Miniemulsions of Vinyl Stearate. II. Light-Scattering Studies During the Polymerization

1989 ◽  
Vol 42 (12) ◽  
pp. 2085 ◽  
Author(s):  
E Elbing ◽  
AG Parts ◽  
CJ Lyons ◽  
BAW Coller ◽  
IR Wilson
Keyword(s):  
Particle Size ◽  
Light Scattering ◽  
Aqueous Medium ◽  
Particle Collision ◽  
Collision Theory ◽  
Polymer Particles ◽  
Final Particle ◽  
Emulsion Droplets

The course of the polymerization of vinyl stearate has been followed by dilatometry and by light scattering. Kinetically stable and visually clear or at most opalescent 'miniemulsions' were used to minimize the scattering (otherwise large) by emulsion droplets. Light-scattering results demonstrate that the final particle size of the latexes may be greater or less than that of the emulsion droplets in the starting miniemulsion. This suggests that polymer particles are nucleated from the aqueous (micelle-containing) phase, and grow by transport of vinyl stearate monomer through the aqueous medium from the emulsion droplets to feed polymerization in the particles. Thus the droplets gradually decrease in size and disappear when all the monomer has been taken up by absorption into micelles or into growing particles. A previously proposed droplet-particle collision theory does not appear to be necessary.

scholarly journals Impact of Sample Concentration on the Determination of Particle Size of Nano Polymer Particles and Nano Liposomes by Dynamic Light Scattering

2019 ◽  
Vol 35 (2) ◽  
Author(s):  
Tran Thi Hai Yen ◽  
Le Thi Huyen ◽  
Tran Hong Nhung ◽  
Le Thi Thu Trang ◽  
Pham Thi Minh Hue
Keyword(s):  
Particle Size ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Count Rate ◽  
Drug Loading ◽  
Publishing House ◽  
Nano Particles ◽  
Size Analysis ◽  
Polymer Particles

Determination of particles size is important in pharmaceutical research and manufacturing of drug delivery system in nano scale. This study was carried out to evaluate particles size of nano polymer particles, composed of Eudragit RL 100, and nano liposomes, composed of hydrogenated soy phosphatidylcholine and cholesterol. Dynamic light scaterring was used to determine nano particles size. The results showed that, dilution ratio influenced differently on the determined nanoparticles.  Liposomal suspension, which was diluted to count rate less than 170 kcps, had statistically significant larger particle than that, which had greater count rate. Polymer particles, which were diluted to count rate less than 126 had statistically significant larger particles than that, which had greater count rate. Keywords Particle size, nano polymer particle, nano liposomes, dynamic light scattering (DLS). References [1] E.H.M. Sakho, E. Allahyari, O.S. Oluwafemi, S. Thomas, and N. Kalarikkal, Dynamic Light Scattering (DLS) in: Thermal and rheological measurement techniqus for nanometerials characterization, Elsevier, Europe 2017.[2] V.X. Minh, P.T.M. Hue, Applications of nanotechnology and liposomes in Pharmaceuticals and cosmetics, Medical publishing house, Hanoi, 2013 (in Vietnamese).[3] ISO 22412:2017, Particle size analysis - Dynamic light scattering (DLS).[4] J. Panchal, J. Kotarek, E. Marszal, and E.M. Topp, Analyzing Subvisible Particles in Protein Drug Products: a Comparison of Dynamic Light Scattering (DLS) and Resonant Mass Measurement (RMM), AAPS J., 16(3) (2014) 440–451. http://doi.org/ 10.1208/s12248-014-9579-6.[5] A. Chaudhury et al, Lyophilization of cholesterol-free PEGylated liposomes and its impact on drug loading by passive equilibration, Int. J. Pharm., 430(1–2) (2012) 167–175. https://doi.org/10.1016/j.ijpharm.2012.04.036.[6] T. Ishida, H. Harashima, and H. Kiwada, Liposome clearance, Biosci. Rep., 22(2) (2002) 197–224. https://doi.org/10.1023/A:1020134521778.    

Analysis of platelet aggregation using particle collision theory

1983 ◽  
Vol 245 (6) ◽  
pp. R776-R784
Author(s):  
T. M. Davis ◽  
E. Bown
Keyword(s):  
Particle Size ◽  
Platelet Aggregation ◽  
Inflection Point ◽  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Quantitative Information ◽  
Particle Collision ◽  
Collision Theory ◽  
Response Curves

The aggregometer monitors changes in light transmission through stirred suspensions of aggregation platelets. Arbitrary measurements from aggregometer recorder tracings have been used to investigate platelet aggregation without regard to mechanisms involved. To determine the applicability of particle collision theory to assessment of in vitro platelet sensitivity to proaggregating agents, platelet-rich plasma (PRP) from five volunteers was used to obtain recorder tracings after addition of ADP in five doses (0.4-4.0 mumol/l PRP) to aliquots of PRP stirred and incubated in an aggregometer. Using the equation describing light transmission through particulate suspensions, particle collision theory, and s (the probability of particle union after collision), a subject- and dose-independent relationship between aggregation rate (dn/dt) and particle number (n) at the recorder tracing inflection point was found (dn/dt = -k X s X n1.56, where k is a constant dependent on particle size and speed and on the proportion of unreactive particles). Determinations of mean particle size at the tracing inflection point indicated that k was also dose independent. Dose-response curves of ADP added vs. s could therefore be constructed. This methodology provides conveniently obtainable quantitative information concerning in vitro platelet “stickiness.”

scholarly journals Influence of size polydispersity on magnetic field tunable structures in magnetic nanofluids containing superparamagnetic nanoparticles.

2021 ◽  
Author(s):  
Dillip Kumar Mohapatra ◽  
Philip James Camp ◽  
John Philip
Keyword(s):  
Magnetic Field ◽  
Particle Size ◽  
Light Scattering ◽  
Optical Microscopy ◽  
Brownian Dynamics ◽  
Phase Contrast ◽  
Superparamagnetic Nanoparticles ◽  
Magnetic Nanofluids ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations

We probe the influence of particle size polydispersity on field-induced structures and structural transitions in magnetic fluids (ferrofluids) using phase contrast optical microscopy, light scattering and Brownian dynamics simulations. Three...

scholarly journals A thermodynamic assessment of precipitation, growth, and control of MnS inclusion in U75V heavy rail steel

2021 ◽  
Vol 40 (1) ◽  
pp. 178-192
Author(s):  
Wen-Qiang Ren ◽  
Lu Wang ◽  
Zheng-Liang Xue ◽  
Cheng-Zhi Li ◽  
Hang-Yu Zhu ◽  
...  
Keyword(s):  
Particle Size ◽  
Rail Steel ◽  
Solidification Process ◽  
Segregation Ratio ◽  
Two Phase ◽  
Final Particle ◽  
Solid Liquid ◽  
And Control ◽  
Heavy Rail ◽  
Heavy Rail Steel

Abstract Thermodynamic analysis of the precipitation behavior, growth kinetic, and control mechanism of MnS inclusion in U75V heavy rail steel was conducted in this study. The results showed that solute element S had a much higher segregation ratio than that of Mn, and MnS would only precipitate in the solid–liquid (two-phase) regions at the late stage during the solidification process at the solid fraction of 0.9518. Increasing the cooling rate had no obvious influence on the precipitation time of MnS inclusion; however, its particle size would be decreased greatly. The results also suggested that increasing the concentration of Mn would lead to an earlier precipitation time of MnS, while it had little effect on the final particle size; as to S, it was found that increasing its concentration could not only make the precipitation time earlier but also make the particle size larger. Adding a certain amount of Ti additive could improve the mechanical properties of U75V heavy rail steel due to the formation of TiO x –MnS or MnS–TiS complex inclusions. The precipitation sequences of Ti3O5 → Ti2O3 → TiO2 → TiO → MnS → TiS for Ti treatment were determined based on the thermodynamic calculation.

scholarly journals Grinding Kinetics of Slag and Effect of Final Particle Size on the Compressive Strength of Alkali Activated Materials

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 714 ◽  
Author(s):  
Evangelos Petrakis ◽  
Vasiliki Karmali ◽  
Georgios Bartzas ◽  
Konstantinos Komnitsas
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Ageing Time ◽  
Reduction Rate ◽  
Curing Temperature ◽  
Alkali Activation ◽  
Final Particle ◽  
Alkali Activated

This study aims to model grinding of a Polish ferronickel slag and evaluate the particle size distributions (PSDs) of the products obtained after different grinding times. Then, selected products were alkali activated in order to investigate the effect of particle size on the compressive strength of the produced alkali activated materials (AAMs). Other parameters affecting alkali activation, i.e., temperature, curing, and ageing time were also examined. Among the different mathematical models used to simulate the particle size distribution, Rosin–Rammler (RR) was found to be the most suitable. When piecewise regression analysis was applied to experimental data it was found that the particle size distribution of the slag products exhibits multifractal character. In addition, grinding of slag exhibits non-first-order behavior and the reduction rate of each size is time dependent. The grinding rate and consequently the grinding efficiency increases when the particle size increases, but drops sharply near zero after prolonged grinding periods. Regarding alkali activation, it is deduced that among the parameters studied, particle size (and the respective specific surface area) of the raw slag product and curing temperature have the most noticeable impact on the compressive strength of the produced AAMs.

PLATELET AGGREGATION DOES NOT CONFORM TO SIMPLE PARTICLE COLLISION THEORY

1987 ◽  
Author(s):  
Moideen P Jamaluddin
Keyword(s):  
Platelet Aggregation ◽  
Rate Equation ◽  
Rate Constants ◽  
Kinetic Scheme ◽  
Order Type ◽  
Second Order ◽  
Particle Collision ◽  
Collision Theory ◽  
Rate Law ◽  
First Order

Platelet aggregation kinetics, according to the particle collision theory, generally assumed to apply, ought to conform to a second order type of rate law. But published data on the time-course of ADP-induced single platelet recruitment into aggregates were found not to do so and to lead to abnormal second order rate constants much larger than even their theoretical upper bounds. The data were, instead, found to fit a first order type of rate law rather well with rate constants in the range of 0.04 - 0.27 s-1. These results were confirmed in our laboratory employing gelfiltered calf platelets. Thus a mechanism much more complex than hithertofore recognized, is operative. The following kinetic scheme was formulated on the basis of information gleaned from the literature.where P is the nonaggregable, discoid platelet, A the agonist, P* an aggregable platelet form with membranous protrusions, and P** another aggregable platelet form with pseudopods. Taking into account the relative magnitudes of the k*s and assuming aggregation to be driven by hydrophobic interaction between complementary surfaces of P* and P** species, a rate equation was derived for aggregation. The kinetic scheme and the rate equation could account for the apparent first order rate law and other empirical observations in the literature.

Fabrication of convex lens-shaped polymer particles by tuning the interfacial interaction

2017 ◽  
Vol 1 (3) ◽  
pp. 507-511 ◽  
Author(s):  
Jiangping Xu ◽  
Yi Yang ◽  
Ke Wang ◽  
Yuqing Wu ◽  
Jintao Zhu
Keyword(s):  
Block Copolymers ◽  
Small Molecules ◽  
Interfacial Interaction ◽  
Polymer Particles ◽  
Emulsion Droplets ◽  
Convex Lens ◽  
Cylindrical Domains

With the addition of small molecules to emulsion droplets containing block copolymers, anisotropic convex lens-like particles with hexagonally stacked cylindrical domains can be readily achieved by using a single surfactant to create a neutral interface for both blocks.

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