Navigation Links
New theory may shed light on dynamics of large-polymer liquids
Date:8/23/2011

CHAMPAIGN, Ill. A new physics-based theory could give researchers a deeper understanding of the unusual, slow dynamics of liquids composed of large polymers. This advance provides a better picture of how polymer molecules respond under fast-flow, high-stress processing conditions for plastics and other polymeric materials.

Kenneth S. Schweizer, the G. Ronald and Margaret H. Professor of materials science and engineering at the University of Illinois, and graduate student Daniel Sussman published their findings in the journal Physical Review Letters.

"This is the first microscopic theory of entangled polymer liquids at a fundamental force level which constructs the dynamic confinement potential that controls slow macromolecular motion," said Schweizer, who also is a professor of chemistry and of chemical and biomolecular engineering and is affiliated with the Frederick Seitz Materials Research Laboratory at the U. of I. "Our breakthrough lays the foundation for an enormous amount of future work relevant to both the synthetic polymers of plastics engineering and the biopolymers relevant to cell biology and mechanics."

Polymers are long, large molecules that are ubiquitous in biology, chemistry and materials, from the stiff filaments that give cells their structure to plastics. Linear polymers fall into two classes: rigid rods like uncooked spaghetti or flexible strands like al dente noodles.

When in a dense solution, linear polymers become entangled like spaghetti in a pot, intertwining and crowding each other. Each polymer is hemmed in by its neighbors, so that the liquid behaves like an elastic, viscous rubber. Given enough time, the liquid will eventually flow slowly as polymers crawl along like snakes, a movement called reptation. Researchers have long assumed that each polymer's reptation is confined to a tube-shaped region of space, like a snake slithering through a pipe, but have had difficulty understanding how and why the polymers behave that way.

Schweizer and Sussman's new theory, based on microscopic physics, explains the slow dynamics of rigid entangled polymers and quantitatively constructs the confining dynamic tube from the forces between molecules. The tube concept emerges as a consequence of the strong interactions of a polymer with its myriad of intertwining neighbors. The theory's mathematical approach sheds greater light on entanglement and better explains experimental data.

"Our ability to take into account these crucial physical effects allows us to predict, not assume, the confining tube concept, identify its limitations, and predict how applied forces modify motion and elasticity," Schweizer said.

Not only does the new theory predict tube confinement and reptative motion, it reveals important limitations. The researchers found that the "tubes" weaken as applied forces increase, to the point where the tube concept fails completely and the liquid loses its rubbery nature. This is particularly important in plastics processing, which exposes polymer liquids to high stress conditions.

Next, the researchers plan to continue to study how external stress or strain quantitatively determine the driven mechanical flow behavior of entangled polymer liquids. They also hope to develop a theory for how attractive forces can compete with entanglement forces to result in soft polymer gels.


'/>"/>

Contact: Liz Ahlberg
eahlberg@illinois.edu
217-244-1073
University of Illinois at Urbana-Champaign
Source:Eurekalert  

Related biology news :

1. Revised theory suggests carbon dioxide levels already in danger zone
2. Scientists present moving theory behind bacterial decision-making
3. No place like home: New theory for how salmon, sea turtles find their birthplace
4. Nearly a century later, new findings support Warburg theory of cancer
5. Rethinking the genetic theory of inheritance
6. Researchers disprove 15-year-old theory about the nervous system
7. Clarke clarifies pattern recognition theory
8. Rumbaughs theory links positions of Wilson, Skinner
9. MS study offers theory for why repair of brains wiring fails
10. New theory gives more precise estimates of large-scale biodiversity
11. New theory on why male, female lemurs same size
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
New theory may shed light on dynamics of large-polymer liquids
(Date:2/16/2017)... 16, 2017  Genos, a community for personal ... has received Laboratory Accreditation from the College of ... to laboratories that meet stringent requirements around quality, ... processes. "Genos is committed to maintaining ... We,re honored to be receiving CAP accreditation," said ...
(Date:2/9/2017)... 2017 The biomass boiler market report by ... boiler market globally in terms of revenue (US$ Mn) ... market for biomass boilers has been segmented on the ... country/region. The market based on feedstock type, has been ... & energy crops, urban residues, and others. On the ...
(Date:2/8/2017)... Report Highlights The global biosurgery ... billion in 2016 at a compound annual growth rate ... Includes - An overview of the global market for ... from 2015 and 2016, and projections of compound annual ... market on the basis of product type, source, application, ...
Breaking Biology News(10 mins):
(Date:2/22/2017)... Fort Washington, PA (PRWEB) , ... ... ... The Omnia-Prova Education Collaborative (TOPEC), the leading medical education provider of ... Accreditation with Commendation by the Accreditation Council for Continuing Medical Education (ACCME). ...
(Date:2/22/2017)... 2017 Dublin - ... Biological Crop Protection (Bio-Pesticide) Market-By Type, By Application, By End User, ... their offering. ... Global Biological Crop Protection Market is forecasted to grow at a ... in biopesticide or biological crop protection market is driven by the ...
(Date:2/22/2017)... ... February 22, 2017 , ... ... of Tom Perkins as European director. Operating from Pennside’s Zurich headquarters, Pennside Partners, ... , Perkins joins Pennside after more than a decade with leading market research ...
(Date:2/21/2017)... , Feb. 21, 2017 /PRNewswire/ - SQI Diagnostics Inc. ("SQI" or ... operational results for the three months ended December 31, 2016. ... -based life sciences and diagnostics company that develops and commercializes ... ... to build on the commercial milestones achieved in fiscal 2016," ...
Breaking Biology Technology: