THE WIDENING HORIZON OF PLASTICS Wider acceptance, based on pe formance, points to a 7-billion-pound market for plastics as material of
construction by
7970. Present annual
consumption is ouer 7 billion pounds, or about 20% o f the total market RA
Y
M 0N D B . S
Ey M0u R
n spite of competition both within the industry and
I from producers of other materials of construction,
growth of the plastics industry continues. Since inherent advantages and disadvantages of specific plastic products have been recognized by both producer and consumer, misapplications are now less frequent. Current performance records compare favorably with those of more conventional materials of construction. The present per capita consumption of plastics ranges from 36 and 34 pounds in West Germany and U.S.A., respectively, to 17 and 13 pounds in France and Italy. I t is expected that over 50 pounds of plastics per capita will be consumed annually in this nation by 1975. Many important trends in individual plastic materials are masked by the continued growth of the “billion pound plastics.” Much of the future growth of polyolefins, polymers of vinyl chloride and styrene polymers, will be influenced by price considerations. Few materials of construction can compete with these billion pound plastics on a cost per unit volume basis. I n contrast, many of the engineering plastics will become “multimillion dollar plastics,” because of unique performance potentials as functional materials. Over 1 billion pounds of plastics are consumed annually as materials of construction in U.S.A. Wider acceptance based on unprecedented performance assures an annual consumption of over 7 billion pounds for this important end use in 1970. Applications for neutron shielding in nuclear power planls, thermal insulation, and corrosion resistance will account for large tonnage of these products. However, applications such as multicolored pavements or expendable structures may require ever larger amounts of plastic materials in the near future. Design and Engineering
A Rigid Container Division has been formed by the Society of Plastics Industry. Comparative cost data for plastic tanks have been published ( 3 A ) . Large con-
tainers and ducts have been fabricated by blow-molding techniques. Containers and intricately designed items have also been produced by powder molding of pulverized thermoplastics. This technique and polymerization of monomers in situ have reduced both mold costs and size limitations considerably. Pillow tanks in sizes u p to 1000-gallon capacity serve as satisfactory storage vessels. Such tanks require little storage space when collapsed. An empty pillow tank with a capacity of 75,000 gallons can be stored in a 13 X 4 foot box. Riveted metal containers are being made liquid-tight by the application of metal filled epoxy resin cement. Even the conventional wooden cooling tower is being replaced by modern materials of construction. Cellular plastics are used in place of insulating cork and large plastic grids are used in the tower construction ( 2 A ) . These units, measuring 82 X 46 X 12 inches, are said to be the largest injection-molded parts produced to date. Plastic column packing of conventional and unusual shapes have gained wide acceptance because of their light weight and inherent resistance to corrosives. Spaghetti-like strands of cellular plastics have also been used for this application. All-plastic scrubbers have proved to be unusually satisfactory in the control of air pollution ( I A ) . Reinforced Plastic Structures
Over 1 1 / 2 million miles of glass thread was used in the construction of the successful filament-wound rocket casing. This type of construction has increased the range of the Polaris missile without changing the size of the casing. Design information on the construction of a 17-foot fuel tank for orbital vessels has been supplied (6B). About 300 million pounds of reinforced plastics are being consumed annually in construction, transportation, boats, missiles, and other applications. This broad base of use assures a continuation of the healthy growth of this industry. (Continued on next page) VOL 54
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Refractory-filled phenylsilanes are satisfactory as ablative coatings The body of the Studebaker Avanti like that of the Corvette is constructed of reinforced plastics. Replacement automobile fenders, ladders, and reeds for musical instruments are based on similar materials. Improved properties may be obtained when specific procedures are used in the preparation of reinforced plastics (2%). The success story of this phase of the plastics industry has stimulated additional interest in the use of other fillers (77B). A new glass fiber which retains its strength at high temperatures has been developed. T h e addition of flake glass to plastics has improved reiistance to moisture ( I Z B ) . Mica paper has been used to prepare strong laminates (4B). Investigation of fillers has revealed a definite interaction between polymers and specific fillers. Active fillers have been produced by special surface treatment. A review of properties of metal-filled plastics has been published (3B). The heat resistance, strength, and dimensional stability of thermoplastics (8B) have been improved by the addition of mineral fillers. Information is available on simplified stress analysis of reinforced plastic pressure vessels ( 7 B ) . Service life can now be estimated (7B, 9B) and ultrasonics may be employed for nondestructive testing of reinforced plastic structures ( 5 B ) . Proper selection of resins has assured the correct design of large structures for service in corrosive environments ( I 3 B ) . Studies on immersed specimens have shown that most of the reduction in the elastic modulus of reinforced plastics occurs during the first 10 days of service (70B).
lack of quantitative results and absence of a temperature gradient which exists in actual service. Test procedures kvhich overcome these objections have been developed by Du Pont and Atlas corrosion engineers. Data from these cells or from total immersion tests may be used with flexural strength and flexural modulus tests ( I D , 3 0 ) . Reports demonstrating the versatility of plastics as corrosion-resistant materials have been published (20). Such reports and comparable information on performance of plastic structures in corrosive environment have reassured corrosion engineers of the effectiveness of properly selected plastics in the battle against corrosion. Sheet and Film
Linear polyester film has been used successfully for outer space exploration and as a temporary support in the construction of buildings. Exceedingly thin (15-gage) polyester film is now available commercially. Film with superior electrical and chemical properties has been produced by the condensation of 1,dr-cyclohexane dimethanol and terephthalic acid ( 2 E ) . Plastic film has performed satisfactorily as a heat exchanger. Heat-resistant sheeting has been obtained by vacuum deposition of gold on polytetrafluoroethylene film. Fabric coated with fluorocarbon elastomers has been used for making corrosive-resistant clothing. Pressure sensitive poly(viny1 chloride) tapes are used for wrapping underground pipe. One of the largest uses of this type film is for the production of three-ply laminated foam sheeting (YE). Extruded polystyrene foamed sheet has replaced paper and other types of sheeting in numerous applications.
Plastics vs. Temperature Coatings and Linings
Half-life values which provide a better understanding of degradation mechanism have been obtained by plotting weight loss of plastics at high temperatures (5C). Polyphenylene sulfides, polymers containing triazine rings, polybenzimidazoles. and inorganic polymers have shown promise for high temperature applications ( Z C , 4C). Refractory-filled phenylsilanes were satisfactory as ablative coatings at 3000" F. Additional information on composites for ablative and thermal insulation on hypersonic vehicles has been provided (3C). Papers presented at an ASTM symposium on high temperature applications of plastics are now available in book form ( 7 C ) . Plastics vs Corrosion
The rate of degradation of plastics under service conditions may be determined by the use of ultrasonics ( 4 0 ) or by the use of a portable instrument which determines changes in flexural modulus. These nondestructive tests help anticipate failures and permit addition of reinforcements and patches when indicated. Some of the principal objections to coupon testing are 54
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
The length of service for the many successful installations of pipe lined with Saran (vinylidene chloride copolpmer) has catalyzed the use of more resistant plastics for the same application. Metal pipe is being lined with Penton (polyoxetane) using both extrusion and powdered resin techniques. The fluidized resin technique has also been used to coat filter plates, valves, pumps, and other process equipment. An electrostatic field may be used instead of a hot surface for attracting the powdered resin particles. Since the charge powder is preferably attracted to bare spots and thinly coated areas, it is said to provide a more uniform surface. Both techniques require post heat fusion. Portable guns are available for heat-spraying thermosetting plastics. AUTHOR Dr. Raymond B . Seymour is Chairman, Chemistry D e p t . , S u l ROSSState College, Alpine, Tex. H e returned t o academic l i f e after an extensive industrial career. Recijient of the Western Plastics A w a r d in 1960, he has authored I&EC's Plastics review since 1950. T h i s re$ort x a s prepared w i t h the assistance of F. I. S m i t h .
Plasma-arc guns have also been used for the application of engineering plastics. The plasma-arc gun has been modified for temperatures below 3000" F. No oven fusion is required. I t is expected that over 8 million gallons of polyurethane coatings will be used annually in 1965. Latices based on acrylics, butyl rubber, and styrene butadiene copolymer are serving successfully as coatings for paperboard. Almost 50 million gallons of these products were consumed during the past year, and this quantity is expected to double by 1965. Plastic Pipe
About 500 million feet of plastic pipe is being produced annually by 40 American firms. The almost universal acceptance of quality plastic pipe is based, to a large extent, on cooperation between consumer and supplier. I n this relationship, specifications rather than price were stressed (ZF,4F, 5F). Temperature limitations of polyethylene pipe have been reduced by the incorporation of carbon and organic peroxides. A portable machine for buttwelding thermoplastic pipe is available. Such pipe may also be joined through use of simple tools ( 7 F ) , Penton cladding is heat-fused onto standard metal pipe in the Whirlclad coating system. Cladding is 0.030 inch thick and provides uniform protection f o r conveyance systems carrying corrosive fluids or slurries coumEsY.
rm
POLYMER CORP
ultrasonics (gF), and neutron irradiation. The objection to either flammability or smoke production of burning plastic pipe has been overcome by the application of a thin coat of plaster after installation ( 3 F ) . Development of long term working-stress data for thermoplastic pipe has been described (7F). The strength of linear polyethylene pipe has been increased by orientation a t high temperatures (8F). Shrinkable tubing has been obtained by irradiating PVC pipe. Heat-shrinkable linear polyester pipe is also available. Many of the engineering plastics are being applied as linings by use of several different solvent-free processes. Poly(viny1idene fluoride) pipe is said to be satisfactory for a temperature range of -80" to 300" F. New information on comparative costs of plastic pipe has been published ( S F ) . Molded plastic threaded plugs are being used to prevent damage of metal pipe during shipment and storage. Acetal pipe has proved to be satisfactory for oil field service. Reinforced polyester pipe is being used for transporting chlorine dioxide a t 200" F. and 100 p.s.i. Equipment is available for on-site production of continuous lengths of reinforced plastic pipe. Reinforced pipe is now produced by centrifugal coating, mandrel wrapping, and continuous filament winding. Cellular Plastics
Interest in nonflexible foams is increasing. I t has been predicted that rigid foams will account for over 60% of the 600 million pounds of cellular plastics to be produced in 1966 (9G). This estimate may prove to be conservative if sprayed cellular plastics are accepted as a safety measure for coating walls in mines and other hazardous areas. Polyurethane foams may be produced by continuous methods ( 7 7G). New information has been supplied on one-shot formulations (7G) and frothing techniques used in the production of rigid forms of this type (5G). Processing techniques have been reviewed (ZG, 3G) and the relationship of thermal conductivity and structure has been investigated (4G). Information on the use of infrared and dielectric analysis of cellular plastics has been supplied (7G, 8G). SPI has established a urethane institute. Flame-resistant agents have been incorporated in injection moldable expandable polystyrene beads ( 72G). The relative advantages of inert gases and blowing agents in foam production have been discussed (6G). Because of inherent high strength and good electrical properties, polypropylene has found acceptance as a lightweight quality coating. Foamable powdered epoxy resin is tough and economical; it should find a definite place in the cellular plastics market (TOG). Plastic Materials
Polyolefins. The erection of new and improved facilities for the production of polyolefins is ample evidence of the future confidence in this phase of the plastics industry. Over 1.5 billion pounds of polyVOL. 5 4
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ethylene was sold in the U.S.A. in 1961. Low selling price has encouraged increased consumption of generalpurpose polymers and has also stimulated efforts toward development of higher priced specialty resins. High molecular weight polyethylene, copolymers, and graft and block polymers as well as modified polymers are available. Some improved products are made by the use of nelv catalysts which activate specific positions (76H). Others are copolymers of ethylene with butene, propylene, ethyl acrylate, or vinyl acetate. Ethylene-propylene copolymers are elastic and may he cured with sulfur (5H, 7H).Blends of copolymers or graft polymers with polymers of ethylene or propylene have distinct physical properties. Use of the ethylenebutene copolymer for packaging foods has been approved hy the U.S. Food and Drug Administration. Strong flexible bristles have been produced, using polypropylene monofilament as an encasement for oriented fibers. Modifications of polypropylene can compete with thermosetting resins in many applications. Polypropylene hot melts are available. -4superior lubricating grease has been produced by blending low molecular weight polyethylene and molybdenum disulfide. Properties and many applications of polypropylene have been reviewed ( 2 H ) . Vinyl Chloride Polymers. The unusual low price of less than 16 cents a pound for general purpose resin and the inherent good physical properties assure sound and continued growth of poly(viny1 chloride) plastics. Approximately 1 billion pounds of this type plastic was purchased in 1961. I n spite of its high specific gravity, PVC is replacing other materials where oil resistance and low cost are important. Loss of plasticizer from these products has lieen reduced by the addition of barium silicate. Plastisols which fuse at 300' F. and rigisols with low plasticizer content are available. The particle size of plastisol resin has been reduced by new spray-drying techniques, New data on outdoor durability of these plastics are available (123). Unusually- large selfextinguishing PVC building panels are now available. A new group of chlorinated resins of undisclosed composition has been introduced. Addition of chlorinated polyethylene has improved the flow of PVC. Selected compounding agents may be added to control the cross linking of vinyl chloride resins ( 7 4 H ) . A review on standards for this type plastic has been published (24H). Styrene Polymers. Monomer production capacity of 3 billion pounds, low specific gravity, good performance records, and low selling price have strengthened the position of polystyrene plastics in the billion pound club. Price reductions to 25 cents a pound have stixnulated interest in styrene-acrylonitrile copolymer, now made a t an annual rate of 25 million pounds. Interest in ABS (acrylonitrile-butadiene-styrene) as an engineering plastic continues ( I I H ) . However, the general purpose product accounts for the bulk of production of styrene plastics (27H). Polyff uorocarbons. The availability of fluorosili56
INDUSTRIAL A N D ENGINEERING CHEMISTRY
cones and new copolymers of tetrafluoroethylene (6") or vinylidene fluoride have aided the materials engineer in the solution of many problems. Fluorocarbon monomers may be produced by the pyrolysis of trifluoromethane or monochlorodifluoroethylene. Controlled cooling renders the polymers transparent. Inherent resistance to chemicals and heat, characteristic lubricity, and antistick properties as well as price reductions have assured the growth of fluorocarbon resins. This growth will continue in spite of unproved rumors of toxicity of the hot resin. Resistance to abrasion and deformation has been increased by the addition of colloidal boehmite. The addition of polyfluorocarbons to other therrnoplastics has produced materials with low frictional coefficients. Antistick surfaces can be formed by heat sealing polyfluorocarbon film to other materials. A wide variety of monofilaments and screenlike materials have been produced from polyfluorocarbons. Tape made from this type of plastic is used to seal threaded pipe and prevent electrolytic corrosion. Piston rings of this plastic have been used in compressors for organic vapors. Unusually larg-e billets and laminates have also been fabricated. Linear Polyesters. The tensile strength of linear polyesters has been improved by grafting of styrene in the presence of cobalt-60. Springs which retain their high tensile strength a t low temperatures have been fabricated from polyester plastics. Copolymers of 2-methylstyrene and methyl methacrylate have improved resistance to water and chemicals. Polybenzylmethacrylate with a high coefficient of optical sensitivity and flexible acrylate sheets arc available. Polymethylmethacrylate glazing has been approved for use in building construction. Polyamides. A new high melting nylon polymer with superior chemical resistance has been announced. Many new polyamides have been produced but their slight superiority over Nylons 6, 66, 610, and 11 is not sufficient to warrant their manufacture ( 7 H ) . Processing properties have been improved by blending Kylon 6 with Nylon 66 (25H). Blends of polypropylene and nylon are available. Large structural parts have been made by polymerizing caprolactam in situ. Miscellaneous Thermoplastics. Properties of acetal ( 3 H ) and polycarbonate resins (70H) have lieen reviewed. The latter is resistant to gamma radiation (75H). Superior properties have been noted when groups have been grafted on silicone polymers. Products prepared by grafting styrene on cellulose and its derivatives contain much unreacted cellulose and polystyrene. Free radicals produced by the radiation of many different polymers have been stabilized. Epoxy Resins. Addition of powdered fillers to epoxy resins decreases shrinkage and alleviates the exotherm during cure. Fibrous fillers improve impact strength of these resins ( 4 H ) . Filled epoxy compositions are being used as adhesives for setting bolts in concrete, brick mortar, road surfacing, and patching cement for chemical processing equipment.
Stable one-can epoxy resin systems and heat curable pellets are now available. Flexible resins have been produced by the addition of aliphatic glycol diglycidyl ether (78H). Products with superior resistance to elevated temperatures are also available. Thermosetting Polyester Resins. Superior polyester plastics have been produced by the use of multiple catalyst systems ( 7 7 H ) , and by the replacement of maleic acid by fumaric acid (23H) or the replacement of phthalic acid by tetrahydrophthalic acid. Modifications with dipentene ( 6 H ) and bisphenol ( 79H) have improved adhesion and chemical resistance of this type resin. Miscellaneous. Dark colored flexible products have been prepared by the internal plasticization of phenolic resins (SH, 73H). Phenolic laminates with excellent heat resistance are available (2OH). Almost 150 million pounds of melamine resins were produced in 1961. I t is expected that over 200 million pounds of this type of resin will be produced in 1965. Flexible furan resins have been produced by the polymerization of furfuryl alcohol in the presence of polyfunctional amines (22H). One large development project on polymers of phosphonitrilic chloride has been abandoned, but interest in all types of inorganic polymers continues, Additional effort in this direction should overcome one of the few remaining objections to plastics-lack of resistance to high temperature. LITERATURE CITED
Plastics US. Corrosion
(1D) Cass, R. A., Fenner, 0. H., 18th Annual Conf., Natl. Assoc. of Corrosion Engrs., Kansas City, Mo., March 28, 1962. (2D) Fenner, 0. H., Chem. Eng. 69, No. 6, 200 (1962). (3D) Feuer, S. S., Plastics World 19, No. 6, 38 (1961). (4D) Hastings, C. H., LoPilato, S. A., Lynnworth, L. C., J . SOC. Non-Destructive Testing 19, No. 5 (Sept.-Oct. 1961). Sheet a n d Film (IE) Roggi, P. E., Western Plasitcs 9, No. 2, 35 (1962). (2E) Watson, M. T., S P E Journal 17, 1082 (1961). Plastic Pipe (1F) Berman, R . W., Rubber and P 1 a . k Age 42, 947 (1961). (2F) Darden, E. T., 19th Conf. Western Sect. SPI, Coronado, Calif., April 6, 1962. (3F) Freidrich, M., Heinricks, R. R., Kunststof51 (3), 126 (1961). (4F) La Follete, J. H., 19th Conf. of Western Sect. SPI, Coronado, Calif., April 6, 1962. (5F) Look, E. H., Plastics Technol. 7, No. 10, 35 (1961). (6F) Mendel, O., Chem. Eng. 68, No. 10, 190 (1961). (7F) Reinhart, F. W., S P E Journal 17, 751 (1961). (8F) Richard, K., Diedrich, G., Gaube, E., Plastics 26, No. 90, 111 (1961). (9F) Scarpa, T. J., Plastics Technol. 8 , No. 1, 22 (1962). Cellular Plastics (1G) Axelbrood, S. L., Hamilton, C. W., Frisch, T. C., IND.ENG. CHEM.53, 898 (1961). (2G) Dworkin, D., S P E Journal 17, 1269 (1961). (3G) Galloway, E. C., Chem. Eng. Progr. 57, No. 10, 35 (1961). (4G) Harding, R. H., James, B. R., Modern Plastics 39, No. 7, 133 (1962). (5G) Knox, R. E., Chem. Eng. Progr. 57, No. 10, 40 (1961). (6G) Meyer, R. J., Zbid., 57, No. 11, 66 (1961). (7G) Murphy, E. B., O’Neil, W. A., S P E Journal 18, 191 (1962). (8G) Skochdopole, R. E., Chem. Eng. Progr. 57, No. 10, 55 (1961). (9G) Tallman, J. C., Ibid., 57, No. 10, 52 (1961). (10G) Toohy, R . P., Zbid., 57, No. 10, 52 (1961). (11G) Wall, J. R., Ibid., 57, No. 10, 48 (1961). (12G) Zielinsky, A. R., Plastics World 20, No. 1, 18 (1962).
Design a n d Engineering (1A) Arndt, F. W., Chem. Eng. 68, No. 24, 146 (1961). (2A) Krueger, H . R., Plastics World 19, No. 12, 28 (1962). (3A) Krusen, G. C., Chem. Eng. 68, No. 18, 158 (1961). Reinforced Plastic Structures (IB) Brown, R . J., S P E Journal 17, 989 (1961). (2B) Calderwood, R. H., Hovanec, A. V., Plastics Technol. 8, No. 4, 38 (1962). (3B) Delmonte, J., “Metal Filled Plastics,” Reinhold, New York, 1961. (4B) Dinman, E. G., S P E Journal 17, 981 (1961). (5B) Hand, W., Plastics Technol. 8 , No. 2, 35 (1962). (6B) Lemons, R. C., Western Plastics 9, No. 1, 29 (1962). (7B) Loveless, H. S., Deeley, C. W., Swanson, D. L., SPE Transactions, 126, April (1962). (8B) Modern Plastics 39, No. 7, 98 (1962). (9B) Molt, R . P., S P E Journal 17, 977 (1961). (10B) Panferrov, K . V., Ramanennov, I. G., Soviet Plastics 11, 27 (1961). (11B) S P E Journal 18, 599 (1962). (12B) Suffredini, L. P., Materials for Design Eng. 54, No. 4, 95 (1961). (13B) Webster, R. M., Chem. Eng. 68, No. 13, 154 (1961). Plastics US. Temperature (1C) ASTM Reinforced Plastics for Rockets and Aircraft STP 279, 1961. (2C) Brenner, W., Lum, D., Riley, M. W., “High Temperature Plastics,” Reinhold, New York, 1962. (3C) Cotten, F. M., 19th Annual Conf., Western Sect. SPI, Coronado, Calif., April 5, 1962. (4C) Levine, H. H., IND.ENG.CHEM.54, 22 (1962). (5C) Madorsky, S. L., SPE Journal 17, 665 (1961).
Plastic Materials (1H) Aelon, R., IND.ENG.CHEM.53, 826 (1961). (2H) Ahmad, A. S., Glovier, R., Plastics World 20, No. 1, 12 (1962). (3H) Akin, R. B., “Acetal Resins,” Reinhold, New York, 1962. (4H) Akins, D., Forester, R., Holtby, F., Rubber and Plastics Age 42, 1086 (1961). (5H) Amberg, L. O., Robinson, A. E., Zbid., p . 875. (6H) Amidon, R. E., Johnston, R . M., others, S P E Journal 17, 1088 (1961) (7H) Bonotto, S., Krewsky, B. H., SPE Journal 18, 555 (1961). (8H) Bowers, G. H., Lovejoy, E. R., IND.ENG.CHEM.,Product Res. and Develop. I, No. 2, 89 (1962). (9H) Brooks, W. R., IND.END.CHEM. 53, 570 (1961). (10H) Christopher, W. F., Fox, D. W., “Polycarbonates,” Reinhold, New York, 1962. (11H) Coughlin, W. J., S P E Journal 18, 327 (1962). (12H) Darby, J . R., Graham, P. R., Modern Plastics 39, No. 5, 148 (1960). (13H) Freeman, J. H., Traymor, E. J., IND.ENG. CHEM.53, 570 (1961). (14H) Fuchsman, C. H., S F E Journal 17, 590 (1961). (15H) Giberson, R. C., Modern Plastics 39, No. 8, 143 (1962). (16H) Guccione, E., Chem. Eng. 69, No. 7, 93 (1962). (17H) Harrison, J. B., Mogeli, 0. L., others, Modern Plastics 39, No. 5, 135 (1962). (18H) Helmreich, R. F., Harry, L. O., S P E Journal 17, 583 (1962). (19H) Lietheiser, R. H., Dallinge, M., Modern Plastics 39, No. 9, 163 (1962). (20H) Miglarese, J., Plastics World 19, No. 6, 44 (1961). (21H) Modern Plastics 39, No. 8, 82 (1962). (22H) Nielsen, E. R., S P E Journal 17, 678 (1961). (23H) Park, R. E., Johnston, R . M., others, Zbid., 39, No. 5, 135 (1962). (24H) Reinhart, F. W., Zbid., 18, 308 (1962). (25H) Waltersperger, H., Kunststof Rundschau 8 , 265 (1961). VOL.54
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