Particle size control in dispersion polymerization of polystyrene

1985 ◽  
Vol 63 (1) ◽  
pp. 209-216 ◽  
Author(s):  
Kar P. Lok ◽  
Christopher K. Ober
Keyword(s):  
Particle Size ◽  
Dispersion Polymerization ◽  
Homogeneous Solution ◽  
Size Control ◽  
Polymer Particle ◽  
Single Step ◽  
Spherical Particles ◽  
Polymerization Process ◽  
Aggregation Behaviour ◽  
Direct Preparation

In a dispersion polymerization process, the reaction mixture starts out as a homogeneous solution and the resulting polymer precipitates as spherical particles, stabilized by a steric barrier of dissolved polymer. The final polymer particle size is determined by the inherent polymer aggregation behaviour under a given set of conditions. In the present study styrene polymerization was studied in various solvents using cellulosic derivatives as the steric stabilizer. Some of these solvents in certain combinations allowed the direct preparation of particles in the micron size and their size distribution appeared to be highly dependent on the monomer–solvent–initiator system. Investigations of these factors have suggested that monodisperse particles up to 12 μm can be prepared in a single step; studies of several systems are delineated.

Process R&D for Particle Size Control of Molybdenum Oxide

2016 ◽  
Author(s):  
Sujat Sen ◽  
Trevor Dzwiniel ◽  
Krzysztof Pupek ◽  
Gregory Krumdick ◽  
Peter Tkac ◽  
...  
Keyword(s):  
Particle Size ◽  
Molybdenum Oxide ◽  
Size Control ◽  
Particle Size Control

Study of 5-Fluorouracil Loaded Chitosan Nanoparticles for Treatment of Skin Cancer

2020 ◽  
Vol 14 (3) ◽  
pp. 210-224
Author(s):  
Gayatri Patel ◽  
Bindu K.N. Yadav
Keyword(s):  
Particle Size ◽  
Controlled Release ◽  
Skin Cancer ◽  
Basal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Basal Cell ◽  
Chitosan Nanoparticles ◽  
Entrapment Efficiency ◽  
Fractional Factorial ◽  
Spherical Particles

Background: The purpose of this study was to formulate, characterize and in-vitro cytotoxicity of 5-Fluorouracil loaded controlled release nanoparticles for the treatment of skin cancer. The patents on nanoparticles (US8414926B1), (US61654404A), (WO2007150075A3) etc. helped in the selection polymers and method for the preparation of nanoparticles. Methods: In the present study nanoparticles were prepared by simple ionic gelation method using various concentrations of chitosan and sodium tripolyphosphate (TPP). Several process and formulation parameters were screened and optimized using 25-2 fractional factorial design. The prepared nanoparticles were evaluated for particle size, shape, charge, entrapment efficiency, crosslinking mechanism and drug release study. Results: The optimized 5-Fluorouracil loaded nanoparticle were found with particle size of of 320±2.1 nm, entrapment efficiency of 85.12%± 1.1% and Zeta potential of 29mv±1mv. Scanning electron microscopy and dynamic light scattering technique revealed spherical particles with uniform size. The invitro release profile showed controlled release up to 24 hr. Further study was carried using A375 basal cell carcinoma cell-line to elucidate the mechanism of its cytotoxicity by MTT assay. Conclusion: These results demonstrate that the possibility of delivering 5-Fluorouracil to skin with enhanced encapsulation efficiency indicating effectiveness of the formulation for treatment of basal cell carcinoma type of skin cancer.

scholarly journals Fabrication and Particle Size Control of Oxide Nanoparticles by Gas Phase Reaction Assisted with DC Plasma

2007 ◽  
Vol 44 (6) ◽  
pp. 447-452 ◽  
Author(s):  
Akira Watanabe ◽  
Motoharu Fujii ◽  
Masayoshi Kawahara ◽  
Takehisa Fukui ◽  
Kiyoshi Nogi
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Size Control ◽  
Oxide Nanoparticles ◽  
Phase Reaction ◽  
Dc Plasma ◽  
Gas Phase Reaction ◽  
Particle Size Control

Au, @ZrO2 yolk–shell catalysts for CO oxidation: Study of particle size effect by ex-post size control of Au cores

2012 ◽  
Vol 289 ◽  
pp. 100-104 ◽  
Author(s):  
Robert Güttel ◽  
Michael Paul ◽  
Carolina Galeano ◽  
Ferdi Schüth
Keyword(s):  
Particle Size ◽  
Size Effect ◽  
Co Oxidation ◽  
Size Control ◽  
Particle Size Effect ◽  
Oxidation Study ◽  
Ex Post

A Parametric Numerical Study of Radiative Transfer in Thermotropic Materials

2013 ◽  
Author(s):  
Adam C. Gladen ◽  
Susan C. Mantell ◽  
Jane H. Davidson
Keyword(s):  
Particle Size ◽  
Radiative Transfer ◽  
Optical Thickness ◽  
Parametric Study ◽  
Volume Fraction ◽  
Numerical Study ◽  
Anisotropic Scattering ◽  
Index Of Refraction ◽  
Spherical Particles ◽  
Size Parameter

A thermotropic material is modeled as an absorbing, thin slab containing anisotropic scattering, monodisperse, spherical particles. Monte Carlo ray tracing is used to solve the governing equation of radiative transfer. Predicted results are validated by comparison to the measured normal-hemispherical reflectance and transmittance of samples with various volume fraction and relative index of refraction. A parametric study elucidates the effects of particle size parameter, scattering albedo, and optical thickness on the normal-hemispherical transmittance, reflectance, and absorptance. The results are interpreted for a thermotropic material used for overheat protection of a polymer solar absorber. For the preferred particle size parameter of 2, the optical thickness should be less than 0.3 to ensure high transmittance in the clear state. To significantly reduce the transmittance and increase the reflectance in the translucent state, the optical thickness should be greater than 2.5 and the scattering albedo should be greater than 0.995. For optical thickness greater than 5, the reflectance is asymptotic and any further reduction in transmittance is through increased absorptance. A case study is used to illustrate how the parametric study can be used to guide the design of thermotropic materials. Low molecular weighted polyethylene in poly(methyl methacrylate) is identified as a potential thermotropic material. For this material and a particle radius of 200 nm, it is determined that the volume fraction and thickness should equal 10% and 1 mm, respectively.

Particle Size Control in Batch Crystallization of Pyrazinamide on Different Scales

2016 ◽  
Vol 20 (12) ◽  
pp. 2100-2107 ◽  
Author(s):  
Zai-Qun Yu ◽  
Alvin Yeoh ◽  
Pui Shan Chow ◽  
Reginald B. H. Tan
Keyword(s):  
Particle Size ◽  
Size Control ◽  
Batch Crystallization ◽  
Particle Size Control

scholarly journals Formulation, characterization and evaluation of nanoparticles based dry powder insufflation containing terbutaline sulphate and itraconazole for the treatment of asthma

2020 ◽  
Vol 11 (1) ◽  
pp. 567-580
Author(s):  
Venugopalaiah Penabaka ◽  
Kumar B ◽  
Prasad N.B.L
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Bronchial Asthma ◽  
Spherical Particles ◽  
Dry Powder ◽  
Terbutaline Sulphate ◽  
Release Studies ◽  
Physical Mixing ◽  
Spray Dried

Many factors affect the pulmonary drug delivery and stability of the nanoparticles an acupuncture consisting of bronchial asthma. Present research envisages on the development of dry powder nanoparticles as insufflation a acupuncture consisting of bronchial asthma (allergy due to Aspergillus fumigatus) using physical mixing and spray drying. Different founding are prepared and characterized with suitable excipients like lactose and trehalose. The particle size distribution of nano milled and spray-dried particles of Terbutaline Sulphate and Itraconazole showed unimodal size distribution. The formulations prepared with trehalose as the carrier showed less Dv90, Dv50 and Dv10 values due to the fineness in the particles of trehalose when compared to lactose. The Dv50  and Dv10 values were in the range of mountains of 0.43-0.89 µm and 0.21–0.49 µm for all formulations, which shows the primary particle size in the nanometer scale. Smooth and nearly spherical particles were produced for spray-dried formulations when compared to milled formulations. Zeta potential comes across until be between +17±0.13 to +32±0.12, which explains the particles as moderately stable. MMAD values ranges from 3.19 µm to 4.78 µm for milled nanoparticles and 3.45 µm to 4.21 µm for spray-dried particles. Formulated nanoparticles exhibited good spreading properties, which will allow all the particles to deposition palmy profusion territories consisting of the lung. In-vitro drug release studies explains that spray-dried formulations of Terbutaline sulpahte and Itraconazole using lactose as excipients released the drug upto 98.9% and 99.1% in 180mts.

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