Virginia Tech researcher reports nano-particle dispersion technique improves polymers

August 29, 2005

Blacksburg, Va. -- There is a lot of excitement about incorporating nano particles into polymers because of the ability to improve various properties with only a small percent of the particles. "You can improve the barrier to gases, such as hydrogen, carbon dioxide, and oxygen. You can increase material strength with little increase in weight," said Don Baird, professor of chemical engineering at Virginia Tech.

But there are problems. "While 1 percent by weight of nano particles will change a material's properties dramatically, 2 or 3 percent provides hardly any additional enhancement," he said. "The particles just clump together, and thereby reduce the advantages associated with the surface area of single particles."

Another problem is that the incorporation of nano particles changes a polymer's flow properties leading to potential processing problems.

Baird's research group at Virginia Tech has developed a method for improving the dispersion, or exfoliation, of individual nano particles into polymers. He will present his research at the 230th American Chemical Society National Meeting, held in Washington, D.C., Aug. 28-Sept. 1. "The paper will present how we are dispersing nano particles and how we are using flow properties to monitor dispersion," he said.

Using supercritical carbon dioxide, the researchers are able to exfoliate nano particles at higher concentrations, leading to further enhancement of mechanical properties than presently possible using just mechanical mixing. "Carbon dioxide is soluble in a lot of polymers. It attaches to the particles so they don't attach to each other, and helps disperse the particles throughout the polymer. It is a benign, natural substance," Baird said.

The rheological properties including the normal stresses (elastic properties) and the stress relaxation response are used to monitor particle dispersion.

The researchers also have discovered that the changed flow behavior is good news - an indication that the material will exhibit improved mechanical properties.

Baird's team observed that nano clay particles well dispersed in polypropylene and polycarbonate plastics tend to promote polymer chain orientation, or alignment, and then retard relaxation or loss of orientation. "The result is they make the polymer chains act like longer or higher molecular weight chains. The material is stronger than one would expect given the size of a polymer chain."

Pointing to a bobbin of fiber, Baird said, "If that contained nano particles and was stretched, it is possible that the fiber could be woven into a vest that would stop a bullet. An ordinary polymer material with well dispersed high levels (8 wt%) of nano particles could have exceptional mechanical properties."

He will present the paper, "Effects of nano clay particles on non-linear rheology of polymer melts (Poly 248)" at 11:20 a.m. Monday, Aug. 29, in the Grand Hyatt Constitution room D-E, as part of the Herman Mark Award program honoring Don Paul.

Learn more about Baird's research at http://www.che.vt.edu/baird/baird.htm
-end-


Virginia Tech

Related Polymers Articles from Brightsurf:

Seeking the most effective polymers for personal protective equipment
Personal protective equipment, like face masks and gowns, is generally made of polymers.

Ultraheavy precision polymers
An environmentally friendly and sustainable synthesis of ''heavyweight'' polymers with very narrow molecular weight distributions is an important concept in modern polymer chemistry.

FSU researchers help develop sustainable polymers
Researchers at the FAMU-FSU College of Engineering have made new discoveries on the effects of temperature on sustainable polymers.

Structural colors from cellulose-based polymers
A surface displays structural colors when light is reflected by tiny, regular structural elements in a transparent material.

Growing polymers with different lengths
ETH researchers have developed a new method for producing polymers with different lengths.

Exciting new developments for polymers made from waste sulfur
Researchers at the University of Liverpool are making significant progress in the quest to develop new sulfur polymers that provide an environmentally friendly alternative to some traditional petrochemical based plastics.

Polymers can fine-tune attractions between suspended nanocubes
In new research published in EPJ E, researchers demonstrate a high level of control over a type of colloid in which the suspended particles take the form of hollow, nanoscale cubes.

Functional polymers to improve thermal stability of bioplastics
One of the key objectives for contemporary chemistry is to improve thermomechanical properties of polymers, in particular, thermostability of bioplastics.

Fluorescent technique brings aging polymers to light
Modern society relies on polymers, such as polypropylene or polyethylene plastic, for a wide range of applications, from food containers to automobile parts to medical devices.

Polymers to the rescue! Saving cells from damaging ice
Research published in the Journal of the American Chemical Society by University of Utah chemists Pavithra Naullage and Valeria Molinero provides the foundation to design efficient polymers that can prevent the growth of ice that damages cells.

Read More: Polymers News and Polymers Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.