THE CHEMICAL WORLD THIS WEEK
tenance costs should be no more than $1000 a year for the sole operation of vacuuming the turf. The only concern other than contact burns (which were prevented by elbow padding and knee-length stockings) was a gradual darkening of the field, seen more at Tennessee than at Wisconsin. Tartan is composed of green and black nylon fibers. During use, 3M postseason studies found, the top few millimeters of the green fiber were breaking off, giving more exposure to the black. The cause of the breakage goes back to the production process, 3M says. At any rate, 3M is assuring both Tennessee and Wisconsin that their teams will be playing on green turf next year, as part of the five-year guarantee. In time, the entire Tennessee field may have to be replaced. MICROWAVE CURING:
Ballbats from Weeds Some may think that an Oregon Slammer is vaguely related to a Washington apple knocker. But baseball buffs will recognize it as the tradename of a baseball bat made in the Beaver State. What they will not know, quite likely, is that microwave power is now playing a key role in the bat's production. This month, Tanoak Industries, Inc., of Harbor, Ore., put the first of its microwave-cured bats on the market. The move is significant on a number of counts. For one thing, it marks yet another industrial outlet for microwave technology, which many contend has a promising and lucrative future. For another, it thrusts tanoak into the limelight as being a valuable hardwood source, a sharp turnaround
from its rating, until now considered to be something of a weed in contrast to its more useful arboreal neighbors. "When fully cured, tanoak is harder than white ash yet practically as resilient," notes James G. Richmond, Tanoak Industries' president. In fact, tanoak is in the same class as white ash and the other U.S. hardwoods, hickory and maple, on the basis of unit weight (specific gravity is lower), modulus of rupture, and modulus of elasticity, and it shares many of the qualities of red and white oak. Perbillet cost of microwave-cured tanoak is comparable to the cost of the other hardwoods. Tanoak (Lithocarpus densiflorus) is native to the coastal regions of northern California and southern Oregon. Its name is something of a misnomer because it isn't a member of the oak family. Until now, the problem associated with the wood has been its wetness. A water content in green logs of well over 50% isn't uncommon. Splitting of the wood often accompanies conventional kiln drying methods, which can take anywhere from 60 days to 18 months. Microwave curing changes all that, points out Dr. Carl M. Olsen, manager of applications development at Varian Associates' industrial microwave operation in San Carlos, Calif., who played a prominent role in developing the new tanoak curing process in conjunction with Tanoak Industries. Residence time in a microwave kiln now takes a scant four hours (followed by a few additional days in a hot-air oven). And there are other advantages. The faster cure time increases the wood's fiber density and the "springiness" of the final product. Varian designed and built Tanoak Industries' entire curing systempower pack, 30-kw. klystrons that generate 2450-MHz. microwaves, auto-
Oregon Slammers
Loading the radar kiln 14 C&EN JAN. 27, 1969
matic controls, and modifications to the kiln. The microwaves penetrate the wood, generating heat evenly throughout as the result of the molecular jostling they induce. The net effect is faster, more uniform drying. Supplies of tanoak should create no problem well into the future. Current estimates put reserves of the wood at about two billion board feet. CHROMATOGRAPHY:
Lasers for Pyrolysis GC That "solution in search of a problem," the laser, may have found another problem that it can help to solve—this time in pyrolysis gas chromatography. When used to pyrolyze samples for GC, instead of the usual heated filament or electric furnace, the laser yields chromatograms that show simpler patterns and allow greater distinctions to be made between similar substances, O. F. Folmer, Jr., told the 50th International Symposium on Advances in Chromatography in Las Vegas. The problem is that in the electrically heated apparatus used by almost all investigators, the heating rate is relatively slow. Thus, according to Mr. Folmer and Leo V. Azarraga of Continental Oil, there is opportunity for secondary reactions that can complicate the chromatogram pattern. Another complication is that there are almost as many different pieces of heating apparatus as there are investigators. Since breakdown depends on the heating rate, which depends on the apparatus, comparing results from different labs is often difficult. Mr. Folmer and Mr. Azarraga reason that the laser may be the answer because very high temperatures can be reached in microseconds, and the plume of ejected material cools almost as fast, leaving little time for troublesome secondary reactions. They tested their hypothesis on a number of materials, using a pulsed ruby laser built by Continental Oil's electronics group. Chromatograms were run also on the same materials using a heated filament and a tube furnace as the pyrolysis apparatus. The most interesting results came from comparing sets of similar materials pyrolyzed in the three different ways. In one set, for example, DYLT polyethylene and black polyethylene tubing, the laser chromatograms show major differences, whereas those from each of the other pyrolysis methods were nearly identical. The pyrolysis GC in the latter cases was of little or no help in distinguishing the materials. They obtained similar results with other sets of similar materials.
