1. Polymers (part I)

2. Polymer:
“a substance consisting of molecules characterized by the repetition (neglecting ends, branch junctions and other minor irregularities) of one or more types of monomeric units.” ASTM

3. FIGURE 6-10 Various polymer structures.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

4. Categorizing Polymers
Natural / Synthetic
Organic / Inorganic
Thermoplastic / Thermoset
Linear / Cross-linking
General Purpose / Engineering
Floating / Sinking
Toxic / Non-toxic
Chemical Makeup
Etc.

5. FIGURE 6-2 Industrial polymers.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

6. Plastic
“a material that contains as an essential ingredient one or more organic polymeric substances of large molecular weight, is solid in its finished state, and, at some stage in its manufacture or processing into finished articles, can be shaped by flow.” ASTM
A synthetic polymer

7. Plastics are:
“any one of a large and varied group of materials consisting wholly or in part of combinations of carbon with oxygen, hydrogen, nitrogen, and other organic or inorganic elements which while solid in its finished state, at some stage in manufacture is made liquid, and thus capable of being formed into various shapes, most usually through the application, either singly or together, of heat and pressure.” Society of Plastics Industry. (p.341)

8. Figure C-4 Color Polymer Stuff: products made of various plastics and elastomers demonstrate the wide ranges of colors, forms, and properties possible with synthetic polymers. Note the white and blue and white and black toothbrushes in the middle with flexible heads, contoured shape, and soft rubber dots and strips for gripping. What types of plastics and elastomers are shown here?
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

9. FIGURE 6-60 SPI’s voluntary plastic container coding system
FIGURE SPI’s voluntary plastic container coding system. (Dow Chemical)
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

10. FIGURE Plastic food containers—(a) tough and lightweight properties of plastics make them very competitive with glass and steel. The barrier plastic ketchup bottle on the left, made of layered composite plastics [see detail in b], weights 80% less than the glass catsup bottle on the right. The plastic container is less likely to break than the glass bottle and saves transportation costs. Why would one company choose glass and the other company plastic?
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

11. FIGURE 6-22 (b) Five layers of barrier plastic container.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

12. Resin
Solid or semisolid uncompounded ingredients or monomers that are mixed by not yet polymerized
(“Resin” is sometimes used in the trade to refer to bulk polymer materials, such as polyethylene pellets for injection molding.)

13. Monomer
“a low-molecular-weight substance consisting of molecules capable of reacting with like or unlike molecules to form a polymer.” ASTM

14. Homopolymers Have repeating units of a single mer
E.g., polyethylene, polystyrene

15. FIGURE 6-3 Types of polymers: (a) Simple polymer. (b) Homopolymers.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

16. Copolymers “contain two different types of monomers.”
E.g., “polyvinyl chloride mixed with vinyl acetate to produce polyvinyl acetate.”

17. Terpolymers “contain three types of monomers”
E.g., acrylonitrile butadiene styrene (ABS)

18. Isomers
“variations in the molecular structure of the same compositions.”

19. FIGURE 6-3 Types of polymers: (c) Copolymers. (d) Isomers.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

20. Polymerization
“a chemical reaction in which the molecules of monomers are linked together to form polymers.” ASTM
Types:
Addition
Condensation

21. Addition Polymerization
Or “Chain Reaction” polymerization
“By the use of heat and pressure in an autoclave ore reactor, double bonds of unsaturated monomers break loose and then link up into a chain.”

22. Addition Polymerization
Commonly: thermoplastics
Examples:
PP: Polypropylene
PE: Polyethylene
PVA: Poly(vinyl acetate)
PVC: Poly(vinly chloride)
ABS: Acrylonitrile butadiene styrene

23. Example: Polyethylene
Bifunctional Ethylene (C2H4)
Ethylene mer
Polyethylene

24. FIGURE 6-4 (a) Monomer of ethylene (C2H4)
FIGURE (a) Monomer of ethylene (C2H4). Carbon atoms with four valence electrons have four arms (shared electrons) for covalent bonding. Two shared electrons hold another carbon atom in a double bond. Two other shared electrons, each covalently bonded, hold one shared electron of hydrogen, which has only one valence electron for single bonds. Double bonds are not stable and form reactive sites. (b) Polyethylene, chain of ethylene monomers. During polymerizaton, heat and pressure break the hold of one shared electron on each of the double-bonded (reactive sites) carbon atoms, thereby leaving each carbon atom of the monomers free to grasp another carbon atom (covalent bond) from other ethylene monomers, which form into a chain of thousands of ethylene monomers (polyethylene). The single bonds satisfy the carbon bond arrangement and produce the most stable saturated polymers because they have no reactive sites.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

25. FIGURE 6-5 (a) Typical polymers produced through addition (chain) polymerization.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

26. FIGURE (b) A portion of a modern polymer processing plant showing some of the complex apparatus and piping necessary to produce resins.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

27. Condensation Polymerization
Aka: Step Reaction
“Polymerization in which monomers are linked together with the splitting off of water or other simple molecules.” ASTM

28. FIGURE 6-6 Graphical illustration of condensation (step) polymerization of a polyamide (nylon).
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

29. Condensation Polymerization
Thermoset Examples
PF: Phenolic
PET: Polyester
PUR: Polyurethane
SI: Silicone
Thermoplastic Examples
PC: Polycarbonate
PA: White Nylon

30. Molecular Weight of a Polymer
Polyethylene Molecule: [C2H4]n=2000
Using 12 for wt of C and 1 for wt of H:
Weight of C2H4 mer = (2x12) + (4x1) = 28
Molecular wt = 2000 x 28 = 56,000

31. Determine the Molecular Weight of:
Polypropylene with n = 1500
(Use Table 10-9)

32. Polypropylene C3H6 Mer weight = (3x12) + (6x1) Mer weight = 42
At n=1500, molecular weight = 63,000

33. Determine the Molecular Weight of:
Acrylic with n = 1600
(Use Table 10-9)

34. Acrylic CH2O Mer weight = 12 + (2x1) + 16 Mer weight = 30
At n=1600, molecular weight = 48,000

35. General Relationship Between Plastics’ Molecular Weight and Mechanical Properties

36. The Melting Point of Plastics Generally Increases with Molecular Weight

37. FIGURE 6-7 Degrees of crystalline structure of polymers
FIGURE Degrees of crystalline structure of polymers. (a) Mostly amorphous (b) Semicrystalline (crystallites encircled) (c) Mostly crystalline (d) Liquid crystal polymer (Luther Gammon, Boeing Materials Technology)
(a)
(b)
(c)
(d)
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

38. FIGURE 6-7 Degrees of crystalline structure of polymers
FIGURE Degrees of crystalline structure of polymers. (e) Ultra-thin section of transmitted, cross-polarized, light circles, polymer matrix composite—carbon fiber (cut at 90 and seen as black circles) in a matrix of PEEK thermoplastic with liquid-crystalline spheroids at 2000x/100x obj. (Luther Gammon, Boeing Materials Technology)
(d)
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

39. FIGURE 6-8 Polymers and crystallinity
FIGURE Polymers and crystallinity. (a) Properties: relation to molecular weight and crystallinity. (b) Effect of pulling an amorphous polymer through a die.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.

41. Vulcanization
“an irreversible process during which a rubber compound…becomes less plastic and more resistant to swelling by organic liquids and elastic properties are conferred…” ASTM
Typically, through the addition of sulfur

42. FIGURE 6-36 Vulcanized rubber. (a) Natural rubber—thermoplastic
FIGURE Vulcanized rubber. (a) Natural rubber—thermoplastic. (b) Vulcanized (cross-linked) rubber—thermoset.
James A. Jacobs & Thomas F. Kilduff Engineering Materials Technology, Fourth Edition
Copyright ©2001 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.