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Polymer Physics Overview Lecture 1

Polymer Physics Overview Lecture 1. Dr. Anthony Brennan University of Florida Department of Materials Science & Engineering. Agenda. Introduction Definitions Configurational States Structure/Property Relationships Polymer Classifications Molar Mass Distribution

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Polymer Physics Overview Lecture 1

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  1. Polymer PhysicsOverviewLecture 1 Dr. Anthony Brennan University of Florida Department of Materials Science & Engineering EMA 6165 Polymer Physics - Lecture 1

  2. Agenda • Introduction • Definitions • Configurational States • Structure/Property Relationships • Polymer Classifications • Molar Mass Distribution • Thermal Transitions (General) EMA 6165 Polymer Physics - Lecture 1

  3. Properties • Chemical • Physical • Electronic • Magnetic • Optical CERAMICS METALS PROPERTIES ELECTRONIC MATERIALS POLYMERS EMA 6165 Polymer Physics - Lecture 1

  4. Polymer monomer (repeat unit) oligomers Bond energies Reactions Condensation Polymerization Addition Polymerization Chain Growth Structure Thermoplastics Thermosets Elastomers Chain Structure Homopolymer Copolymer Branching Stereoregular Isomeric Molar Mass Number, Weight Ave Degree of polymerization (DP) Polydispersity Vocabulary EMA 6165 Polymer Physics - Lecture 1

  5. Polymer • macromolecules formed by combining large numbers of low molar mass molecules • molar mass exceeds 10 kg/mol for reasonable properties EMA 6165 Polymer Physics - Lecture 1

  6. linear chain homopolymer random copolymer branched chain homopolymer copolymer block copolymer AAAAABBBBB star polymer comb graft chain copolymer Polymer Chain Structure EMA 6165 Polymer Physics - Lecture 1

  7. homopolymer condensation AA + BB AB addition A copolymer random alternating block graft Polymer Chain Composition EMA 6165 Polymer Physics - Lecture 1

  8. General Classification of Polymers • Thermoplastic • Thermoset • Rubber • Elastomers • Natural Macromolecules EMA 6165 Polymer Physics - Lecture 1

  9. Thermoplastic can be formed with heat/pressure/time recyclable crystalline or non-crystalline Thermoset can be formed with heat/pressure/time once not recyclable! Thermoplastic vs. Thermoset EMA 6165 Polymer Physics - Lecture 1

  10. Rubber butadiene, isoprene cross linked structure high strength high recovery Elastomers Thermoplastic Thermoset lightly cross linked high elongation (>400%) Rubber and Elastomers EMA 6165 Polymer Physics - Lecture 1

  11. Importance of Chemistry • Balance of Three Energies • Intermolecular • Intramolecular • Thermal (kT) • Structures • Linear • Branched EMA 6165 Polymer Physics - Lecture 1

  12. Importance of Chemistry EMA 6165 Polymer Physics - Lecture 1

  13. EMA 6165 Polymer Physics - Lecture 1

  14. Importance of Chemistry EMA 6165 Polymer Physics - Lecture 1

  15. Importance of ChemistryProtein Tertiary StructureConformational Structure EMA 6165 Polymer Physics - Lecture 1

  16. Copolymers Random Block Graft Star Ionomers Telechelic Polyelectrolytes Molar Mass Distribution Viscosity Creep Stability Processability Networks Irreversible Reversible Importance of Chemistry EMA 6165 Polymer Physics - Lecture 1

  17. Synthetic Processes • Condensation • Addition • Chain Growth • Anionic/Cationic EMA 6165 Polymer Physics - Lecture 1

  18. Condensation polymerization stepwise reaction monomer consummed early DP rises steadily long reaction time gives high molar mass monomers, dimers, trimers, etc. present reaction by products Addition polymerization chain reaction one group added per reaction DP peaks instantly long reaction time gives high conversion only polymer and monomer present no reaction by products Characteristics EMA 6165 Polymer Physics - Lecture 1

  19. Condensation PolymerizationStep Growth Process • Monomer + Monomer Dimer • Monomer + Dimer Trimer • Monomer + Trimer Tetramer • Dimer + Trimer Pentamer • n-Mer + m-Mer (n + m) Mer EMA 6165 Polymer Physics - Lecture 1

  20. Condensation Polymers • Lexan - poly(bisphenol A carbonate) • Mylar, Dacron - poly(ethylene terephthalate) • Nylons - polyamides • Kevlar, Nomex - poly(arylamide) • Kapton - (polyimide) EMA 6165 Polymer Physics - Lecture 1

  21. Addition Polymerizations • Initiation • Propagation • Termination • combination • disproportionation EMA 6165 Polymer Physics - Lecture 1

  22. Addition Polymerization 1 2 3 4 5 EMA 6165 Polymer Physics - Lecture 1

  23. Stereoisomers Isotactic Syndiotactic Atactic Geometric Head to Head Head to Tail Geometric isomers (dienes) poly(1,2- butadiene) syndio, iso, atactic poly(2,3- butadiene) cis & trans Stereochemistry - Addition Polymers EMA 6165 Polymer Physics - Lecture 1

  24. Configuration - permanent stereostructure. Rearrangement requires bond disruption. Tacticity Isotactic Syndiotactic Atactic Configurational States EMA 6165 Polymer Physics - Lecture 1

  25. Configuration - permanent stereostructure. Rearrangement requires bond disruption. Tacticity Isotactic Syndiotactic Atactic Configurational States EMA 6165 Polymer Physics - Lecture 1

  26. Configuration - permanent stereostructure. Rearrangement requires bond disruption. Tacticity Isotactic Syndiotactic Atactic Configurational States EMA 6165 Polymer Physics - Lecture 1

  27. Polymerization Processes • Solution • Bulk • Emulsion • Suspension • Interfacial • Supercritical EMA 6165 Polymer Physics - Lecture 1

  28. Summary • Thermoplastics, thermosets and elastomers • Condensation, addition, chain growth, and ionic • Condensation kinetics slow • Condensation polydispersity is high • Addition polymers exhibit stereisomerism • Composition control is critical EMA 6165 Polymer Physics - Lecture 1

  29. Agenda • Rotational States • Bond Rotational Energetics • Spatial Relationships • Characteristic Dimensions • Freely Jointed Model • Freely Rotating Model • Hindered Rotation • Random Flight Statistical Model EMA 6165 Polymer Physics - Lecture 1

  30. Chain Dimensions Definitions • Projections of vectors • Mean dimensions • Bond angles • Statistical Segments EMA 6165 Polymer Physics - Lecture 1

  31. Chain Dimensions Definitions • Projections of vectors • Mean dimensions • Bond angles • Statistical Segments EMA 6165 Polymer Physics - Lecture 1

  32. Freely Rotating Chain Model Vector Analysis EMA 6165 Polymer Physics - Lecture 1

  33. Freely Rotating Chain Model Vector Analysis (Fixed angle = 109.5°) EMA 6165 Polymer Physics - Lecture 1

  34. Freely rotating model: high temperature solvated Fixed bond angle of 109.5° expands by 2 Ignores bond rotational energy barriers (RIS) Freely Rotating ChainVector Analysis EMA 6165 Polymer Physics - Lecture 1

  35. H C C H H f f H C C H H H H C C Hindered Rotating Chain ModelIlustration of RIS Periodic fluctuations as 2p/3 EMA 6165 Polymer Physics - Lecture 1

  36. xi+1 i+2 yi f i+1 zi+1 i q xi zi i-1 yi+1 Hindered Rotating Chain ModelAssumptions • Freely rotating model: • high temperature • solvated EMA 6165 Polymer Physics - Lecture 1

  37. C C C C H H H Hindered Rotating Chain ModelIlustration of RIS H f f C C H H H H Equal probability for conformations EMA 6165 Polymer Physics - Lecture 1

  38. Hindered Rotating Chain Model EMA 6165 Polymer Physics - Lecture 1

  39. Hindered Rotating Chain Model • Hence, the Hindered Rotating Model accounts for the torsional angle potentials as well as the valence bond potentials. • For a simple polyolefin, i.e. PE, this can be readily applied to determine the effect on the mean square end to end distance. EMA 6165 Polymer Physics - Lecture 1

  40. Hindered Rotating Chain ModelPE Torsional Energy Potentials EMA 6165 Polymer Physics - Lecture 1

  41. Hindered Rotating Chain ModelPE Torsional Energy Potentials EMA 6165 Polymer Physics - Lecture 1

  42. Hindered Rotating Chain Model PETorsional Energy Potentials • Experimental value ~ (6.7+/- 0.1)nl2 • Explain discrepancies EMA 6165 Polymer Physics - Lecture 1

  43. Hindered Rotating Chain ModelPETorsional Energy Potentials EMA 6165 Polymer Physics - Lecture 1

  44. Agenda • Overview of Plastics • General Classifications • Structure/Property Relationships • Plastics Processing • Plastics Industry • Experimenting with Plastics EMA 6165 Polymer Physics - Lecture 1

  45. Polymer Structure -Property Behavior • chain thermodynamics • chain dimensions • chain environment • chain topography • mechanical behavior EMA 6165 Polymer Physics - Lecture 1

  46. Stress - Strain Response • A: Modulus-chain entanglements, bond rotation • B: Yielding-chain disentanglement, volume expansion • C: Strain Hardening- chain viscous motion, chain alignment • D: Failure-chain bond breakage, reduction in molar mass D B Stress(A.U.) A C Strain EMA 6165 Polymer Physics - Lecture 1

  47. Stress - Strain Response • A: High frequency (t << t), Low temperature (T<<Tg,Tm), high crystallinity • B: Decreasing frequency,(t ~t) (T~Tg, T<Tm) • C: Decreasing frequency (t >t), decreasing crystallinity, (T>Tg, T<Tm) • D: Low frequency (t >>t), high temperature (T>>Tg, T~Tm), low crystallinity A B Stress(A.U.) C D Strain EMA 6165 Polymer Physics - Lecture 1

  48. Chain Energy(Thermodynamics) HEAT COOL H - bonding DG = DH-TDS EMA 6165 Polymer Physics - Lecture 1

  49. Melting transition (Tm) solid to liquid first order transition modulus decreases by 2 to 3 orders of magnitude volume expansion discontinuous Glass transition (Tg) solid to liquid second order transition modulus decreases by 2 to 3 orders of magnitude elongation increases volume expansion rate increases (CTE) ~2/3 Tm Polymer Structure -Property BehaviorThermodynamics EMA 6165 Polymer Physics - Lecture 1

  50. Polymer Structure -Property BehaviorChain Dimensions • conformation • spatial arrangement • changes with rotation around bonds • configuration • bonding arrangement • changes only through bond breakage • aspect ratio (L/D) for PE (100kg/mol) • 60,000 EMA 6165 Polymer Physics - Lecture 1

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