Notes from the Lab


LEARNING ABOUT LIGHT-EMITTING POLYMERS

Light-emitting polymers could one day have important applications in computer displays by providing lightweight and flexible display mechanisms at low cost. They also have important implications in the design of large-area displays for the next generation of electric billboards, road signs and public message systems.

Currently, however, these polymers are limited by a short operating lifetime. Under certain conditions, such as the presence of oxygen and light, they slowly self-degrade.

Graduate student Brian Cumpston and Professor Klavs Jensen of the Department of Chemical Engineering are using spectroscopic and modeling techniques to understand bulk and interface degradation processes in electroluminescent polymer devices. Recently they proposed a mechanism for how one such polymer degrades. They have also studied which properties of the polymer make it susceptible to attack by oxygen; results indicate that changing some of the chemical groups attached to the polymer might improve its stability. The researchers note, however, that more studies should be conducted on the effect of such changes on the polymer's ability to emit light.

Professor Jensen also has an appointment in the Department of Materials Science and Engineering. The work is funded by the Office of Naval Research. (Source: Materials Processing Center Industry Collegium Report)

COMPUTER MODELS AID THE RAILROADS

Computer models developed by MIT engineers are helping the railroad industry answer a variety of questions such as whether it is economically worthwhile to use heavier cars.

One of these models, TRACS (Total Right of Way Analysis and Costing System), provides a way to translate detailed research concerning factors such as rail wear rates into managerial decisions about track maintenance. For example, it predicts how long track components will last and what it will cost to replace them. TRACS can also be used to create engineering budgets and conduct technology assessments, such as where to best use advanced or standard components.

Recently the MIT researchers and colleagues used TRACS and other models to determine the economic benefits of heavier cars. Tracks today can accommodate cars that weigh 315,000 pounds. The researchers concluded, however, that "it makes some sense to go to heavier loads in the intermediate level of 263,000-286,000 pounds, but not to the 315,000-pound car," said Carl Martland, a senior research associate in the Department of Civil and Environmental Engineering and program manager for the MIT Rail Group.

The work is supported by the Association of American Railroads. (Source: Civil and Environmental Engineering at MIT)

A version of this article appeared in MIT Tech Talk on March 20, 1996.


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