A professor at Case Western Reserve University in Cleveland believes he has developed a new class of fire-resistant polybenzoxazine thermoset resin that may challenge phenolics andepoxy resins in the structural-parts market. ``The large market potential includes printed circuit boards, electrical appliances, wood adhesives and carbon-carbon applications,'' Hatsuo Ishida, professor of macromolecular science, said in a telephone interview from his Cleveland office.
The material ``is almost as good as polyimide [high-temperature thermoplastic], and it has an extremely wide property range.''
Ishida's breakthrough was putting two benzoxazine rings on the same monomer. Now, he faces the challenge of identifying the most cost-effective combinations among dozens of possible chemical properties.
Ishida's laboratory has produced about 100 pounds of the polybenzoxazine thermoset, and a company used its 400-liter reactor to make 300 pounds.
``Interested companies can evaluate [the material] with a se-crecy agreement,'' Ishida said.
Thick parts of the thermoset can be produced without the voids or gaps that can appear in phenolic laminates.
Ishida uses a known chemical reaction of benzoxazine ring formation and achieves low-temperature reactions to put two rings on a monomer.
The benzoxazine monomers are thermally cured with or without a catalyst via a ring-opening polymerization. The monomers are transformed into phenolic compounds and become a cross-linked material such as a phenolic or epoxy.
Claimed advantages are numerous. The process avoids generating water molecules, a bane to fabricators. It is said to reduce the presence of the free-formaldehyde molecule, a workplace health hazard. And it reportedly achieves near-zero shrinkage, a benefit in manufacturing.
In July, the Federal Aviation Administration awarded a $1.92 million grant over five years to continue the research at Case Western Reserve University. Schneller Inc., based in Kent, Ohio, will provide an additional $80,000-$100,000 of in-kind services.
The FAA has interest in how the thermoset burns more slowly and emits less gas than existing materials in aircraft interiors, according to Richard Lyon, FAA program manager for fire-resistant materials. The material potentially gives passengers more time to exit an aircraft in an emergency.
The FAA has been seeking inexpensive fire-resistant materials designed to increase aircraft safety.
Schneller, a major supplier of decorative plastic laminates for airplane interiors, is performing tests to quantify the material's fire resistance, according to Dale Onderak, vice president of research and development.
He believes the material will be a winner if Ishida can hold down costs while retaining the positive attributes.
``Will he be able to scale up and make it cost effectively?'' Onderak said.
Ishida, who began the research in 1989 and holds 1992 and 1993 patents on the technology, said some polybenzoxazine thermoset has produced a char-yield of 85 percent. That compares with a 55 percent char-yield from traditional phenolic resins used in aircraft cabin side panels, roofs, overhead bins and cabin dividers.
Development could occur quickly. Polybenzoxazines use generally inexpensive and readily available chemicals.
``The chemistry is so simple,'' the FAA's Lyon said. ``Phenols, formaldehyde and primary amines are very inexpensive.''
The Brecksville, Ohio-based Edison Polymer Innovation Corp. has an avid interest in the development.
Case Western Reserve, Schneller and the University of Akron are among the members of the nonprofit corporation supporting polymer research and product introduction.