The U.S. Navy needs lighter materials so ships will go further faster. One way to do that is to use new composite materials. But how will these materials respond to fire—one of the most critical safety concerns on a ship? Virginia Tech material scientists have developed models to test composites for fire resistance – and have a recommendation.

John Bausano, a doctoral student in the chemistry-engineering interdisciplinary Macromolecular Science and Infrastructure Engineering program at Virginia Tech, will present his research in the Excellence in Graduate Polymer Science Research Symposium at the 231st American Chemical Society National Meeting in Atlanta on March 26-30.

Working with Jack Lesko, associate professor of engineering science and mechanics in the College of Engineering, Bausano developed a testing method – a one-sided heat flux test that can be used on a sample as small as one inch by six inches (1x6") to test a commercially available material – E-glass vinyl ester composite laminates. One side of the material is heated to simulate fire on one side of a wall. A load is placed on one edge to simulate a load-bearing wall.

"We measure the deflection, failure, and how hot it gets on the cool side," said Bausano. "That is an important issue because you don't want the fire to spread."

His findings are that the composite material being tested does localize heat, "especially compared to steel, which conducts heat in all directions."

His recommendation as other materials and processing are considered is, "Develop the material with as high a glass transition (Tg) temperature as you can in order to sustain structural rigidity. That would help the engineers and the sailors. The longer the material stays below Tg, or the softening point, the longer the wall will stand. Tg is the upper temperature level of usefulness."

Composite materials would also be useful on oil platforms, where fire is also a concern, he said.

The poster, "Composite life under sustained compression and one-sided simulated fire exposure: Characterization and prediction" (POLY 187), will be presented from 6 to 8 p.m., Sunday, March 26, in the Georgia World Congress Center Exhibit Hall B4.

American Chemical Society Abstract

This paper addresses the experimentally measured lifetime of E-glass vinyl ester composite laminates subjected to combined centric compression and one-sided simulated fire exposure. Under such conditions, these laminates (having a pseudo quasi-isotropic stacking sequence) support a 10 MPa compressive stress under low heat fluxes (20-30 kW/m2) for approximately 102 seconds(1). Thermally modified micromechanics and laminate mechanics are successfully used to describe the observed life times when limited to thermally reversible effects. Inclusion of time effects is considered with the inclusion of elevated temperature creep effects. In these cases, the glass transition temperature of the matrix material is the dominant factor that controls the life the composite under load.


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