Latex Emulsion Research Articles

Sorption of cesium radionuclides with composite carbon fibrous materials

Sorption of composite sorbents produced by a combined method of thermal treatment and electrochemical and chemical deposition of transition metal ferrocyanides stabilized with latex emulsions onto a fibrous carbon matrix for cesium radionuclides was studied.

Attributes of the latex emulsion processing and its role in morphology and performance in paints

This article explores the influence of process variation and neutralization of itaconic acid (IA) on polymer properties and paint performance. The study elaborated how the reaction pathway changes the acid distribution in the latexes. The study also investigated the influence on paint performance of degree of neutralization of IA before its incorporation into emulsion. The acid distribution study was done through the conductometric titration method. Latex film properties were studied through differential scanning calorimeter (DSC) and minimum film forming temperature (MFFT). These latexes were formulated in the corresponding paint and study was done using scanning electron microscopy (SEM), which was further correlated with the performance properties of the paint such as scrub, gloss, whiteness and contrast ratio.

Layer-by-Layer Synthesis of Multilayer Core−Shell Latex and the Film Formation Properties

Polymer latex particles were synthesized with multilayer core-shell structure via surface cross-linking emulsion polymerization. The latex core is coated with a five-layer shell. The polymerization was done in a semicontinuous fashion monitored by a dynamic laser scattering (DLS). The copolymer in each layer is designed with alternating high and low glass transition temperature (T(g)). Divinylbenzene (DVB) was added as the cross-linking agent in the synthesis of the "hard" layers to prevent the molecular diffusion from the adjacent "soft" layers. The layer-by-layer increment on the latex core is proved by the alternating changes on the film-formation capabilities of different latex emulsions at room temperature in correspondence with the variance in the T(g) of the outermost polymer layer. The detailed morphologies of the films formed by the latex with different number of layers were characterized by atom force microscopy (AFM). The deformation of the latex particles is largely depended on the nature of the polymer in the outermost layer of the latex particles. Further characterization carried out by multifrequency temperature-modulated differential scanning calorimetry (TOPEM-DSC) confirmed the layer-by-layer structure of the particles, although the molecular redistribution and the interlayer structures were observed. The work provides a routine toward the synthesis of multilayer polymer latexes.

Colloid stable sorbents for cesium removal: Preparation and application of latex particles functionalized with transition metals ferrocyanides

In this paper we suggest a principally new approach to preparation of colloid stable selective sorbents for cesium uptake using immobilization of transition metals (cobalt, nickel, and copper) ferrocyanides in nanosized carboxylic latex emulsions. The effects of ferrocyanide composition, pH, and media salinity on the sorption properties of the colloid stable sorbents toward cesium ions were studied in solutions containing up to 200g/L of sodium nitrate or potassium chloride. The sorption capacities of the colloid sorbents based on mixed potassium/transition metals ferrocyanides were in the range 1.3–1.5molCs/mol ferrocyanide with the highest value found for the copper ferrocyanide. It was shown that the obtained colloid-stable sorbents were capable to penetrate through bulk materials without filtration that made them applicable for decontamination of solids, e.g. soils, zeolites, spent ion-exchange resins contaminated with cesium radionuclides. After decontamination of liquid or solid radioactive wastes the colloid-stable sorbents can be easily separated from solutions by precipitation with cationic flocculants providing localization of radionuclides in a small volume of the precipitates formed.

Fix-a-flat

IT’S ONE OF a driver’s worst nightmares. You hear or feel a pop under your car while driving down the highway. You stop, get out, and inspect, only to see a tire is flat. Great. What now? If you aren’t in a position to change the tire, or never learned how, there’s a solution: spraying an inflator and sealant into the tire from an aerosol can. The handy product is best known under the brand name Fix-A-Flat. For all its instant gratification, this product is remarkably simple. It uses a liquefied propellant to inflate the tire while a latex emulsion foams to plug the leak. Although a gas at room temperature, the propellant becomes a liquid when compressed into the can, explains Jiafu Fang, senior product development scientist for Shell Global Solutions, which has owned the Fix-A-Flat brand for close to a decade. When released from the can, the propellant evaporates. The propellant in ...

Survey of chemical residues and biological evaluation of photochemically pre-vulcanized surgical gloves

Latex allergies arise from the presence of latex proteins as well as noxious rubber additives (mainly accelerators and activators used in conventional sulfur-accelerated vulcanization processes) in medical devices (e.g., medical gloves, catheters) made from natural rubber latex. As a new approach the ultraviolet (UV) light-initiated pre-vulcanization of natural rubber latex makes efficient cross-linking feasible without using any toxic, mutagenic, or irritating chemicals. The cross-linking in the latex particles is accomplished via the thiol-ene addition reaction in the presence of a polyfunctional thiol and a photoinitiator. The new process is carried out in a falling film photoreactor on a pilot scale which provides a continuous irradiation of the latex emulsion. The UV technique is suitable for an easy up-scaling and represents the entrance into large-volume industrial production. The surgical gloves are then made by a conventional coagulant dipping process comprising good physical properties and high ageing stabilities. The aim of this study was to evaluate the biological properties and skin compatibility of UV-pre-cured gloves in skin sensitization, skin irritation studies, and cytotoxic tests. In addition the biologically available chemical residues in the gloves were characterized by UV–visible spectroscopy, elementary analyses, and high-performance liquid chromatography coupled with mass spectroscopy. The results of the studies revealed that UV-cross-linked surgical gloves exhibit good skin compatibility together with low cytotoxicity and residual chemical levels in the range of 60 and 120 μg/gglove.

Detection of coalescing agents in water-borne latex emulsions using an environment sensitive fluorescent probe

In this paper we report the determination of partitioning of coalescing agents (organic co-solvents) in water-borne latex emulsions by means of a fluorescence method. An environment-sensitive fluorescent probe was copolymerized via emulsion polymerization. The presence of organic co-solvents inside the polymer particles is revealed by the photophysical properties of the probe. In particular, the position of the fluorescence emission maximum of co-polymerized can be used to measure the amount of coalescing agent present in the polymer particles. The spectral shifts are shown to be due to the softening of the matrix, rather than to solvation of the probe by the added co-solvent.

Rheological Behavior of Emulsion Residues Produced by Evaporative Recovery Method

The increasing use of surface treatments has generated a need for the development of specifications and test methods for performance of construction and in-service properties of emulsions. A major impediment in characterizing emulsion is the establishment of a generally accepted residue recovery method. ASTM recently approved a procedure for a low-temperature evaporative recovery method. It involves consecutive 24-h curing periods at 25°C and 60°C in a forced-draft oven. Initial rheological evaluation of emulsion residues indicates that residue properties far exceed those of the unaged base binder and are closer to those of aged materials. Also, concerns have been expressed about the length of this procedure and the possibility for reducing the time required. This study focused on evaluating whether the full 48-h curing period is required and identifying the cause of different behaviors relative to base binders. Evaluation was conducted at high and intermediate temperatures on emulsion residues and base binders subjected to different aging conditions, with the dynamic shear rheometer. The study included neat and polymer-modified base asphalts, and latex, polymer-modified, and conventional cationic rapid set emulsions. Results indicate that oxidative aging contributes significantly to the change in rheology with time of curing, compared with unaged base binder. Especially for modified emulsions, the full 48-h curing period is needed for full development of rheological properties. However, the properties should be compared with short-term aged binders rather than unaged binders. Results support the ASTM method but suggest that residue be considered rolling thin-film oven-aged material rather than unaged material.

Polymeric N-Halamine Latex Emulsions for Use in Antimicrobial Paints

A new N-halamine monomer, N-chloro-2,2,6,6-tetramethyl-4-piperidinyl methacrylate (Cl-TMPM), was synthesized and used to prepare water-based polymeric N-halamines by emulsion polymerization. The chemical structures of the samples were characterized with Fourier transform IR, (13)C NMR, UV/vis, and differential scanning calorimetry analyses. Upon the addition of a small amount of the polymeric N-halamine latex emulsions into commercial water-based latex paints as antimicrobial additives, the new paints provided potent antimicrobial activities against Staphylococcus aureus (S. aureus; Gram-positive bacteria), methicillin-resistant S. aureus (MRSA; drug-resistant Gram-positive bacteria), vancomycin-resistant enterococcus (VRE; drug-resistant Gram-positive bacteria), Escherichia coli (E. coli; Gram-negative bacteria), Candida tropicalis (C. tropicalis; fungi), MS2 virus (15597-B; virus), and Stachybotrys chartarum spore (S. chartarum; mold), and they successfully prevented biofilm formation and development. The antimicrobial functions of the new paints were long-lasting for more than 1 year under normal in-use conditions, easily monitorable by a simple potassium iodine/starch test, and readily rechargeable if the functions were accidentally lost as a result of challenging conditions such as heavy soil, flooding, etc.

Preparation and Properties of a Waterborne Contact Adhesive Based on Polychloroprene Latex and Styrene-Acrylate Emulsion Blend

Environmental protection and legislative pressure to eliminate the use of solvents in the adhesive industry have inspired the search for safer alternatives. In the area of contact adhesives, the waterborne route has proved to be of particular interest. Based on the synergistic effect of polychloroprene latex and styreneacrylate emulsion, a waterborne contact adhesive consisting of polychloroprene latex (PCL) and styreneacrylate emulsion (SAE) blend has been developed. In order to blend PCL with SAE easily and to accelerate the drying rate of the adhesive, boric acid was chosen for use in the PCL/SAE blend system. Effects of boric acid and SAE content on the properties of PCL/SAE blends, such as pH value, storage stability and set time, were investigated. At the same time, the effect of SAE content on the mechanical properties of PCL/SAE blend films was studied. The morphology of blend films was characterized by Atomic Force Microscopy. The adhesive performance of the waterborne contact adhesive was evaluated by peel and shear tests. The results showed that when the waterborne contact adhesive formulation contained 40 wt% styrene-acrylate emulsion (dry weight) and 1.25 wt% boric acid, it had a good shelf-stability, its set time was 5 min, and the blend film with this formulation was ductile and flexible with reasonably good tensile strength and very high elongation at break. And the blend films showed structure with a sea–island morphology. The waterborne contact adhesives derived from PCL/SAE blends were found to be comparable to the commercially available solvent-based contact adhesives. The synergistic effect of polychloroprene latex and styrene-acrylate copolymer emulsion was also discussed.

Spectroscopy measurements for determination of polymer particle size distribution

Polymer and copolymer emulsion lattices based on styrene and butyl-metacrylate monomers are commercially important for many paints, adhesives, and coatings applications. The latex properties depend strongly on the copolymer composition, and particle size distribution, which in turn is function of the preparation of the latex and on the formulation of the emulsion designed for the particular application. This paper describes the implementation of multiwavelength spectroscopy measurements for size and distribution of the latex emulsions. The quantitative interpretation of the transmission spectrum is performed in the portion where no absorption is present (300–820 nm) leading to reliable estimated of particle size populations in the range of 0.02–20 μm. Particle size and particle size distribution of polymers and copolymers as function of reaction time and emulsion formulation are found in agreement with Smith Ewart (case 2 kinetics). The possibility of obtaining information from a single multiwavelength measurement makes UV–Vis spectroscopy a powerful tool for characterization of dispersed systems.

Preparation of Al(OH)3/PMMA nanocomposites by emulsion polymerization

AbstractAl(OH)3/PMMA nanocomposites were prepared by the emulsion polymerization of methyl methacrylate (MMA) in the presence of surface‐functionalized Al(OH)3 particles. Nanosized Al(OH)3 particles were previously functionalized with a silane coupling agent, 3‐(trimethoxysilyl) propyl methacrylate (γ‐MPS), which was confirmed by FT‐IR and XRF analysis. The average size of seed particles was around 70 nm, and the density of the coupling agent on the particles was calculated to be 8.9 µmol m−2. The emulsion polymerization was attempted at relatively high solid content of 40–46 wt%. The ratio of the seed particles to MMA had a strong influence on the stability of latex as well as the morphology of composites. Nanocomposites where several PMMA nodules were attached on the surface of Al(OH)3 core were produced with stable latex emulsion when the weight percents of Al(OH)3 to MMA were below 20. In the case of higher ratio of 30%, however, the latexes became unstable with an aggregation, and the product morphology was in the shape of large composite. Thermogravimetric analysis showed an improved thermal stability of PMMA composites with the incorporation of Al(OH)3 nanoparticles. Copyright © 2008 John Wiley & Sons, Ltd.

Effect of polymer cement modifiers on mechanical and physical properties of polymer-modified mortar using recycled artificial marble waste fine aggregate

Various polymer-modified mortars using recycled artificial marble waste fine aggregate (AMWFA) were prepared and investigated for the purpose of feasibility of recycling. Styrene–butadiene rubber (SBR) latex and polyacrylic ester (PAE) emulsion were employed as polymer modifier, and compared each other. The replacement ratio of AMWFA was also changed to investigate the effect of it on physical properties. Adding polymer cement modifier into mortar reduced water–cement ratio, and PAE was the more effective polymer cement modifier to reduce water–cement ratio than SBR. PAE emulsion-modified mortar increased the air content entrained as the proportion of PAE was increased. There was little difference in water absorption between SBR latex and PAE emulsion. The compressive strength decreased in the presence of polymer cement modifiers compared to that of no polymer cement modifiers, but the compressive strength of 20% of polymer–cement ratio was higher than that of 10%. After the hot water resistance test, both compressive strength and flexural strength were decreased.

The Influence of Lubricating Agents on the Formation of a Film of a Styrene/Butadiene Latex

The interactions between paper coating lubricants and a carboxylated styrene/butadiene latex emulsion and their effect on latex film morphology have been studied. Calcium stearate, non-ionic polyethylene emulsion and organic triglyceride lubricants showed different interaction characteristics with the latex emulsion according to viscosity, zeta potential and isothermal calorimetric measurements. Calcium stearate lowered the viscosity of the dilute latex emulsion at low concentration suggesting a strong interaction with the latex particles due to a change in the hydrodynamic dimensions of the latex particles. The exothermic enthalpy change supported the assumption of a dissociative interaction. In contrast, both non-ionic polyethylene and organic triglyceride emulsion showed less pronounced enthalpy changes, indicating lower affinity for the latex particles. The reduction in viscosity showed, however, that at low lubricant concentrations there is an interaction between the latex particles and particularly the organic triglyceride emulsion. This suggests a selective adsorption of stabilizing agents and species from the lubricant emulsion which alters the hydrodynamic radius of the latex particles. The effects of the colloidal interactions on the morphology of the latex films monitored by Atomic Force Microscopy (AFM) indicated that specific surface interaction occurring in aqueous media influenced the topography and the surface chemical heterogeneity of the latex films. Especially in the case of calcium stearate, it seems that the dissolved species arrange themselves around the latex particles inhibiting film formation. The organic triglyceride, on the other hand, showed a lower interaction potential in the aqueous phase and it had a different impact on the film formation.

양생조건 및 보수방법에 따른 폴리머시멘트모르타르의 강도 성상

In this paper, polymer-modified repair materials using polymer dispersions with six repair methods are prepared with various polymer-cement ratios, and tested for compressive and flexural strengths through each curing condition such as dry cure, water cure, and freezing and thawing cyclic action. And, the adhesive interface between the polymer-modified mortar and mortar substrate is observed by a scanning electron microscope. From the test results, the compressive and flexural strengths of cement mortar repaired by polymer-modified mortar are improved with a rise in the polymer-cement ratio regardless of the type of polymer and curing conditions. Such an improvement in the strengths of polymer-modified repair materials to ordinary cement mortar is explained by the high adhesion of polymer-modified mortar. Strength reduction of polymer-modified repair materials after freezing and thawing cyclic actions is recognized, but it is lower than that of unmodified mortar. Especially, cement mortar repaired by polymer-modified mortar with a St/BA emulsion has good strength properties compared with those of SBR latex and PA emulsion. Accordingly, it is judged that polymer-modified mortars with a St/BA emulsion are possible to use as repair materials to ordinary cement mortar and concrete.

Structure and Drug Release in a Crosslinked Poly(Ethylene Oxide) Hydrogel

Hydrogels are a continuously expanding class of pharmaceutical polymers designed for sustained or controlled drug release. The structure and intermolecular interactions in such systems define their macroscopic properties. The aim of this study was to investigate the mechanism of swelling, drug impregnation, and drug release from poly(ethylene oxide) (PEO) gel crosslinked by urethane bonds. A combination of SAXS/WAXS/SANS techniques enabled us to determine the phase transition between lamellar and extended gel network, and to apply different descriptions of crystallinity, based on lamellar and crystal lattice structures. It is shown that even low (1-7% w/w) loading of model drugs acetaminophen and caffeine, produced significant disorder in the polymer matrix. This effect was particularly pronounced for acetaminophen due to its specific ability to form complexes with PEO. The drug-release profiles were analyzed using a general cubic equation, proposed for this work, which allowed us to determine the gel hydration velocity. The results indicate that the release profiles correlate inversely with the polymer crystallinity.

Advances in Emulsion Polymerization and Latex Technology

Advances in Emulsion Polymerization and Latex Technology

Painting and Printing Living Bacteria: Engineering Nanoporous Biocatalytic Coatings to Preserve Microbial Viability and Intensify Reactivity

Latex biocatalytic coatings containing approximately 50% by volume of microorganisms stabilize, concentrate and preserve cell viability on surfaces at ambient temperature. Coatings can be formed on a variety of surfaces, delaminated to generate stand-alone membranes or formulated as reactive inks for piezoelectric deposition of viable microbes. As the latex emulsion dries, cell preservation by partial desiccation occurs simultaneously with the formation of pores and adhesion to the substrate. The result is living cells permanently entrapped, surrounded by nanopores generated by partially coalesced polymer particles. Nanoporosity is essential for preserving microbial viability and coating reactivity. Cryo-SEM methods have been developed to visualize hydrated coating microstructure, confocal microscopy and dispersible coating methods have been developed to quantify the activity of the entrapped cells, and FTIR methods are being developed to determine the structure of vitrified biomolecules within and surrounding the cells in dry coatings. Coating microstructure, stability and reactivity are investigated using small patch or strip coatings where bacteria are concentrated 102- to 103-fold in 5-75 microm thick layers with pores formed by carbohydrate porogens. The carbohydrate porogens also function as osmoprotectants and are postulated to preserve microbial viability by formation of glasses inside the microbes during coat drying; however, the molecular mechanism of cell preservation by latex coatings is not known. Emerging applications include coatings for multistep oxidations, photoreactive coatings, stabilization of hyperthermophiles, environmental biosensors, microbial fuel cells, as reaction zones in microfluidic devices, or as very high intensity (>100 g.L-1 coating volume.h-1) industrial or environmental biocatalysts. We anticipate expanded use of nanoporous adhesive coatings for prokaryotic and eukaryotic cell preservation at ambient temperature and the design of highly reactive "living" paints and inks.

Association between a sodium salt of a linear dodecylbenzene sulphonate and a non-ionic fatty alcohol ethoxylate surfactant during film formation of styrene/butadiene latex

The influence of a linear anionic dodecylbenzene sulphonate (SDBS) and a non-ionic fatty alcohol ethoxylate (AE) surfactant on the compatibility and surface morphology of a medium carboxylated styrene/butadiene latex film was established. The latex films were prepared onto a mica substrate and annealed at 80 °C for 30 min. The AFM topography and phase contrast images enabled the localization of the surfactants on the latex films. The roughness parameters calculated for the captured images were utilized in order to identify the surface characteristics and changes caused by film ageing and addition of different surfactants. Both surfactants, but especially SDBS, increased the contrast between the latex particles. Addition of a blend of AE and SDBS surfactants to the latex emulsion resulted in the formation of hydrophobic nano-sized aggregates located at latex particle–particle boundaries in the films. The formation of the aggregates is ascribed to the association between the anionic and non-ionic surfactants. The segregated anionic surfactant was randomly distributed on-top of the latex films, whereas the surfactant blend showed a highly ordered, branched texture.

Study by isothermal calorimetry and electrophoresis of the interaction between latices and cellulose derivatives

The influence of the latex surface chemistry on the association of latices with different cellulose derivatives has been investigated by means of isothermal calorimetry and electrophoresis. The chemistries of three grades of coating latices differed with regard to the type and amount of vinylic monomer and the level of carboxylation. In addition, a styrene/butadiene latex substantially free from surfactant was used to establish the influence of physically pre-adsorbed surfactants on the association with the cellulose derivatives sodium carboxymethylcellulose (NaCMC), hydroxyethylcellulose (HEC) and ethyl(hydroxyethyl)cellulose (EHEC). The results show that the latex chemistry, in terms of hydrophilic character originating from carboxylic acid groups, significantly affects the adsorption of the non-ionic HEC and EHEC. A higher degree of carboxylation or a more polar latex, such as vinyl acetate/acrylate, reduces the association with non-ionic cellulose derivatives. The addition of anionic sodium dodecylbenzene sulphonate or non-ionic fatty alcohol ethoxylate surfactants to the surfactant-free styrene/butadiene latex emulsion did not significantly change the association behaviour with EHEC, although it was evident that, for example, a sodium dodecyl sulphonate type of surfactant participated significantly in the adsorption process. Even if the surface polarity of the latex governs the association characteristics at the interface, the solubility properties of the cellulose derivatives must be considered, meaning that the hydrophobic character plays an important role in the associative interaction between the latex and cellulose derivatives in aqueous media.