surface-active agents to texture the interface. However, the contribution of the bulk rheology cannot be ignored in particular when the continuous phase exhibits a gel-like behavior, even with low modulus. ExperimentsBetween 2 and 6 g/L, κ-carrageenan aqueous solutions have no significant activities at interfaces. At low concentrations or high temperatures, they behave like Newtonian liquids. Upon heating or cooling, a reversible liquid/gel transition appears with a hysteresis where the rheological behavior can be easily modulated by adjusting κ-carrageenan concentration. The frequency dependence of bulk and interfacial viscoelastic moduli are determined using a conventional shear rheometer and a drop tensiometer with a polyisobutene oil, respectively. FindingsThe effect of concentration and temperature is analyzed and the frequency dependence of interfacial moduli is correlated with those of the bulk. In presence of a gelled κ-carrageenan solutions, an elastic behavior of the interface appears and strengthens as the elastic modulus of the suspended phase is high. It turns out that the oscillating pendant drop method could be a sensitive indicator of the presence of very weak gels, even hardly detected by a shear classical rheometry.