Author: Vijayakumar S. RamachandraRao
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 3
Book Description
CO2-induced Phase Separation in Multi-component Polymer Systems Studied by Fluorescence Spectroscopy
Author: Vijayakumar S. RamachandraRao
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 3
Book Description
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 3
Book Description
Phase Separation Kinetics in Reactive and Non-reactive Multi-component Polymer Systems
Author: Rahul Saxena
Publisher:
ISBN:
Category :
Languages : en
Pages : 390
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 390
Book Description
Phase Relations in Multicomponent Polymer Systems
Author: R. J. Roe
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
Book Description
In this project a number of polymer blend systems were studied to find the thermodynamic factors controlling the compatibility, such as the temperature, concentration, molecular weight and the copolymer composition, etc. Topics investigated include: The polymer-polymer interaction parameter between polystyrene and polybutadiene was determined, and the applicability of mean field theories (Flory-Huggins theory and the equation-of-state theory) to the polymer miscibility was ascertained. The feasibility of determining the thickness of interfaces between dissimilar polymers by means of small-angle X-ray scattering was critically examined. The occurrence of the order-disorder transition in block copolymer system were investigated. Light scattering and small-angle X-ray scattering were utilized to study the phase transition and phase separation behavior of mixtures of a homopolymer and a block copolymer, and this led to the construction of phase diagrams which exhibit many new features not found with other types of polymer blends. Deuteration of polystyrene was found not to influence its miscibility with polybutadiene. The effectiveness of a random or block copolymer as a compatibilizer of homopolymer blends was investigated. The effect of molecular weight polydipersity on the cloud point curves of polymeric blends was investigated.
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
Book Description
In this project a number of polymer blend systems were studied to find the thermodynamic factors controlling the compatibility, such as the temperature, concentration, molecular weight and the copolymer composition, etc. Topics investigated include: The polymer-polymer interaction parameter between polystyrene and polybutadiene was determined, and the applicability of mean field theories (Flory-Huggins theory and the equation-of-state theory) to the polymer miscibility was ascertained. The feasibility of determining the thickness of interfaces between dissimilar polymers by means of small-angle X-ray scattering was critically examined. The occurrence of the order-disorder transition in block copolymer system were investigated. Light scattering and small-angle X-ray scattering were utilized to study the phase transition and phase separation behavior of mixtures of a homopolymer and a block copolymer, and this led to the construction of phase diagrams which exhibit many new features not found with other types of polymer blends. Deuteration of polystyrene was found not to influence its miscibility with polybutadiene. The effectiveness of a random or block copolymer as a compatibilizer of homopolymer blends was investigated. The effect of molecular weight polydipersity on the cloud point curves of polymeric blends was investigated.
Multicomponent Diffusion and Phase Separation in Asymmetric Ternary Polymer Systems
Author: Abdulrahman A. Alfarraj
Publisher: ProQuest
ISBN: 9780549286608
Category : Chemical and biological engineering
Languages : en
Pages : 214
Book Description
Publisher: ProQuest
ISBN: 9780549286608
Category : Chemical and biological engineering
Languages : en
Pages : 214
Book Description
Phase Segregation in Multi-component Polymer Systems
Author: Sibichen Joseph
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The phase segregation investigated in this work is the migration of dispersed particles or droplets to preferred locations in a polymer melt. An understanding of this area can lead to polymer processing directed at de-mixing polymer blends for recycling purposes and at the formation of multi-layer structures of polymers without co-extrusion. Although it is now recognized that viscosity ratio is an important factor in achieving phase segregation in polymer melts, non-Newtonian and elastic effects complicate the situation. This thesis is an investigation of these effects. The thesis centers on testing four hypotheses: (1) phase segregation does not take place in a Newtonian fluid; (2) in a shear thinning fluid having negligible elasticity, migration of the dispersed phase will be towards the high shear rate region of the flow; (3) in a significantly elastic fluid having negligible variation of viscosity with shear rate, migration of the dispersed phase will be towards the low shear rate region of the flow and; (4) in a fluid which is both shear thinning and elastic, the direction and extent of migration will depend upon the relative "strength" of the shear thinning and elastic effects. The validity of these hypotheses was tested using three types of experiments (all conducted at 250°C): melting and shearing a rod of the polymer containing the particles at well defined positions in a Couette apparatus (Couette-Rod Experiments); shearing of a polymer melt containing dispersed phase, which was extruded into the Couette apparatus (Couette-Extrusion Experiments) and; flow of a polymer melt containing the dispersed particles in a very long tube (Tube Experiments). Experiments were performed using both rigid particles (Glass beads) and deformable droplets (Polyamide 612 (PA612) droplets) as the dispersed phase. Polycarbonate (PC) was used as the Newtonian fluid for testing the first hypothesis. Poly(acrylonitrile butadiene styrene) copolymer (ABS) melt served as the test fluid in validating the remaining three hypotheses due to its particular dependence of rheological characteristics upon the shear rate. (Abstract shortened by UMI.).
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The phase segregation investigated in this work is the migration of dispersed particles or droplets to preferred locations in a polymer melt. An understanding of this area can lead to polymer processing directed at de-mixing polymer blends for recycling purposes and at the formation of multi-layer structures of polymers without co-extrusion. Although it is now recognized that viscosity ratio is an important factor in achieving phase segregation in polymer melts, non-Newtonian and elastic effects complicate the situation. This thesis is an investigation of these effects. The thesis centers on testing four hypotheses: (1) phase segregation does not take place in a Newtonian fluid; (2) in a shear thinning fluid having negligible elasticity, migration of the dispersed phase will be towards the high shear rate region of the flow; (3) in a significantly elastic fluid having negligible variation of viscosity with shear rate, migration of the dispersed phase will be towards the low shear rate region of the flow and; (4) in a fluid which is both shear thinning and elastic, the direction and extent of migration will depend upon the relative "strength" of the shear thinning and elastic effects. The validity of these hypotheses was tested using three types of experiments (all conducted at 250°C): melting and shearing a rod of the polymer containing the particles at well defined positions in a Couette apparatus (Couette-Rod Experiments); shearing of a polymer melt containing dispersed phase, which was extruded into the Couette apparatus (Couette-Extrusion Experiments) and; flow of a polymer melt containing the dispersed particles in a very long tube (Tube Experiments). Experiments were performed using both rigid particles (Glass beads) and deformable droplets (Polyamide 612 (PA612) droplets) as the dispersed phase. Polycarbonate (PC) was used as the Newtonian fluid for testing the first hypothesis. Poly(acrylonitrile butadiene styrene) copolymer (ABS) melt served as the test fluid in validating the remaining three hypotheses due to its particular dependence of rheological characteristics upon the shear rate. (Abstract shortened by UMI.).
Phase Separation in Polymer Blends and Block Copolymers Induced by Differential Dilation with CO2
Author: James J. Watkins
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 3
Book Description
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 3
Book Description
Publications of the National Institute of Standards and Technology ... Catalog
Author: National Institute of Standards and Technology (U.S.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 1162
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 1162
Book Description
American Doctoral Dissertations
Author:
Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 776
Book Description
Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 776
Book Description
Amorphous Solid Dispersions
Author: Navnit Shah
Publisher: Springer
ISBN: 1493915983
Category : Medical
Languages : en
Pages : 702
Book Description
This volume offers a comprehensive guide on the theory and practice of amorphous solid dispersions (ASD) for handling challenges associated with poorly soluble drugs. In twenty-three inclusive chapters, the book examines thermodynamics and kinetics of the amorphous state and amorphous solid dispersions, ASD technologies, excipients for stabilizing amorphous solid dispersions such as polymers, and ASD manufacturing technologies, including spray drying, hot melt extrusion, fluid bed layering and solvent-controlled micro-precipitation technology (MBP). Each technology is illustrated by specific case studies. In addition, dedicated sections cover analytical tools and technologies for characterization of amorphous solid dispersions, the prediction of long-term stability, and the development of suitable dissolution methods and regulatory aspects. The book also highlights future technologies on the horizon, such as supercritical fluid processing, mesoporous silica, KinetiSol®, and the use of non-salt-forming organic acids and amino acids for the stabilization of amorphous systems. Amorphous Solid Dispersions: Theory and Practice is a valuable reference to pharmaceutical scientists interested in developing bioavailable and therapeutically effective formulations of poorly soluble molecules in order to advance these technologies and develop better medicines for the future.
Publisher: Springer
ISBN: 1493915983
Category : Medical
Languages : en
Pages : 702
Book Description
This volume offers a comprehensive guide on the theory and practice of amorphous solid dispersions (ASD) for handling challenges associated with poorly soluble drugs. In twenty-three inclusive chapters, the book examines thermodynamics and kinetics of the amorphous state and amorphous solid dispersions, ASD technologies, excipients for stabilizing amorphous solid dispersions such as polymers, and ASD manufacturing technologies, including spray drying, hot melt extrusion, fluid bed layering and solvent-controlled micro-precipitation technology (MBP). Each technology is illustrated by specific case studies. In addition, dedicated sections cover analytical tools and technologies for characterization of amorphous solid dispersions, the prediction of long-term stability, and the development of suitable dissolution methods and regulatory aspects. The book also highlights future technologies on the horizon, such as supercritical fluid processing, mesoporous silica, KinetiSol®, and the use of non-salt-forming organic acids and amino acids for the stabilization of amorphous systems. Amorphous Solid Dispersions: Theory and Practice is a valuable reference to pharmaceutical scientists interested in developing bioavailable and therapeutically effective formulations of poorly soluble molecules in order to advance these technologies and develop better medicines for the future.
Dissertation Abstracts International
Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 882
Book Description
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 882
Book Description