Average Particle Size Of Latex Research Articles

Preparation and characterization of modified self-crosslinking fluorocarbon acrylate latex

The modified self-crosslinking fluorocarbon acrylate (MSFA) latex has been successfully synthesized via semi-continuous seeded emulsion polymerization. Methyl methylacrylate (MMA), butyl acrylate (BA), dodecafluoroheptyl methacrylate (DFMA), and hydroxypropyl methacrylate (HPMA) were chosen as main monomers, vinyl triethoxysilane (VTES), and benzyl methacrylate (BZMA) served as functional monomers. Latex was emulsified by mixed emulsifier containing nonionic surfactant alcohol ether glycoside (AEG1000) and anionic surfactant fatty alcohol polyoxyethylene ether sulfate (AES), and the reaction process was initiated by potassium persulfate (KPS). The optimal conditions were studied and obtained. The results indicated that the monomer conversion was up to 99.36%, and the coagulation was lowered to 0.60% under the optimal conditions. At the same time, the outward appearance of resultant latex presented blue white which confirmed the latex was a successful preparation. The latex was tested through Fourier-transform infrared spectroscopy (FTIR). The mechanical stability and chemical stability of latex were measured. Thermogravimeter (TGA) results demonstrated that the introduction of functional monomers has extensively augmented the thermal stability of prepared film. The glass transform temperature (Tg) was detected by differential scanning calorimetry (DSC) and the water resistance of film was evaluated through water contact angle (WCA). The average particle size of latex was 62.99 nm and PDI was 0.069.

Synthesis, characterization and fluorescence performance of a waterborne polyurethane-based polymeric dye

A novel anionic waterborne polyurethane-based fluorescent dye WPU-DV26 was synthesized by incorporating the molecular structure of disperse violet 26 (DV26) into the polyurethane chain. The structure of WPU-DV26 was confirmed by means of Fourier transform infrared spectroscopy and UV–vis absorption analysis. Comparing to the UV–vis spectrum of DV26, WPU-DV26 showed a hypsochromic shift from the absorption maxima of 518, 558, 609nm to 510, 548, 586nm, respectively. WPU-DV26 can form stable latex in water. The number average molecular weight and its distribution index, and average latex particle size for WPU-DV26 were determinedto be 2.33×104, 1.36 and 80nm, respectively. The improved thermal stability of WPU-DV26 can be attributed to the embedded anthraquinone unit of DV26. It was found that both the intensity and stability of the fluorescence of WPU-DV26 latex were improved significantly compared with those of DV26.

Atomic Force Microscopy Characterization of Latex Nanoparticles Synthesized by Slow Drying Process of Nano-Emulsion Polymerization

The nano-emulsion polymerization method was used to synthesize the latex nanoparticles. Two set of samples are prepared by fast drying and slow drying process. For each process they have a two different amount of monomer. The monomer consists of butyl methacrylate (BMA), butyl acrylate (BA), and methacrylic acid (MAA). The average particle size of latex by fast drying process is 31.94nm for low amount of monomer and 19.59nm for high amount of monomer. By slow drying process the average particle size of latex nanoparticles for low and high amount of monomer are 26nm and 8.62nm respectively. All the samples that were prepared are characterized by Atomic Force Microscopy (AFM). We have found that the butyl methacrylate (BMA) content in between 6g and 10g has sensitively effect to the synthesization of nano-polymer for the both method of fast drying process and slow drying process of nano-emulsion polymerization method.

Preparation of Styrene and Butyl Acrylate Emulsion with High Solid Content in the Presence of a Polymerizable Emulsifier

An emulsifier-free emulsion was synthesized via the preemulsified emulsion polymerization, with styrene (St), butyl acrylate(BA), and ammonium allyloxtmethylate nonylphenol ethoxylates sulfate (DNS-86) as the polymerizable emulsifier. The influences of the reaction temperature and time, DNS-86 amount on the emulsion polymerization were investigated, then the most suitable polymerizing conditions were obtained, the semi-continuous method was used, T=80°, t = 5 h, the dosage of DNS-86 was 2% of total monomers mass. The analysis of the profiles of IR, NMR, and Laser particle size demonstrated that the copolymerization occurred between St, BA and DNS-86 to generate P(St-BA-DNS-86) successfully, and hydrophilic sulfonic groups containing the copolymer were conducive to emulsion stability. Besides, the influences of the dosages of DNS-86 on the latex solid content and average particle size were discussed. The result showed that with the increase of DNS-86 amount, the latex solid content increased and average particle size of latex reduced, e.g., at the 2% mass amount of DNS-86 52.50% of the latex solid content, 78 nm of average diameter, 0.0379 of particle size distribution. Latex of high solids of up to 62.1% has been obtained with 5% DNS-86. The results of TEM showed that the copolymer emulsion with smaller particle size and uniform distribution could be obtained by using polymerizable emulsifier DNS-86.

Nanometre fluorinated acrylate latex prepared with gemini surfactant

The nanometre fluorinated acrylate latex was prepared via semi-continuous seeded emulsion polymerisation of butyl acrylate, methyl methacrylate and hexafluorobutyl acrylate in water phase when gemini surfactant and 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride are used to be emulsifier and initiator, respectively. The resultant latex is characterised by Fourier transform infrared (FTIR) spectrometry, contact angle measurements, dynamic light scattering and differential scanning calorimetry (DSC). FTIR spectrum identifies the formation of terpolymer. DSC confirms that the latex is a kind of random terpolymer and the consistency among the chain segment is fairly good. The average particle size of latex is decreased with the increase of the amount of gemini surfactant. The particle size of resultant latex is 22.4 nm and is further confirmed by transmission electron microscope when the amount of gemini surfactant is 3%. However, the viscosity of latex is increased with the increase of the amount of gemini surfactant. In comparison with the nanometre fluorinated acrylate latex, the hydrophobic property of the resultant latex is improved.

Synthesis and characterization of a novel waterborne stilbene-based polyurethane fluorescent brightener

Abstract A novel waterborne stilbene-based polyurethane fluorescent brightener dispersion WPU-VBL was synthesized by incorporating chemically disodium 4,4′-bis[(4-anilino-6-hydroxyethylamino-1,3,5-triazin-2-yl)amino]stilbene-2,2′-disulphonate (VBL) into the polyurethane chain using isophorone diisocyanate, poly(propylene glycol) and 2,2-dimethylol propionic acid. The structure of WPU-VBL was confirmed by means of Fourier transform infrared spectroscopy. The UV–vis absorption analysis showed a hypsochromic shift of 16 nm when VBL was blocked into polyurethane chain. Number average molecular weight of 2.1 × 10 4 , molecular weight distribution of 2.1 and average latex particle size of about 70 nm for WPU-VBL were determined based on the analysis of gel permeation chromatography and laser particle size analyzer. It was found that the fluorescence intensity of WPU-VBL was prominently enhanced because of the micro-circumstance of VBL and the fluorescence of WPU-VBL was very stable.

Studies on the Pseudo Ternary Phase Diagrams of Micro-emulsion Systems and Micro-emulsion Polymerization of H-PDMS/MMA/ n-BA

The pseudo phase diagrams of the systems of (OP-10/SDS)/butanediol-hydrogen-contained polymethylsiloxane (H-PDMS)/methyl methacrylate (MMA)/n-butyl acrylate (n-BA)–water, with different amounts of H-PDMS, were drawn. PDMS/P (MMA-BA) nano-composite latex particles were prepared by micro-emulsion polymerization, and the initiator was dripped into the micro-emulsion. The experiment results showed that when the amount of H-PDMS was in the range of 2.5∼3.5%, the area of O/W of micro-emulsion in pseudo phase diagram was relatively large, while when the amount of H-PDMS was less than or greater than 2.5∼3.5 %, the area of O/W of micro-emulsion was relatively small. In the micro-emulsion polymerization process, the average size of latex particles was dominated by the amount of initiator and the polymerization temperature. The experiment results also indicated that the size of the PDMS/P (MMA-BA) nano-composite latex particles is in the range of 26–65 nm, with the concentration of the initiator in the range of 0.6 × 10–2-1.46×10−2mol/L, at temperature 60–65°C.

The Effect of Weight Fraction of H-PDMS on the Latex Membrane and the Stability of Composite Emulsion of H-PDMS/Acrylate

High hydrogen-containing polymethylsiloxane(H-PDMS)/polyacrylate composite emulsion was synthesized by a drop-adding method for monomer emulsion. The effects of weight fraction of H-PDMS on the stability of composite emulsion, water resistance and heat-aging resistance of the latex membrane have been investigated. The TEM demonstrated that latex particles are a core-shell structure. By analyzing the spectrums of FTIR and 1H-NMR, it can be indicated that H-PDMS had reacted with acrylate monomer resulting chemical bond formation. The core-shell structure and chemical bond play an important role to restrain phase separation of composite emulsion and enhance the stability of the emulsion. By analyzing the surface tension, apparent viscosity and morphological structure, the results showed that the stable composite emulsion system can be obtained in which the average latex particle size was smaller than 90 nm when weight fraction of H-PDMS is below 16% (based on the weight of acrylate monomer), the stable emulsion system can be obtained in which the average latex particle size becomes larger than 90 nm when the weight fraction of H-PDMS is above 20% of the acrylate monomer. The DSC demonstrated that the Tg of pure polyacrylate is 49°C, and there is only one Tg (35°C) when the weight fraction of H-PDMS is 13%, but there are two Tg (15°C and 25°C) when the weight fraction of H-PDMS is 16%. In addition, the water resistance and heat-aging resistance of composite latex membrane enhanced gradually with the increase of amount of H-PDMS.

The Effect of Oxygen on the Kinetics and Particle Size Distribution in Vinyl Chloride Emulsion Polymerization

A comprehensive mathematical model is developed to quantify the effect of the oxygen concentration on the polymerization rate and particle size distribution in an unseeded vinyl chloride batch emulsion polymerization reactor. Particle formation is assumed to proceed by both the homogeneous and micellar nucleation mechanisms. Dynamic species mass balances are derived to follow the evolution of the polymerization rate and particle size distribution (PSD) in the batch reactor. It is shown that, at low initial oxygen concentrations, the polymerization rate increases with the oxygen concentration. On the other hand, the average latex particle size exhibits a U-shaped behavior with respect to the initial oxygen concentration. The experimental observations on the polymerization rate and the average particle size are explained by the combined role of oxygen as an inhibitor and a radical generator through the formation and subsequent decomposition of vinyl polyperoxides. The predictive capabilities of the present model are demonstrated through the successful simulation of experimental data on monomer conversion and PSD obtained from an industrial pilot-plant batch PVC reactor operated with various initial oxygen and initiator concentrations.

Effects of ionizable groups on the adsorption of surfactants onto latex particle surfaces

Soap titration of polymeric latices can be used both for the determination of an average latex particle size and as a method for investigating the adsorption of surfactants onto hydrophobic surfaces. This investigation has studied the adsorption of anionic and nonionic surfactants onto polystyrene latex particles in order to develop an understanding of the relationship between surfactant structural characteristics (chain length and end-group) and the area occupied by an adsorbed molecule. As expected the area occupied by a surfactant molecule increased as the ethylene oxide chain length increased for a series of octaphenoxy ethoxylate nonionic surfactants. The results also indicated that in addition to structural factors the adsorption area of a surfactant molecule is also dependent upon the surface charges present on the particle surface. For the nonionic surfactants studied the adsorption area per molecule increased as the number of charges chemically attached to the particle surface increased (increasing surface polarity). For sodium dodecyl sulfate, however, just the opposite trend was observed. The increase in the amount of sodium dodecyl sulfate adsorbed with increasing surface charge may be due to a more extended configuration for the adsorbed surfactant molecules which gives rise to more surfactant—surfactant interactions. These surface charges, which arise from the initiator, may vary widely from one latex to another depending upon the polymerization method and recipe and may be responsible for some of the scatter in previous soap titration results.

Chemistry and Structure of Natural Rubbers

Abstract Natural rubbers are synthesized in thousands of species covering most plant families; moreover, rubber has been obtained commercially from over a dozen of them. A later report has suggested that polyisoprene formation is limited to dicotyledonous angiosperms. In recent years there has been renewed interest in developing alternative sources of natural rubber, different from Hevea brasiliensis. In particular there has been considerable development of guayule as a source of natural rubber. As a result there is a considerable body of recent results, using new techniques and extending older work concluded in the 1950's, which give new insight into the production of rubber in plants. This paper will mainly deal with guayule because it can ideally serve as a background for understanding the production of rubbers in other plants, including hevea. First, it is necessary to describe the physical nature of the rubber from guayule and where in the plant it is formed. Figure 1 shows a cross-section of a stem of guayule. The individual cells (parenchyma cells) are the site of rubber manufacture. The rubber can finally be seen as the small latex droplets inside a single cell (Figure 2). Thus the study of the natural rubber in guayule involves the isolation of the latex particles from the cell. It is extremely easy to separate an industrial rubber from other parts of the plant, including resin, by either laboratory or pilot plant methods. However, it is more difficult to get fresh latex in which no additional particle coagulation has occurred. The description of the average latex particle size and the distribution of sizes has been made and is needed to discuss the biosynthesis of rubber. It will not be discussed further. The question addressed in this paper is the chemical structure of the rubber in the plants—the micro-structure of the rubber, the molecular weight distribution, and the branching or gel content. Guayule natural rubber has the remarkable feature of containing no gel when taken directly from a fresh plant and carefully handled in the laboratory. Even the material from the pilot plant extraction process contains only 1–3 per cent gel. This paper describes extensively the chemical structure of natural rubber extracted from fresh guayule plants. Less extensive measurements on chicle, gutta-percha, and castilla elastica are also reported. Finally, all of the data are analyzed to determine if a model of rubber production can be formulated to encompass all of the above plants. Earlier, a model was proposed for guayule only. In this model the polyisoprene chain is polymerized on the polymerase enzyme site by recurring attachment and intermittent polymerization until the rubber droplet (containing a single polymer chain) can no longer be stabilized or further polymerized by the enzyme.

Preparation of monodisperse polystyrene latices

A series of monodisperse polystyrene latices was prepared by using the direct and the seeding emulsion polymerization methods. The recipes for their preparation are given in full detail. Best results were obtained when using Aerosol MA (a surfactant of the sulfosuccinate series) as the emulsifier. The particle size distributions were evaluated from electron microscopic data. The average size of latex particles ranged from 200 to 950 mμ. The polydispersity ratios being very near unity and modal frequencies about 95% indicate a very high monodispersity of latex preparations. The reproducibility of the particle size distribution parameters was remarkably good. Significant deviation from theSmith-Ewart mechanism was found. A possible mechanism of the emulsifier action in the formation of monodisperse latices is postulated.