Anionic Emulsion Research Articles

Impact of rapid-hardening cements on mechanical properties of cement bitumen emulsion asphalt

Cement bitumen emulsion asphalt (CBEA) is obtained by mixing bitumen emulsion, cement, aggregates and filler at ambient temperature. CBEA is thought to be a promising substitute for hot mix asphalt because of its low environmental impact and cost-effectiveness. Disadvantages of this material are the long time required to reach its full strength and the inadequate understanding of the hardening mechanisms. This study aims at accelerating the development of mechanical properties of CBEA by using rapid-hardening cements while at the same time gaining a deeper understanding of the role of cement in CBEA. With this purpose, cold mix asphalt mixtures with cationic and anionic emulsions and different types of cement (ordinary Portland, calcium sulfoaluminate and calcium aluminate cement) were studied by means of isothermal calorimetry, measurements of water evaporation and Marshall tests. The results indicate that both anionic and cationic bitumen emulsions may affect the initial hydration rates of the cements used but have no significant influence on their degree of hydration after a few days. The addition of calcium sulfoaluminate and calcium aluminate cement to CBEA leads to mechanical properties after 1-day curing similar to those obtained with Portland cement after 1-week curing. Cement hydration dominates the strength gain, especially for rapid-hardening cements, and the type of cement influences both the amount of bound water and the rate of water evaporation from the CBEA.

阴离子有机硅乳液的制备

从阴离子有机硅乳液的合成出发，引入活性单体，采用微乳液聚合方法制备成氨基及活性基团改性半透明有机硅微乳液，研究了温度控制、乳化体系、活化物体系等方面对乳液性能的影响，并进行了应用试验。结果证明，制备的阴离子乳液的手感滑弹性较好，特别适用于T/R、T/C混纺织物的浸轧柔软整理工艺。 An active monomer was lent into synthesis of anionic silicone emulsion. Amino group modified silicone translucent micro-emulsion was prepared by micro-emulsion polymerization. We studied temperature control, system and activator system to enhance the properties of emulsion. The results show that the prepared anionic emulsion provides excellent smoothness and better elasticity, especially suitable for the soft finishing process of T/R and T/C blended fabric.

Effects of asphalt emulsion on properties of fresh cement emulsified asphalt mortar

This study evaluates the effects of two types of asphalt emulsion, anionic and cationic emulsions, on the properties of two types of cement emulsified asphalt mortar (CEAM), low-modulus CEAM and high-modulus CEAM, at varying asphalt to cement ratios (A/C). The study focused on the effects of emulsion on the properties of fresh CEAM mixes, including workability, cement hydration, dynamic shear modulus, and phase angle. The workability was evaluated using the flow table test. The cement hydration and dynamic shear rheometer (DSR) tests were performed to investigate the cement hydration development and viscoelastic properties of CEAM mixes. In addition, the uniaxial compressive strength was tested to examine the effects on the properties of hardened CEAM mixes. The laboratory test results show that the workability evidently decreased with the increase in A/C and the adoption of cationic asphalt emulsion. Increase in A/C ratio lowered the cement hydration rate in CEAM. Cationic asphalt emulsion and higher cement content made CEAM stiffer as it exhibited higher complex shear modulus. There was a significant reduction in compressive strength of the mortars with the increase in A/C ratio. Cationic asphalt emulsion was desirable for high-modulus CEAM because it could give CEAM a higher compressive strength than anionic asphalt emulsion at different ages.

Drug-free chitosan coated poly(isobutylcyanoacrylate) nanoparticles are active against trichomonas vaginalis and non-toxic towards pig vaginal mucosa.

The present work reports a non-conventional therapeutic strategy based on the use of vaginally-applied formulations for the treatment of trichomoniasis due to Trichomonas vaginalis without adding a drug. The formulations were based on a thermosensitive pluronic® F127 hydrogel containing mucoadhesive poly(isobutylcyanoacrylate) nanoparticles coated with a mixture of chitosan and thiolated chitosan (75/25 wt%). The nanoparticles were obtained by anionic emulsion polymerization of isobutylcyanoacrylate. The anti-T. vaginalis activity of the formulations was evaluated in vitro. Chitosan-coated nanoparticles showed a strong anti-T. vaginalis activity at 100 μg/mL independently on the proportion of thiolated chitosan. No anti-T. vaginalis activity was reported neither with chitosan-uncoated poly(isobutylcyanoacrylate) nanoparticles nor with chitosan used as a solution. These results suggest that the anti-T. vaginalis activity was related to poly(isobutylcyanoacrylate) nanoparticles but only when they are coated with chitosan. Histological analysis of ex vivo pig vaginal mucosa in contact with pluronic® F127 hydrogel containing poly(isobutylcyanoacrylate) nanoparticles coated with the mixture chitosan/thiolated chitosan (75/25 wt%) did not reveal any toxicity. This study demonstrated that poly(isobutylcyanoacrylate) nanoparticles coated with chitosan were active against T. vaginalis without adding a drug. Besides their anti-T. vaginalis activity, the formulations are non-toxic towards pig vaginal mucosa.

Combined effect of surface-charged latex nanoparticle AHPS and Al2O3 nano-fillers on electrochemical performance of the anionic gel polymer electrolytes PVA/P (MA-co-AHPS)

There have been many studies aimed at improving the ionic conductivity of solid polymer electrolytes (SPEs). Nevertheless, no reports in the literatures can be found on the combined effect of inner-structure of polymer and nano-fillers. In this work, Novel anionic composite gel polymer electrolytes poly (vinyl alcohol)/poly (methyl acrylate–co–sulfonate allyloxy PVA/P (MA–co–AHPS) (PVMS) and series of composite polymer electrolytes PVA/P (MA–co–AHPS)-x wt.% Al2O3 (PVMS-Alx) have been prepared by blending and chemical copolymerization. The physicochemical properties of these polymer electrolytes have been studied in detail by FTIR, TG, SEM and AC analyses. Moreover, maximum conductivity value (1.08×10−3Scm−1) has been achieved by optimizing the inner-structure of the polymer and the content of ceramic filler. The ionic conductivity is found to be greatly dependent on the special spherical structure, anionic emulsion sodium sulfonate allyloxy (AHPS) and nano-sized alumina filler (Al2O3), which can guarantee wider electrochemical window, higher discharge capacity, better interface stability and more excellent cycling performance.

Emulsified Asphalt Residue Recovery and Characterization

A new procedure has been developed for residue recovery of emulsified asphalt. The procedure uses a moisture analyzer balance (MAB). The MAB recovery method is quick and simple compared with traditional recovery procedures such as distillation or oven evaporation. Although the MAB procedure has become an ASTM procedure, there have been a limited number of studies on the rheological properties of the emulsion residues recovered by MAB. This research used a dynamic shear rheometer (DSR) to investigate the rheological properties of MAB specimens. The MAB method was used for several types of emulsions, including cationic and anionic emulsions with several modifications. The MAB method developed in this study addresses the issue of breakdown of polymers during recovery of modified emulsions at high temperatures. The study evaluated the effect of recovery temperature on the recovery time and rheological properties of emulsion residues and proposed a new recovery-characterization procedure. The results show that a preliminary performance grade classification of the emulsified asphalt can be made with the combined MAB-DSR procedure. Furthermore, the study quantified the effect of aging that might occur during the recovery and emulsification process on the rheological properties of the emulsion residues. The combined MAB-DSR procedure is proposed to be a cost-effective alternative method to evaluate the performance of emulsified asphalts.

Influences of superplasticizer, polymer latexes and asphalt emulsions on the pore structure and impermeability of hardened cementitious materials

Three types of polymers commonly used in concrete and mortar (polycarboxylate superplasticizer, polyacrylate latexes and asphalt emulsions) which differ in molecular/particle size from nanometer to micron were employed to investigate their effects on the pore structure of hardened cement pastes and the impermeability of hardened mortars. The pore structure and the impermeability of the hardened ones cured for 7days and 28days were measured by mercury intrusion porosimetry and alternating current impedance, respectively. Results show the incorporation of superplasticizer obviously reduces the average pore size and enhances the impermeability. The polyacrylate latexes also lead to the decline in pore size and consequently the enhanced impermeability at dosage higher than 3%. At the same dosage, latex with smaller polymer particle size is more effective in reducing the average pore size and enhancing the impermeability than that with larger particle size due to its better plasticizing effect. Similarly, asphalt emulsions also facilitate the enhancement in impermeability, and the anionic asphalt emulsion with better plasticizing effects brings about stronger impermeability than the cationic one. It is believed that for superplasticizer, the plasticizing effect is the main controlling factor for the finer pore structure and the enhanced impermeability. In the case of polymer latexes and asphalt emulsions, the plasticizing effect contributes actively at low dosage and the filling effect is dominant at high dosage in terms of declining pore size and augmenting impermeability.

Studies on Ocular and Parenteral Application Potentials of Azithromycin- Loaded Anionic, Cationic and Neutral-Charged Emulsions

Ocular and parenteral application potentials of azithromycin-containing, non-phospholipid-based cationic nanosized emulsion in comparison to the phospholipid-based anionic and neutral-charged nanosized emulsions were investigated. Various physical, chemical, nonclinical toxicity and antimicrobial activity studies (mean droplet diameter, surface charge, creaming index, entrapment efficiency, accelerated, long-term and freeze-thaw cycling stabilities, TLC study, modified hen's egg chorioallantoic membrane (HET-CAM) test, in vitro hemolysis test, in vitro and in vivo myotoxicity, and in vitro antimicrobial activity) were conducted for assessing the potentials of these three types of emulsions. Following autoclave sterilization, all of these emulsions exhibited a nanometer range mean particle diameter (200 ± 29 to 434 ± 13 nm). While the anionic and cationic emulsions did show high negative (-34.2 ± 1.23 mV) and positive zeta potential (42.6 ± 1.45 mV) values, the neutral-charged emulsion did not. Even with 5 freeze-thaw cycles, the cationic emulsion remained stable whereas other two emulsions underwent phase-separation. The hen's egg chorioallantoic membrane test revealed an irritation score value that was higher for the anionic emulsion than for cationic or neutral-charged emulsion. A significantly higher % hemolysis value was also noticed for the anionic emulsion when compared to the % hemolysis value of cationic emulsion (ANOVA, P ‹ 0.05). However, all of the emulsions showed a lesser intracellular creatine kinase (CK) release/plasma CK level in comparison to the positive control (phenytoin) indicating their lesser myotoxicity at the injection site . When compared to anionic and neutral-charged emulsions, the possible controlled drug release from cationic emulsion delayed the in vitro antimicrobial action against H.influenzae and S.pneumoniae.

Efficacy of topical formulations containing Pimenta pseudocaryophyllus extract against UVB-induced oxidative stress and inflammation in hairless mice

Plants rich in antioxidant substances may be a promising strategy for preventing UV-induced oxidative and inflammatory damage of the skin. Pimenta pseudocaryophyllus is native to Brazil and presents flavonoids and other polyphenolic compounds in high concentration. Thus, the present study evaluated the possible effects of topical formulations containing P. pseudocaryophyllus ethanolic extract (PPE) at inhibiting UV-B irradiation-induced oxidative stress and inflammation. PPE was administered on the dorsal skin of hairless mice using two formulations: F1 (non-ionic emulsion with high lipid content) and F2 (anionic emulsion with low lipid content) before and after UV-B irradiation. The following parameters were evaluated in skin samples: edema, myeloperoxidase activity, cytokines levels, matrix metalloprotease-9 (MMP-9) secretion/activity, reduced glutathione (GSH), superoxide anion and lipid peroxidation levels, and mRNA expression for glutathione reductase and gp91phox. The UV-B irradiation increased all parameters, except for IL-10 levels and glutathione reductase mRNA expression, which were not altered, and GSH levels, which were reduced by exposure to UV-B light. Treatments with F1 and F2 containing PPE inhibited UV-B-induced edema formation (89% and 86%), myeloperoxidase activity (85% and 81%), IL-1β production (62% and 82%), MMP-9 activity (71% and 74%), GSH depletion (73% and 85%), superoxide anion (83% and 66%) and TBARS (100% and 100%) levels, increased glutathione reductase (2.54 and 2.55-fold) and reduced gp91phox (67% and 100%) mRNA expression, respectively. F2 containing PPE also increased IL-10 levels. Therefore, this study demonstrates the effectiveness of topical formulations containing PPE in inhibiting UV-B irradiation-induced inflammation and oxidative stress of the skin.

Characterization of Cationic Polyelectrolytes Adsorption to an Anionic Emulsion via Zeta‐Potential and Microcalorimetry

AbstractThe adsorption of cationic polyelectrolytes (PEs) onto anionic silicone emulsion droplets, suspended in a sodium chloride solution is studied via electrophoretic mobility measurements and isothermal titration calorimetry. These model systems are studied to better understand the interactions governing PE adsorption‐induced emulsion flocculation, which is relevant to many industrial applications. Electrophoretic mobility measurements provide critical information for rationalizing the effect of the PE charge density on the loss of stability of silicone emulsions. The interaction strength is calculated from a Langmuir adsorption isotherm determined by a ζ‐potential titration measurement. Microcalorimetry measurements independently validate the adsorption free energy. Emulsion flocculation and coacervation are observed in the visual phase behavior as well as the ζ‐potential titration measurements. The effect of PE charge density shows that PE‐surfactant coacervation is the driving force in these PE‐emulsion systems.

Effect of non–phospholipid-based cationic and phospholipid-based anionic nanosized emulsions on skin retention and anti-inflammatory activity of celecoxib

Context: Celecoxib (CXB, 0.2 g)-loaded anionic and cationic nanosized emulsions were prepared by a well-established combined emulsification method.Objectives: To investigate the effect of non–phospholipid-based cationic and phospholipid-based anionic emulsions on skin retention and anti-inflammatory activity of CXB.Methods: Using Keshary-Chien diffusion cells with cellulose acetate membrane or excised rat skin, in vitro release and skin retention of CXB from solution and emulsions were studied. The anti-inflammatory activity was evaluated by the carrageenan-induced hind paw edema method in Wistar rats.Results: The amount of drug released through artificial membrane has decreased from 122.00 ± 0.70 μg/cm2 for the CXB solution to 55.80 ± 0.70 μg/cm2 for anionic emulsion, and then further decreased to 24.79 ± 0.90 μg/cm2 for cationic emulsion. The JSS value obtained with solution, anionic, and cationic emulsions were 6825.79 ± 920.86, 2513.15 ± 382.71, and 1925.67 ± 147.42, respectively. Cationic emulsion showed a significantly higher level (P ≤ 0.05) of drug accumulation in full-thickness rat skin than anionic emulsion, and a substantially lesser percentage inhibition of edema values compared with both solution and anionic emulsion.Discussion and conclusion: Sustained drug release together with increased skin accumulation and simultaneously decreased skin permeation as observed with cationic emulsion should substantiate its suitability as a topical delivery vehicle for CXB.

Using the pseudophase kinetic model to interpret chemical reactivity in ionic emulsions: Determining antioxidant partition constants and interfacial rate constants

Kinetic results obtained in cationic and anionic emulsions show for the first time that pseudophase kinetic models give reasonable estimates of the partition constants of reactants, here t-butylhydroquinone (TBHQ) between the oil and interfacial region, POI, and the water and interfacial region, PWI, and of the interfacial rate constant, kI, for the reaction with an arenediazonium ion in emulsions containing a 1:1 volume ratio of a medium chain length triglyceride, MCT, and aqueous acid or buffer. The results provide: (a) an explanation for the large difference in pH, >4 pH units, required to run the reaction in CTAB (pH 1.54, added HBr) and SDS (pH 5.71, acetate buffer) emulsions; (b) reasonable estimates of POI and kI in the CTAB emulsions; (c) a sensible interpretation of added counterion effects based on ion exchange in SDS emulsions (Na+/H3O+ ion exchange in the interfacial region) and Donnan equilibrium in CTAB emulsions (Br− increasing the interfacial H3O+); and (d) the significance of the effect of the much greater solubility of TBHQ in MCT versus octane, 1000/1, as the oil. These results should aid in interpreting the effects of ionic surfactants on chemical reactivity in emulsions in general and in selecting the most efficient antioxidant for particular food applications.

Distribution of Cyclosporine A in Ocular Tissues After Topical Administration of Cyclosporine A Cationic Emulsions to Pigmented Rabbits

The aim of this study was to compare the ocular and systemic distribution of cyclosporine A (CsA) in rabbits after the instillation of preservative-free CsA cationic and anionic emulsions. For the single-dose pharmacokinetic (PK) study, rabbits were instilled with 50 μL of the test material. For the multiple-dose PK study, rabbits were instilled twice daily with Restasis or once daily with NOVA22007 for 10 days. At each time point, the cornea, conjunctiva, and whole blood were harvested for CsA quantification. Ocular and systemic distribution were determined after 4 times daily instillations with 50 μL of 3H-CsA cationic and anionic emulsions for 7 days. Restasis was used as a reference in all studies. Single-dose PK data demonstrated that NOVA22007 0.1% and 0.05% delivered higher CsA concentrations to the cornea than Restasis [concentration maximum (C max): 2692, 1372, and 748 ng/g, respectively] and have a better exposition (area under the curve). Conjunctival Cmax values were 1914, 696, and 849 ng/g and area under the curve values were 3984, 2796, and 2515 ng/g · h, for either dose of the cationic emulsions and Restasis, respectively. The multiple-dose PK and the 3H-CsA distribution data demonstrated that the systemic distribution after repeated instillations was low and comparable for all emulsions. These data demonstrate that the CsA cationic emulsions were more effective than Restasis at delivering CsA to target tissues, thus confirming the potential advantage of cationic emulsions over anionic emulsions as vehicle for ocular drug delivery for the treatment of ocular surface diseases.

Effect of early cement hydration on the chemical stability of asphalt emulsion

The effect of pH value, Ca2+ concentration and water loss induced by cement hydration on emulsion stability was investigated by measuring the Zeta potential of asphalt droplets. The microstructure of emulsion was also observed by optical microscope. The results indicate that the chemical stability of cationic emulsion is strongly affected by pH value increase and the addition of nonionic emulsifier improves the alkali resistance property of emulsion. However, the chemical stability of anionic emulsion was slightly improved by pH increase. Ca2+ slightly influences the cationic and anionic emulsions due to its small concentration in the cement paste pore solution. The Zeta potentials of both cationic and anionic emulsions were sharply decreased due to water loss.

Application of anionic asphalt emulsion as an admixture for concrete

Durability of engineering structures made of cementitious composites is a very important issue in the aspect of their reliability in specific exposure classes. This study presents experimental results of selected properties of concretes modified with bituminous admixture in the form of anionic asphalt emulsion (AE) which acts as corrosion inhibitor. Its dosage does not exceed 5% of cement mass (as it is specified for admixtures in the European Standard EN 206-1). The results of technical and structural concrete properties allow to assume that anionic emulsion may in many cases constitute a proper material protection of engineering concrete structures working in specific environments. This study is a continuation of research considering material and structural protection of cementitious composites modified with asphalt admixtures.

Preparation and Properties of Anionic Polymer Emulsion in the Presence of a Reactive Surfactant

Stable polymer emulsion derived from Butyl Methacrylate (BMA), 4-vinyl pyridine (4-VP), vinylidene chloride (VDC) and divinylbenzene (DVB) with different size and distribution were prepared through soapless emulsion polymerization by using a reactive surfactant and a redox initiator. The influences of the quality ratio of the reactive surfactant to the monomers and the dosages of the cross-linking agent on the stability and thermal properties of the emulsion were studied. The obtained polymer nano-particles have higher ξ potential, and the particle sizes have narrow distribution. This polymerization system can give some further understanding on the mechanism of emulsion polymerization .The solid content of the emulsion could be as high as 40% and the particle sizes could be adjusted in the range of 40-300nm. Otherwise, using infrared spectroscopy, size and ξ analyzer, gravitational thermal analysis and differential scanning calorimeter, properties of the emulsion latex were tested. This kind of latex may have applications in the development of water-developable thermal-sensitive material system.

Intestinal permeation enhancement of docetaxel encapsulated into methyl-β-cyclodextrin/poly(isobutylcyanoacrylate) nanoparticles coated with thiolated chitosan

In this study we investigated the potential of mucoadhesive nanoparticles to enhance the intestinal permeability of docetaxel (Dtx). These nanoparticles were composed of methyl-β-cyclodextrin (Me-β-CD) combined with poly(isobutylcyanoacrylate) and coated with thiolated chitosan. In order to encapsulate the highest amount of Dtx into nanoparticles, the anionic emulsion polymerization of isobutylcyanoacrylate was carried out in a solution of Me-β-CD/Dtx inclusion complex. The resulting nanoparticles were spherical with diameters ranging from 200 to 400nm, and positively charged. Depending on the formulation, the encapsulation efficiency of Dtx was 70–80%. In vitro experiments in simulated intestinal medium containing 1% w/v of pancreatin showed that Dtx was gradually released to reach 60% after 24h and 100% after 48h. The capacity of these nanoparticles to enhance the flux of Dtx across the intestinal membrane was then investigated using the Ussing chamber technique. The intestinal permeation of Dtx loaded into nanoparticles was found to be higher than the ethanol control solution of Dtx. Interestingly, when mucoadhesive interactions between nanoparticles and the mucosa were avoided, the intestinal permeation of Dtx significantly decreased, confirming that the mucoadhesion of the nanoparticles was a mandatory condition to enhance the intestinal permeation of Dtx.

Aqueous tape casting of boron carbide ceramic

An environmental friendly aqueous tape casting process has been introduced to fabricate B4C green tapes. Tetramethylammonium hydroxide (TMAH) and a mixture of waterborne epoxy emulsions and anionic aliphatic urethanes emulsions were selected as the dispersant and binder, respectively. The influence of pH value on the zeta potential of ceramic suspensions has been investigated, and the dispersant content added has been optimized based on the rheological behaviors of B4C slurries. The green sheets showed homogeneous microstructure with high flexibility and enough strength for the subsequent cutting and lamination. After sintering at 2100°C, dense B4C ceramics can be achieved. The relative density and the flexural strength of the sintered samples were 96.8% and 636±70MPa, respectively.

Enhanced oil recovery from heavy oil reservoirs utilizing a displacement agent

An oil displacement agent consisting of nonionic and anionic surfactants and emulsion stabilizers has been developed to enhance oil recovery from heavy oil reservoirs. The experimental results show that the proposed displacement agent enhances oil recovery by more than 20 % compared with water flooding and that the emulsion contained in the fluid produced can be easily broken (demulsified). The mechanism of action for the displacement agent is described.

In-vivo pharmacokinetics, tissue distribution and anti-tumour effect of hydroxycamptothecin delivered in oil-in-water submicron emulsions

The aim of this study was to investigate the pharmacokinetics, tissue distribution and anti-tumour effect of hydroxycamptothecin submicron emulsions (HCPT-SEs). HCPT-SEs or HCPT injection (HCPT-I) was administered intravenously into the tail vein of rats or S180 tumour-bearing mice. HCPT-SEs increased the plasma concentration of HCPT compared with HCPT-I at all time points. The AUC(0-∞) , elimination half-life and mean residence time of anionic submicron emulsions containing HCPT (HCPT-ASEs) and cationic submicron emulsions containing HCPT (HCPT-CSEs) were significantly greater than those of HCPT-I (P <0.01). Especially, a prolonged elimination half-life was found for HCPT-CSEs. HCPT-CSEs and HCPT-ASEs resulted in a 7.9-fold and 3.1-fold increase in AUC(0-6h) of tumour compared with HCPT-I, respectively. The targeting efficiency (T(e) ) of HCPT-ASEs and HCPT-CSEs indicated their selectivity to tumour and the T(e) of HCPT-CSEs was significantly higher than that of HCPT-ASEs (P<0.01). The anti-tumour effect studies showed that HCPT-SEs improved the therapeutic efficiency of HCPT compared with HCPT-I. The percentage of tumour growth suppression rate of mice treated with HCPT-CSEs (2.0 mg HCPT eq./kg) increased 2.1 fold compared with that of HCPT-I. Submicron emulsions can alter the pharmacokinetic characteristics and tissue distribution of HCPT, and enhance tumour targeting and anti-tumour activity.