Polymer Science Commons^™

Nucleation Initiated Spinodal Decomposition In A Polymerizing System, Thein Kyu, Jae Hyung Lee

College of Polymer Science and Polymer Engineering

Dynamics of phase separation in a polymerizing system, consisting of carboxyl terminated polybutadiene acrylonitrile/epoxy/methylene dianiline, was investigated by means of time-resolved light scattering. The initial length scale was found to decrease for some early periods of the reaction which has been explained in the context of nucleation initiated spinodal decomposition We have combined the Cahn-Hilliard kinetic equation and polymerization kinetics, and predicted the initial reduction of the length scale triggered by nucleation.

Non-Markovian Brownian Motion In A Viscoelastic Fluid, V. S. Volkov, Arkadii I. Leonov

College of Polymer Science and Polymer Engineering

A theory of non-Markovian translational Brownian motion in a Maxwell fluid is developed. A universal kinetic equation for the joint probability distribution of position, velocity, and acceleration of a Brownian particle is derived directly from the extended dynamic equations for the system. Unlike the extended Fokker-Planck equation which corresponds to Mori-Kubo generalized Langevin equation and provides only with calculations of one-time moments, the universal kinetic equation obtained gives complete statistical description of the process. In particular, an exact generalized Fokker-Planck equation in the velocity space valid for any time instant is derived for the free non-Markovian Brownian motion. It shows …

On The Importance Of Chain Reptation In Models Of Dissolution Of Glassy Polymers, Balaji Narasimhan, Nikolaos A. Peppas

Balaji Narasimhan

Polymer dissolution was described by chain reptation incorporated into penetrant transport. The penetrant concentration field was divided into three regimes which delineate three different transport processes. Solvent penetration through the polymer was modeled to occur as a consequence of a diffusional flux and an osmotic pressure contribution. Species momentum balances were written that coupled the polymer viscoelastic behavior with the transport mechanism. Transport in the second penetrant concentration regime was modeled to occur in a diffusion boundary layer adjacent to the rubbery-solvent interface, where a Smoluchowski type diffusion equation was obtained. The disentanglement rate of the polymer is given by …

Low-Valent Metal Complexes As Reductive Coupling Agents For Smoke Suppression In Poly(Vinyl Chloride), Panagiotis Ioannou Kourtesis

Dissertations, Theses, and Masters Projects

No abstract provided.

Synthesis And Characterization Of Boron-Containing Polymeric Materials For Neutron Shielding Applications, Michael B. Glasgow

Dissertations, Theses, and Masters Projects

The development of boron-containing polymeric materials for neutron shielding applications was undertaken. Three types of materials were characterized for physical and thermal properties: boron powder-filled epoxy composites, carborane polyamides having boron chemically bonded into the polymer, and boron-loaded polyimide thin films. Addition of amorphous submicron boron powder did not affect significantly the thermal performance of the epoxy. The 17% boron loading produced a 26% increase in compressive failure strength and a 68% increase in the compressive modulus. 0.125 inch thick specimens containing 17% boron absorbed 92% of incident neutrons from a 5-Curie Pu/Be source compared with {dollar}<{dollar}1% for the neat epoxy. Dispersion of the boron in the epoxy was improved with the addition of larger size crystalline boron powders. Carborane polyamides containing up to 35% boron were thermally stable up to 400{dollar}\sp\circ{dollar}C in air. The polymers had hydrogen/boron ratios from 2.0 to 3.8 and were soluble in several organic solvents. Polymer solutions were processed into clear, colored thin films. Boron-filled polyamic acid solutions of a PMDA-ODA polyimide containing up to 10% boron were processed into thin films. Neutron absorption of the opaque films measured in a 5-Curie Pu/Be neutron source was linear with boron concentration and film thickness. The fraction of neutrons absorbed varied linearly with boron concentration and film thickness. The applicability of boron-containing materials to the aerospace, nuclear power and accelerator industries was investigated.

Dynamic Viscoelastic Properties Of Poly(Ethylene-Propylene) Diblock Copolymer In The Melt State And Solutions, William Macknight, K. Sakurai, D.J. Lohse, D.N. Schulz, J.A. Sissano, W. Wedler, H. H. Winter

William MacKnight

No abstract provided.

Structure And Properties Of Polyelectrolyte-Surfactant Nonstoichiometric Complexes In Low-Polarity Solvents, William Macknight, Kirill N. Bakeev, Yang M. Shu, Alexander B. Zezin, Viktor A. Kabanov, Andrey V. Lezov, Alexander B. Mel'nikov, Igor P. Kolomiets, Evgenii I. Rjumtsev

William MacKnight

No abstract provided.

Ionomeric Blends Of Poly(Ethyl Acrylate-Co-4-Vinylpyridine) With Zinc-Neutralized Sulfonated Poly(Ethylene Terephthalate). 3. Effects Of Functionalization Level, William Macknight, C. W. Alice Ng

William MacKnight

No abstract provided.

Self-Assembled Complexes Of Synthetic Polypeptides And Oppositely Charged Low Molecular Weight Surfactants. Solid-State Properties, William Macknight, Ekaterina A. Ponomarenko, Alan J. Waddon, Kirill N. Bakeev, David A. Tirrell

William MacKnight

Ionomeric Blends Of Poly(Ethyl Acrylate-Co-4-Vinylpyridine) With Metal-Neutralized Sulfonated Poly(Ethylene Terephthalate). 4. Effects Of Counterions, William Macknight

William MacKnight

No abstract provided.

Blends Of Amorphous-Crystalline Block Copolymers With Amorphous Homopolymers. Morphological Studies By Electron Microscopy And Small Angle Scattering, William Macknight, Kazuo Sakurai, David J. Lohse, Donald N. Schulz, J.A. Sissano, Jar-Shyoung Lin, Mikhail Agamalyan

William MacKnight