Transient Interfacial Phenomena in Miscible Polymer Systems (TIPMPS) John A. Pojman University of Southern Mississippi Vitaly Volpert Université Lyon I Hermann Wilke Institute of Crystal Growth, Berlin A flight project in the Microgravity Materials Science Program 2002 Microgravity Materials Science Meeting June 25, 2002
53
Embed
Transient Interfacial Phenomena in Miscible … › TIPMPS › tipmps_June_2002.pdfMany polymer processes involving miscible monomer and polymer systems could be affected by fluid
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Transient Interfacial Phenomena in MisciblePolymer Systems
(TIPMPS)
John A. Pojman
University of Southern Mississippi
Vitaly Volpert
Université Lyon I
Hermann Wilke
Institute of Crystal Growth,
Berlin
A flight project in the Microgravity Materials Science Program
Can gradients of composition and temperature inmiscible polymer/monomer systems create
stresses that cause convection?
3
Why?The objective of TIPMPS is to confirm Korteweg’smodel that stresses could be induced in miscible fluidsby concentration gradients, causing phenomena thatwould appear to be the same as with immiscible fluids.The existence of this phenomenon in miscible fluidswill open up a new area of study for materials science.
Many polymer processes involving miscible monomerand polymer systems could be affected by fluid flowand so this work could help understand misciblepolymer processing, not only in microgravity, but alsoon earth.
4
How
An interface between two miscible fluids will be becreated by photopolymerization, which allows thecreation of precise and accurate concentration gradientsbetween polymer and monomer.
Optical techniques will be used to measure therefractive index variation caused by the resultanttemperature and concentration fields.
5
Impact
Demonstrating the existence of this phenomenon inmiscible fluids will open up a new area of study formaterials science.
“If gradients of composition and temperature in misciblepolymer/monomer systems create stresses that causeconvection then it would strongly suggest that stress-inducedflows could occur in many applications with miscible materials.The results of this investigation could then have potentialimplications in polymer blending (phase separation), colloidalformation, fiber spinning, polymerization kinetics, membraneformation and polymer processing in space.”SCR Panel, December 2000.
6
Science Objectives
• Determine if convection can be induced byvariation of the width of a miscible interface
• Determine if convection can be induced byvariation of temperature along a miscibleinterface
• Determine if convection can be induced byvariation of conversion along a miscibleinterface
7
Surface-Tension-InducedConvection
convection caused by gradients in surface(interfacial) tension between immisciblefluids, resulting from gradients inconcentration and/or temperature
high temperature low temperature
fluid 1
fluid 2
interface
8
Consider a Miscible “Interface”
x
y
“interface” = ∂C/∂y
C = volume fraction of A
fluid A
fluid B
9
Can the analogous process occurwith miscible fluids?
high temperature low temperature
fluid 1
fluid 2
10
Korteweg (1901)• treated liquid/vapor interface as a
continuum
• used Navier-Stokes equations plus tensordepending on density derivatives
• for miscible liquid, diffusion is slow enoughthat “a provisional equilibrium” could exist(everything in equilibrium except diffusion)– i.e., no buoyancy