Matar Sami, Hatch Lewis F. Chemistry of petrochemical processes

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Other Nylon Polymers

Many other nylons could be produced such as nylon nylon 5, nylon 7,

nylon 610, and nylon 612. These have properties generally similar to

those nylons described. Table 12-7 shows the monomers used to produce

important nylons and their melting points.

Synthetic Petroleum-Based Polymers 367

Table 12-7

Melting points of various nylons and the monomer formula

Chapter 12 1/22/01 11:12 AM Page 367

Properties and Uses of Nylons

Nylons are generally characterized by relatively high melting points

due to the presence of the amide linkage. They are also highly crystalline,

and the degree of crystallinity depends upon factors such as the polymer

structure and the distance between the amide linkages. An increase in

polymer crystallinity increases its tensile strength, abrasion resistance,

and modulus of elasticity.

Hydrogen bonding in polyamides is fairly strong and has a pronounced

etfect on the physical properties of the polymer such as the crystallinity,

melting point, and water absorption. For example, nylon 6, with six car-

bons, has a melting point of 223°C, while it is only 190°C for nylon 11.

This reflects the higher hydrogen bonding in nylon 6 than in nylon 11.

Moisture absorption of nylons differs according to the distance

between the amide groups. For example, nylon 4 has a higher moisture

absorption than most other nylons, and it is approximately similar to that

of cotton. This is a result of the higher hydrophilic character of nylon 4.

Nylons, however, are to some extent subject to deterioration by light.

This has been explained on the basis of chain breaking and crosslinking.

Nylons are liable to attack by mineral acids but are resistant to alkalies.

They are difficult to ignite and are self-extinguishing.

In general, most nylons have remarkably similar properties, and the

preference of using one nylon over the other is usually dictated by eco-

nomic considerations except for specialized uses.

Nylons have a variety of uses ranging from tire cord to carpet to

hosiery. The most important application is cord followed by apparel.

Nylon staple and filaments are extensively used in the carpet industry.

Nylon fiber is also used for a variety of other articles such as seat belts,

monofilament finishes, and knitwear. Because of its high tenacity and

elasticity, it is a valuable fiber for ropes, parachutes, and underwear.

The 1997 U.S. production of nylon fibers was approximately 2.9 bil-

lion pounds.

ACRYLIC AND MODACRYLIC FIBERS

Acrylic fibers are a major synthetic fiber class developed about the

same time as polyesters. Modacrylic fibers are copolymers containing

between 35–85% acrylonitrile. Acrylic fibers contain at least 85% acry-

lonitrile. Orlon is an acrylic fiber developed by DuPont in 1949; Dynel

is a modacrylic fiber developed by Union Carbide in 1951.

368 Chemistry of Petrochemical Processes

Chapter 12 1/22/01 11:12 AM Page 368

Polyacrylics are produced by copolymerizing acrylonitrile with other

monomers such as vinyl acetate, vinyl chloride, and acrylamide. Solution

polymerization may be used where water is the solvent in the presence of

a redox catalyst. Free radical or anionic initiators may also be used. The

produced polymer is insoluble in water and precipitates. Precipitation

polymerization, whether self nucleation or aggregate nucleation, has

been reviewed by Juba.

The following equation is for an acrylonitrile

polymer initiated by a free radical:

Synthetic Petroleum-Based Polymers 369

Copolymers of acrylonitrile are sensitive to heat, and melt spinning is not

used. Solution spinning (wet or dry) is the preferred process where a

polar solvent such as dimethyl formamide is used. In dry spinning the

solvent is evaporated and recovered.

Dynel, a modacrylic fiber, is produced by copolymerizing vinyl chlo-

ride with acrylonitrile. Solution spinning is also used where the polymer

is dissolved in a solvent such as acetone. After the solvent is evaporated,

the fibers are washed and subjected to stretching, which extends the fiber

4–10 times of the original length.

Properties and Uses of Polyacrylics

Acrylic fibers are characterized by having properties similar to wool

and have replaced wool in many markets such as blankets, carpets, and

sweaters. Important properties of acrylics are resistance to solvents and

sunlight, resistance to creasing, and quick drying.

Acrylic fiber breaking strength ranges between 22,000 and 39,000 psi

and they have a water absorption of approximately 5%. Dynel, due to the

presence of chlorine, is less flammable than many other synthetic fibers.

Major uses of acrylic fibers are woven and knitted clothing fabrics (for

apparel), carpets, and upholstery.

CARBON FIBERS (Graphite Fibers)

Carbon fibers are special reinforcement types having a carbon content

of 92–99 wt%. They are prepared by controlled pyrolysis of organic

materials in fibrous forms at temperatures ranging from 1,000–3,000°C.

Chapter 12 1/22/01 11:12 AM Page 369

The commercial fibers are produced from rayon, polyacrylonitrile, and

petroleum pitch. When acrylonitrile is heated in air at moderate temper-

atures (≈ 220°C ), HCN is lost, and a ladder polymer is thought to be

the intermediate:

370 Chemistry of Petrochemical Processes

Further heating above 1700°C in the presence of nitrogen for a period of

24 hours produces carbon fiber. Carbon fibers are characterized by high

strength, stiffness, low thermal expansion, and thermal and electrical

conductivity, which makes them an attractive substitute for various met-

als and alloys.

These fibers have longitudinal tensile strengths and

moduli ranging from 2.5–7.0 GPa and 230–590 GPa, respectively. A

bending beam force detector was developed to measure longitudinal

compressive strengths of polyacrylonitrile-based carbon fibers.

Most carbon fiber composites are based mainly on thermosetting

epoxy matrices.

Current U.S. production of carbon fibers is approximately ten million

pounds/year.

POLYPROPYLENE FIBERS

Polypropylene fibers represent a small percent of the total polypropy-

lene production. (Most polypropylene is used as a thermoplastic.) The

fibers are usually manufactured from isotactic polypropylene.

Important characteristics of polypropylene are high abrasion resist-

ance, strength, low static buildup, and resistance to chemicals.

Crystallinity of fiber-grade polypropylene is moderate and when heated,

it starts to soften at approximately 145°C and then melts at 170°C. The

physical properties of fiber-grade polypropylene are given in Table 12-8.

Melt spinning is normally used to produce the fibers.

The high MP of

polypropylene is attributed to low entropy of fusion arising from stiffen-

ing of the chain.

Polypropylene fibers are used for face pile of needle felt, tufted car-

pets, upholstery fabrics, etc.

The total 1997 U.S. production of polyolefin fibers, including

polypropylene fibers, was approximately 2.5 billion pounds.

Chapter 12 1/22/01 11:12 AM Page 370

REFERENCES

1. Wittcoff, H. A. “Polymers in Pursuit of Strength,” CHEMTECH, Vol.

17, No. 3, 1987, pp. 156–166.

2. Chemical Week, No. 14, 1984, p. 13.

3. Hatch, L. F. and Matar, S., From Hydrocarbons to Petrochemicals,

Gulf Publishing Co., Houston, 1981, p. 171.

4. Bennet, A., CHEMTECH, Vol. 29, No. 7, 1999, pp. 24–28.

5. El-Khadi, M. and David, O. F., Second Arab Conference on Petro-

chemicals, United Arab Emirates, Abu Dhabi, March 15–22, 1976.

6. Sittig, M., “Polyolefin Production Processes,” Chemical Technology

Review No. 79, New Jersey, Noyes Data Corp., 1976, p. 9.

7. “Petrochemical Handbook,” Hydrocarbon Processing, Vol. 70, No. 3,

199l, p. 173.

8. Sinclair, K. B., “For Polyolefins: Estimate Gas Phase Production

Costs,” Hydrocarbon Processing, Vol. 64, No. 7, 1985, pp. 81–83.

9. Newton, D., Chinh, J. C., and Power, M., “Optimize Gas-phase

Polyethylene,” Hydrocarbon Processing, Vol. 77, 1998, pp. 85–91.

10. Chemical and Engineering News, June 29, 1998, p. 44

l1. Sacks, W., “Packaging Containers,” CHEMTECH, Vol. 18, No. 8,

August 1988, pp. 480–483.

12. Modern Plastics, Vol . 52, No. 6, 1975, p. 6.

13. Chemical and Engineering News, March 30, 1992, p. 17.

14. “Petrochemical Handbook,” Hydrocarbon Processing, Vol. 70, No. 3,

1991, p. 176.

Synthetic Petroleum-Based Polymers 371

Table 12-8

Physical properties of fiber-grade polypropylene

Fiber-grade Fiber-grade

Property homopolymer copolymer

Specific gravity at 23°C 0.905–0.910 0.895–0.905

Flow rate at 230°C, 2160 g load g/10 min 6 3

Tensile yield at 2 in./min psi 5000 4000

Stiffness in flexure 10

psi 190 150

Unnotched izod, impact at 0°F-ft-lb/in. <10 >20

Melting point, dilatometer °C 172 170

Water adsorption, 24 hr. % <0.01 <0.01

Environmental stress cracking % failure none none

Chapter 12 1/22/01 11:12 AM Page 371

15. Chemical and Engineering News, Jan. 16, 1995, pp. 6–7.

16. Golab, J. T., “Making Industrial Decisions with Combutational

Chemistry,” CHEMTECH, Vol. 28, No. 4, 1998, pp. 17–21.

17. Hydrocarbon Processing, Vol. 77, No. 11, 1998, p. 25

18. Rodriguez, F., Principles of Polymer Systems, 3rd Ed., Hemisphere

Publishing Corp., New York, 1989, p. 466.

19. “Petrochemical Handbook,” Hydrocarbon Processing, Vol. 70, No. 3,

1991, p. 180.

20. Ainsworth, S. J., “Plastics Additives,” Chemical and Engineering

News, August 31, 1992, pp. 34–39.

21. Kix, M. et al., Polymer Bulletin, Vol. 41, 1998, pp. 349–354.

22. Hydrocarbon Processing, Vol. 77, No. 9, 1998, p. 11

23. Hydrocarbon Processing, Vol. 70, No. 12, 1991, p. 29.

24. Piccolini, R. and Plotkin, J., “Patent Watch,” CHEMTECH, Vol. 29,

No. 3, 1999, p. 31.

25. Sikdar, S. K., “The World of Polycarbonates,” CHEMTECH, Vol. 17,

No. 2, 1987, pp. 112–117.

26. Leslie, V. J., Rose, J., Rudkin, G. O., and Fitzin, J. CHEMTECH,

Vol. 5, No. 5, 1975, pp. 426–432.

27. Guide to Plastics, New York, McGraw Hill, Inc., 1976.

28. Modern Plastics International, Vol. 9, No. 4, 1979, p. 8–10.

29. Kennedy, J. P., “Polyurethanes Based on Polyisobutylenes,”

CHEMTECH, Vol. 16, No.11, 1986, pp. 694–697.

30. Baekeland, L. H., The Journal of Industrial and Engineering

Chemistry, March 1909; CHEMTECH, Vol. 6, No. 11, 1979,

pp. 40–53.

31. Chemical Engineering, Sept. 15, 1975, p. 106.

32. Stinson, S. “Polycyanurates Find Applications, Their Chemistry

Remains Puzzling,” Chemical and Engineering News, Sept. 12, 1994,

pp. 30–31.

33. Hall, D. and Allen, E., Chemistry, Vol. 45, No. 6, 1972, pp. 6–12.

34. Coran, A. Y., CHEMTECH, Vol. 13, No. 2, 1983, p. 106.

35. Hertz, D. L., Jr., “Curing Rubber,” CHEMTECH, Vol. 16, No. 7, 1986,

pp. 444–447.

36. Reisch M. S., “Thermoplastic, Elastomers Bring New Vigor to

Rubber Industry,” Chemical and Engineering News, May 4, 1992, pp.

29–41.

37. Stevens, M. P., Polymer Chemistry, Addison Wesley Publishing Co.

London, 1975, p. 156.

38. Natta, G. J., J. Polymer Science, Vol. 48, 1960, p. 219.

372 Chemistry of Petrochemical Processes

Chapter 12 1/22/01 11:12 AM Page 372

39. British Patent 848,065 to Phillips Petroleum Co., April 16, 1956.

40. Platzer, N., CHEMTECH, Vol. 9, No.1, 1979, pp. 16–20.

41. Jelinski, L. W., “NMR of Plastics,” CHEMTECH, Vol. 16, No. 5,

1986, pp. 312–317.

42. Platzer, N. CHEMTECH, Vol. 7, No. 8, 1977, p. 637.

43. “Petrochemical Handbook,” Hydrocarbon Processing, Vol. 54,

No. 11, 1975, p. 194.

44. Dall’Asta, G. Rubber Chemical Technology, Vol. 47, 1974, p. 511.

45. Holden, G., Condensed Encyclopedia of Polymer Science and

Engineering, John Wiley and Sons, 1990, pp. 296–297.

46. Chemical Industries Newsletter, Jan.–Mar., 1999, p. 12

47. “Petrochemical Handbook,” Hydrocarbon Processing, Vol. 56,

No. 11, 1977, p. 203.

48. Farrow, G. and Bagley, I., Texas Research Journal, Vol. 32, 1962,

p. 587.

49. Brown, A. E. and Reinhart, K. A., Science, Vol. 173, No. 3994, 1971,

p. 290.

50. “Petrochemical Handbook,” Hydrocarbon Processing, Vol. 78,

No. 3, 1999, p. 128.

51. Studiengesellschaft Kohle, German Patent, 1,075,610.

52. Hatch, L. F., Studies on Petrochemicals, New York, United Nations,

1966, pp. 511–522.

53. Juba, M. R., “ A Review of Mechanistic Considerations and Process

Design Parameters for Precipitation Polymerization,” in Polymeriza-

tion Reactions and Processes, ACS Symposium Series No. 104,

Washington D.C., 1979, pp. 267–279.

54. Riggs, P. R., Condensed Encyclopedia of Polymer Science and

Engineering, John Wiley and Sons, 1990, pp. 105–108.

55. Oya, N. and Johnson, J. “Direct Measurement of Longitudinal

Compressive Strength in Carbon Fibers,” Carbon, Vol. 37, No. 10,

1999, pp. 1539–1544.

56. Brownstein, E. E, International Seminar on Petrochemicals, October

25–30, 1975, Baghdad, Iraq.

Synthetic Petroleum-Based Polymers 373

Chapter 12 1/22/01 11:12 AM Page 373

APPENDIX ONE

Conversion Factors

To convert from To Multiply by

atmospheres mm of mercury 760

atmospheres pounds/sq. inch (psi) –14.696

barrels (oil) gallons (U.S.) –42

bars atmospheres ––0.98692

≈ mm of mercury (0°C) 750.062

≈ pascal ––l × 10

Btu calorie 252.15105

≈ joules ––1.055 × 10

calories gram (mean/gram) Btu (mean) pound ––1.8

calories Btu ––3.9658 × 10

–3

≈ joules ––4.1840

centimeters angstrom ––1 × 10

≈ feet ––0.0328

≈ inches ––0.3937

≈ meters ––0.01

≈ microns ––1 × 10

cubic feet (ft

) gallons (British) ––6.2288

≈ gallons (US) ––7.48052

≈ liters –28.317

cubic meters barrels (US, liquid) ––8.3865

≈ cubic feet (ft

) –35.314445

≈ gallons (US) 264.173

≈ liters 999.973

feet centimeters –30.48

gallons (U.S.) cubic feet (ft

) ––0.1336805

≈ liters ––3.78543

grams ounces (avdp.)* ––0.0352939

≈ ounces (troy) ––0.0321507

grams/sq. centimeter pounds/sq. foot ––2.04817

inches centimeters ––2.540005

kilograms pounds (avdp.)* ––2.20462234

≈ pounds (troy) ––2.6792285

liters gallons (British) ––0.219976

≈ gallons (U.S.) ––0.2641776

meters angstroms ––1 × 10

374

APP1 1/22/01 11:13 AM Page 374

To convert from To Multiply by

≈ inches ––39.37

pounds/sq. inch pressure kilopascal (kPa) –––6.8948

pounds (avdp.)* grams –453.59

≈ ounces (avdp.)* ––16

pounds (avdp.)* ounces (troy) ––14.5833

pounds (troy) ounces (troy) ––12

pounds/sq. inch grams/sq. centimeter ––70.307

tons (metric) kilograms 1000

≈ pounds (avdp.)* 2204.62

tons (short) pounds 2000

watts (abs) Btu (mean)/hour –––3.41304

*avdp. = avoirdupois

Temperature Conversion:

degree Celsius (°C) = (°F – 32) × 5/9

degree Fahrenheit (°F) = °C × 9/5 + 32

degree Kelvin (°K) = °C + 273

degree Rankine (°R) = °F + 460

Conversion Factors 375

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APPENDIX TWO

Selected Properties of

Hydrogen, Important C

-C

Paraffins, Methylcyclopentane

and Cyclohexane*

Properties

Hydrocarbon Sp.Gr. Boiling Freezing Heat of

20/4°C Point °C Point °C Combustion**

K. Cal./mol

Hydrogen 0.08988 g/l

‡

–252.8 –259.3 68.315

(0.0694)

‡‡

Methane 0.466

–164

–164 –182 212.79

Ethane 0.572

–100/4

–88.6 –183.3 372.81

(1.049)

‡‡

Propane 0.5853

–45/4

–42.1 –189.7 530.57

(1.562)

‡‡

2-Methylpropane 0.5631 –11.1 –159.8 683.4

(isobutane)

n-Butane 0.5788 –0.5 –138.4 —

2,2-Dimethylpropane 0.591 9.5 –16.5 —

(neopenane)

2-Methylbutane 0.6201 27.8 –843.5

(isopentane)

n-Pentane 0.6262 36.1 –130 845.16

2,2-Dimethylbutane 0.6485 49.7 –99.9 —

(neohexane)

2,3-Dimethylbutane 0.6616 58 –128.5 —

2-Methylpentane 0.6532 60.3 –153.7 —

3-Methylpentane 0.6645 63.3

n-Hexane 0.6603 69 –95 —

n-Heptane 0.6837 98.4 –90.6 1149.9 (liquid)

n-Octane 0.7026 125.7 –56.8 1302.7 (liquid)

n-Nonane 0.7176 150.8 –51 —

n-Decane 0.7300 174.1 –29.7 1610.2 (liquid)

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