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Search Publications by: Alamgir Karim (Assoc)

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Displaying 76 - 100 of 100

Combinatorial Study of Surface Pattern Formation in Thin Block Copolymer Films

July 1, 2001
Author(s)
A P. Smith, Jack F. Douglas, J C. Meredith, Eric J. Amis, Alamgir Karim
Surface pattern formation in thin diblock copolymer films is investigated utilizing a high-throughput methodology to validate the combinatorial measurement approach for polymer science. Measurement libraries of block copolymer films having gradients in

Suppression of Lateral Phase Separation in Thin Polyolefin Blend Films

March 1, 2001
Author(s)
Y A. Akpalu, Alamgir Karim, Sushil K. Satija, N P. Balsara
The effectiveness of a compatibilizer in suppressing lateral phase separation in thin polyolefin blend films is investigated as a function offilm thickness and temperature. Neutron and x-ray reflectivity measurements were made on spun cast thin blend films

Polymer-Clay Nanocomposite Materials: Solution and Bulk Properties

January 1, 2001
Author(s)
G Schmidt, A Nakatani, Paul Butler, V Ferreiro, Alamgir Karim, Charles C. Han
The influence of shear on viscoelastic polymer-clay solutions was investigated by means of small-angle neutron scattering (SANS) under shear. SANS measured the shear-induced orientation of polymer and platelets. With increasing shear rate an anisotropic

Combinatorial Materials Science for Polymer Thin-Film Dewetting

December 1, 2000
Author(s)
J C. Meredith, A P. Smith, Alamgir Karim, Eric J. Amis
A combinatorial technique is described for rapid measurement of phenomena associated with thin-film polymer science. Thin-film libraries of polystyrene on silicon, containing systematic variations in film thickness and temperature, are prepared with a

Modification of the Phase Stability of Polymer Blends by Fillers

November 1, 2000
Author(s)
Alamgir Karim, D W. Liu, Jack F. Douglas, A Nakatani, Eric J. Amis
We investigate the influence of surface modified filler particles on the phase stability of a model blend of polystyrene (PS) and polybutadiene (PB). The upper critical solution cloud point curve of PS/PB is destabilized (upward shift of critical

AFM Studies of Confined Dewetting On Gradient Patterned Surfaces

August 1, 2000
Author(s)
Alamgir Karim, A Sehgal, Eric J. Amis
Spinodal dewetting of ultra thin films driven by thermal fluctuations is considered analogous to phase separation accompanied by composition fluctuations. Such dynamic processes are extremely sensitive to perturbation by external fields. In this study

High-Throughput Measurement of Polymer Blend Phase Behavior

August 1, 2000
Author(s)
J C. Meredith, Alamgir Karim, Eric J. Amis
Two-dimensional combinatorial thin film libraries are used to rapidly measure the LCST phase boundary of polystyrene and poly (vinylmethyl ether) blends in compositin-temperature space. The film libraries with continuous gradients in polymer blend

Shear Orientation of a Visoelastic Polymer-Clay Solution

August 1, 2000
Author(s)
G Schmidt, A Nakatani, Paul Butler, Alamgir Karim, Charles C. Han
The shear orientation of viscoelastic clay-polymer solutions was investigated by means of rheology, flow birefringence (δn) and small-angle neutron scattering (SANS). Oscillatory shear showed a linear viscoelastic region and flow occured at higher stresses

Transient Target Patterns in Phase Separating Filled Polymer Blends

September 1, 1999
Author(s)
Alamgir Karim, Jack F. Douglas, G Nisato, D W. Liu, Eric J. Amis
Recent simulations have indicated that the presence of filler particles in a phase separating blend can induce the development of composition waves having the symmetry of the filler particles. We investigate these predictions through atomic force
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