The burning question of aircraft insulation
include DuPont's Tedlar—have held up better, FAA says. The molecules in the film lose hydrogenfluoridewhen heated. What's left is a polymer with carbon-carbon double bonds in its backbone, which chars in the presence of acid, Pearce tells C&EN. It's also believed, he says, that the HF helps convert the hot radicals involved in the burning process to less reactive species, acting as an effective flame quencher. However, HF, being extremely corrosive and poisonous, "has its problems," Pearce says. Finally, the most promising—and most expensive—material is a polyimide film (DuPont's version is known as Kapton). The material's numerous aromatic rings cause it to undergo the desired, char-producing condensed-phase reactions, Pearce says. Currently, only Lockheed's L-1011 aircraft uses polyimide
films, which have so far outperformed the otherfilmsin FAA tests. FAA also has tested an acrylic fiber— an oxidized polyacrylonitrile known as Curlon—as a substitute for the insulating fiberglass. FAA scientists found that Curlon—which was developed by Union City, Calif.-based Orcon Corp. but is not yet commercialized—combined with the polyimide film, was the most fire resistant of the insulations tested. The polyimide-Curlon combination showed a startling ability to stave off an outside fire burning into the cabin for over five minutes, compared with just two minutes using existing insulating blankets, FAA scientists say. After FAA finishes its final tests, the agency plans to develop a new standard for insulation. It hopes to issue a proposed standard by June 1999. Elizabeth Wilson
Monsanto, Rhone-Poulenc court analysts favor
says Monsanto is arranging thefinancingit needs and also plans to divest noncore assets. Neither he nor Shapiro would say which assets might be sold. Beginning in 2000, Crittenden says, Monsanto expects to see a rapid increase in net income as the company absorbs and benefits from its seed company acquisitions and as new pharmaceutical and biotechnology products come to market. Rhone-Poulenc's Alain Godard, chairman of the plant and animal health sector, told analysts that "new low-dose and more environmentally friendly crop protection products combined with new biotech offerings will lead to average sales growth of 6 to 7% per year through 2003." Two new "blockbuster" chemical products alone, Regent fipronil—a lowdose broadspectrum insecticide—and Balance isoxaflutole herbicide, together will contribute $1 billion in sales by 2003. Godard says Rhone-Poulenc's agricultural biotechnology plan is morefiscallyconservative than those of its competitors. The company does not plan to make the enormous investments in seed companies that competitors such as Monsanto and AgrEvo have made. Instead, it prefers to develop new plant traits, such as genes for herbicide tolerance, that would have seed companies beating a path to Rhone-Poulenc's door. MarcReisch
Following the ocean crash of Swissair Flight 111 near Halifax, Nova Scotia, last month, the Federal Aviation Administration (FAA) is recommending that airlines install more flame-resistant insulation in their aircraft. Although the exact cause of the crash is still unknown, smoke has been implicated as a contributing factor and insulation as a possible culprit. For several years, there has been concern that some of the polymer films used in aircraft insulation might be more flammable than thought. Scientists are now stepping up their scrutiny of the chemical and thermal properties of a number of potential replacement materials. Following this more extensive testing, FAA most likely will make its recommendation a requirement, which some observers estimate could cost more than $1 billion to implement. The basic structure of airplane insulation, which is used to damp noise and protect the passenger cabin from heat and cold, is a swath of lightweight fiberglass encased in a thin metallized polymer Monsanto and Rhone-Poulenc executives film—similar to insulation used in houses. held back-to-back meetings in New York Although the polymers themselves City last week to assurefinancialanalysts don't burn, the volatile products they emit of their strong commitment to the life when they're exposed to flame do, says Eli sciences. M. Pearce, university professor of polymer Monsanto told analysts chemistry and chemical engineering at that the breakup with Polytechnic University in Brooklyn, N.Y. American Home Products Thus the goal is to design a material that earlier this month (C&EN, produces condensed products instead of Oct. 19, page 14) will not volatiles, he explains. Pearce chaired a Na- stymie the company's tional Research Council committee that is- commitment to growth. sued a report in 1995 on improved fire- "We intend to sustain and smoke-resistant materials for commer- strong financial results cial aircraft interiors. What scientists want from our core businesses, is a polymer film that tends to "char" in- using those funds to develstead of melting and converting to volatile op and launch new prodmaterials that can burn. ucts," said Robert B. ShaIn much of the aircraft insulation now piro, chairman and chief Godard in use, fiberglass is coated with metal- executive officer. lized polyethylene terephthalate (a polyMonsanto Chief Fiester film such as DuPont's Mylar) or a nancial Officer Gary Crittenden assured metallized polyvinylfluoridefilm. the audience that Monsanto could afThe insulation coated with polyester ford to continue to invest in promising film is the least expensive. But FAA scien- products and technologies. He added tists say the material failed in eight lab that the company has every intention of tests, including FAA's standard Bunsen completing pending acquisitions of burner test, in which the insulation is four seed companies, including the held over a flame, and a newer test $2.3 billion purchase of the balance of called the "cotton-swab test," in which a DeKalb Genetics, and of launching new burning, alcohol-soaked cotton swab is drugs, including a new antiarthritis drug, Celebra. held in a crease of the insulation. The polyvinylfluoridefilms—which To make those investments, Crittenden
OCTOBER 26, 1998 C&EN 11
