be determined to demonstrate toxicological safety. One of these, traces of soluble polymer in extracts of the resin material, was a considerable challenge. Since macromolecules are not usually amenable to chemical reactions or other techniques commonly applied to trace analysis, Dr. Gaylor used infrared spectroscopy. The 2245-cmr 1 absorption band is highly specific for the nitrile group and was potentially a selective method for nitrile polymer, Dr. Gaylor says. The source of extracted polymer is the residue from evaporation used for a gravimetric measurement of total nonvolatile extractives. The weighed residue was redissolved in acetone and then evaporated onto potassium bromide. After drying, the potassium bromide was pressed into a pellet and analyzed on a high-resolution, doublebeam, grating spectrophotometer. The method was calibrated with solutions containing known amounts of resin. Of three techniques, directly evaporating an acetone solution onto potassium bromide gives the best precision. Sometimes sample selection can be a greater problem than actual analysis. In response to an FDA request for data on heavy metal contents of paints and other surface coatings, Richard W. Scott and associates at SherwinWilliams submitted data on metals in 98 paints within 31 working days. Among the problems, some of the actual
Variety of techniques helped remedy auto paint dulling problem
analytical work was done at noncompany laboratories and the resulting data indicated that not all were using the same methods. Thus, following evaluation of initial data on seven representative paints, a single consulting laboratory was chosen to analyze for mercury, cadmium, arsenic, and selenium, while the in-house laboratory would handle lead, antimony, and barium. Then, Mr. Scott selected some 91 more coating systems that represented a complete cross section of the company's product line as it was defined by FDA in asking for the data. A major undertaking was gathering samples from various warehouses and preparing for analyses. In the end, all the methods used proved to have a sensitivity of 0.01% of the metal found after sample digestion. Precision between duplicate determinations was within the ±10% tolerance level asked for by FDA. Dulling (loss of gloss) of auto paints has long been a well-known problem. The cure also has long been well known —remove some of the outer material to restore the shine. An explanation of what causes the dulling and how results of actual tests in Florida might be correlated with accelerated test methods comes from work of Dr. W. Thomas Lewis and Dr. Edward C. Ferlauto of Mobil Chemical. From results of work with infrared attenuated total reflectance techniques, and scanning electron and transmission electron microscopy techniques, Dr. Lewis speculates that the cause is loss of a small amount of the plasticizer in the top of the paint (on the order of several molecular layers). Loss of the plasticizer allows light-scattering properties of colloidal macrocrystalline polymers or agglomerates to become evident. The light-scattering properties of the agglomerates relate to the size and distribution of the agglomerates. These agglomerates are attributed to cellulose acetate butyrate in the paint formulation. Generally, they are larger and fewer as the time and temperature of baking the paint increase, Dr. Lewis says. If an agglomerate has a size of 2000 to 3500 A. and a distribution of three or four particles per square micron, the dulling on exposure for a maroon paint is minimized, he adds. Information such as this can lead to a suitable test that can be used for control purposes in coating operations. In addition, data and an understanding of the mechanism can aid formulators of acrylic polyester coating systems. Although these examples presented to the symposium are rather specific problems that have been solved, the area of analytical work requiring innovative techniques is all-encompassing, points out Dr. Lucchesi, who also served as chairman of the symposium. Many other examples are possible, he emphasizes. And many other solutions can be cited as having subsequent commercial use.
Methyl fuel could provide motor fuel
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FUEL—With the energy crisis focusing attention on development of new processes for production of synthetic natural gas and on nuclear reactors, the need for motor fuel options has been relegated to a back seat. However, Dr. David Garrett of VulcanCincinnati, Inc., believes that the means already exist for providing required quantities of motor fuels with little alteration of engines and with minimum interference with existing fuel production. The answer, he says, is methyl fuel. Methyl fuel is a mixture of methanol and controlled percentages of higher alcohols containing up to four carbon atoms. Dr. Garrett is proposing that all types of coal, coal tailings, and mine washings be processed to produce synthesis gas—a mixture of hydrogen, carbon dioxide, and carbon monoxide— that can be catalytically converted to methyl fuel. The process proposed by Dr. Garrett involves use of a flexible coal gasifier capable of handling all types of coal and capable of being operated to maximize production of carbon monoxide and hydrogen. The effluent gases are cleaned of particulates and sulfur compounds. The clean gas is converted to methyl fuel that has a cost competitive with substitute natural gas (SNG) while producing less pollutants when burned. The contemplated gasifier designs would be similar to those already being built on a pilot and commercial scale for the Bureau of Mines. They are designed to operate at low pressures and to produce synthesis gas rather than methane. Conventional synthesis gas cleaning and desulfurization processes would be used to treat the gasifier effluent. One of the strong selling points of the methyl fuel concept is the accrual of environmental benefits. Because the contemplated systems can use low-grade carbon sources, there would be less dumping of low-grade coal as waste. Comparisons of methyl fuel with No. 5 fuel oil indicate that methyl fuel provides cleaner materials with no particulates, reduced nitrogen oxides, reduced carbon monoxide emissions, no sulfur compounds, negligible quantities of aldehydes, acids, and unburned hydrocarbons, and the virtual elimination of soot. Another selling point, says Dr. Garrett, is that methyl fuel also can be effectively used to replace tetraethyllead as a motor fuel additive. Raw methyl fuel has a research octane number of 130 and can be blended with gasoline at up to 20% by volume. In addition to eliminating the lead emission problem, methyl fuel would extend the gasoline pool without sacrificing octane ratings or requiring significant engine adjustments. Methyl fuel, in quantity and at proSept. 17, 1973 C&EN
23
jected costs, can also be used in the tertiary treatment of waste water, Dr. Garrett says, particularly as a denitrification agent. As a boiler fuel and for use in turbine installations, methyl fuel has great potential, according to test indications. It also can be used as a feedstock for SNG plants with reduction of air pollution and considerable simpli fication of plant design. Methanol plant purge gas is rich in hydrogen and can be used in ammonia synthesis, metals refining, petroleum refining, and sulfur recovery. It is also a potentially attrac tive fuel for some types of fuel cells. Methyl fuel plant costs have been projected at $154 million upwards de pending on site conditions and utilities requirements. The lowest selling price for methyl fuel is estimated to be about 84 cents per million B.t.u. However, Dr. Garrett believes that more realistic estimates would be about $1.02 per million B.t.u. Dr. Garrett believes that the first place where methyl fuel will make an impact is in the motor fuel industry, and this may come before 1980. As many as 20 plants could be ready by that time if
the most optimistic estimates are cor rect. By 1990 the number could increase to 30 plants with an additional 60 plants possibly being employed to fuel the utilities industry. However optimistic the estimates may be, methyl fuel must still face an industry preoccupation with SNG plants based directly on coal. A ray of hope for the methyl fuel advocates, however, comes from potential problems with SNG plants. Fred L. Jones of Babcock & Wilcox Co. notes that with few exceptions, today's SNG processes are years away from commercialization or even demonstration. This lag is due primarily to the difficulty of proving out the catalytic methanation steps required for SNG production. According to Mr. Jones, the methyl fuel process consists of proved com ponents that have been commercially demonstrated and could be put into production rapidly. It may be that methyl fuel has arrived in time to fill the gap between conventional petroleum processing and eventual production of substitute natural gas and its derivative products.
Asahi develops plastic/mineral complexes Fillers for plastics got their start early on, when addition of wood flour to phenol-formaldehyde resin turned a highly brittle polymer into a practical molding material. More recent problems of incinerating plastics wastes have led in Japan to commercial development of highly mineral-filled plastics suitable for calendering into sheet stock for building and packaging products. Asahi Chemical Industry Co. is now going be yond such mechanical mixtures of resin and filler with its newly developed ther moplastic/mineral complexes.
\ ·
Previously, notes Dr. Itsuho Aishima, deputy general manager of Asahi Chem ical's plastics division, only nylon 66 was successful as a resin base for highly filled molding materials. Asahi's new resin/inorganic bonding process extends the choice to other resin bases, including polyolefins and nylon 6. Called Loymers, the new line is available in pellet, rod, and sheet form. They're suitable for processing by any standard molding technique (C&EN, Sept. 10, page 11). Ten grades are now being test mar keted in Japan. One series, based on
high-density polyethylene, competes with ordinary polyolefins for uses such as bottles, food packaging, and other disposable housewares. Development price for these grades runs around 34 cents a pound. Another Loymer series, using high-density polyethylene or nylon 66 as base, is contending for engineering applications. Current price is about 76.5 cents a pound for nylon 66-base mate rial. Asahi has been supplying Loymers from a 3000 metric-ton-a-year pilot unit since March, and it plans to complete a full-scale plant of 20,000- to 30,000metric-ton capacity by early 1975. Mineral content (inorganic com pounds of elements such as aluminum, magnesium, and silicon) of the com plexes ranges from about 40 to 70%, de pending on grade. Unlike mineral/resin mixtures of high inorganic content, Dr. Aishima tells C&EN, Loymer complexes don't require elastomeric additives to avoid unacceptably high brittleness in the product. A major advantage Asahi claims over such mixtures, in fact, is an inherently better balance of stiffness and toughness (bending modulus and impact strength), coupled with high heat-distortion temperature. Nor do Loymers need special flame-retarding additives to meet Underwriters Labora tories specifications for nonflammability. And engineering grades based on high-density polyethylene, like the highmolecular-weight polyethylene already used in engineering applications, show broad resistance to chemical attack. Among engineering plastics, though, Loymers show the lowest resistance to abrasion. Ten years of R&D in resin/mineral molding compounds went into Asahi Chemical's new line. Pending publica tion of Japanese patent applications covering bonding techniques, the com pany will say little about the nature of
Loymer R
Resin/mineral bonding improves properties
Nylon 66 Polyacetal
Z5
"D Ο
ω cû
Acrylonitrile-butadiene-styrene high-modulus) Polypropylene > | Loymer R Loymer S • ^ Acrylonitrile-butadiene-styrene ^(high-impact) Polystyrene ^ υ- u -%. (high-impact) High- ^ ^ density X ^ w • ΝΥ|οη 6 polyethylene Medium-density polyethylene
Impact strength
24
C&EN Sept. 17, 1973
In choosing the plastic for an end use, it's a trade-off be tween stiffness and toughness. Rigid resins tend to be brittle; tough resins have poorer dimensional stability. In their balance of these two properties, polyolefins—includ ing block polymers and mechanical resin/mineral mixtures — a r e restricted to the region close to the lower curve. Engineering plastics cluster near the upper curve. But high-density polyethylene/mineral complexes (Loymer S, Loymer R) show a higher bending modulus than does· polypropylene, yet are significantly tougher. (Loymer R at upper left is a nylon 66/mineral complex.) Their heat distortion temperatures are also higher than those of polyolefins alone. High-performance Loymer grades can provide a modulus equal to that of aluminum with the tough ness of nylon or polyethylene. General-purpose grades pose no incineration problem, because their heat of com bustion is comparable to that of wood or paper and they produce no toxic gases when burned.
