化学工学424

Home > Preview

The flashcards below were created by user TJB on FreezingBlue Flashcards.


  1. Polymer
    Macromolecule generated through sequential reaction of elementary units
  2. Monomer
    Molecule with minimum functionality of 2 that reacts to form the structural units of a polymer
  3. Oligomer
    Short chains synthesized from reaction of several monomers
  4. Repeat Units
    Structure of minimal size to generate polymer
  5. Degree of Polymerization (DP)
    • Number of repeat units
    • DPn=Xn=Mn/Mo

    • Mn=number average MW
    • Mo=MW of repeat Unit
  6. Natural Polymers
    • Of biological origin
    • (Proteins, polysaccharides, etc.)
  7. Polysaccharides
    Very limited processability, as melting temperature and poor solubility
  8. Linear Polymer
    • HDPE
    • PVC
    • Polyester
  9. Branched Polymer
    • LDPE
    • LLDPE
  10. Homopolymer
    • Polymer with 1 repeat unit
    • AAAAAAAA
  11. Copolymer
    Polymer with more than 1 repeat unit
  12. Random Copolymer
    • AAABABAAABBBBAA...
    • poly(A-ran-B)
  13. Alternating Copolymer
    • ABABABABAB
    • poly(A-alt-B)
  14. Block Copolymers
    • AAAABBBB
    • AB blockcopolymer
  15. Thermoset
    Initial mixture of reactive low molecular mass compounds react upon heating mold to from insoluble network
  16. Thermoplastic
    Becomes fluid upon heating
  17. Isotactic
    All chiral centers are the same
  18. Syndiotactic
    Chiral centers alternate
  19. Atactic
    Chiral centers are random
  20. Chain Entanglement
    Allows long chains to act as they were longer. Causes multiple chains to act together
  21. Glass Transition Temperature (Tg)
    Flexibility of amorphous polymers is reduced when they are cooled below a temperature
  22. Melting Temperature (Tg)
    Temperature range where total or whole polymer chain mobility occurs
  23. Polydispersity Index (PDI)
    • PDI=Mw/Mn
    • Mw≥Mn
    • Measures the distribution on molecular mass in a sample closer to 1, more uniform the polymers
  24. Step-Growth Polymerization
    Many monomers react at once
  25. Chain-Growth
    Growth occurs one unit at a time
  26. Trommsdorff Effect
    Viscosity of the solution increases the rate of termination decreases, large rate of polymerization leads to an explosion
  27. Ideal Copolymerization Rates
    r1=r2=1
  28. Alternating Copolymerization Rates
    r1•r2=0
  29. Block Copolymerization Rates
    r1>1, r2>1
  30. Can you melt a thermoplastic?
    No
  31. Does every polymer have a Tg?
    Yes
  32. A soft polymer has a ____ Tg
    Low
  33. If you increase the number of small chains in your polymer sample, Mn will:
    Decrease
  34. What is cotton composed of?
    Cellulose
  35. Which polymerization technique is the fastest to provide high MW polymers?
    Chain Growth
  36. Unreacted Monomers are an issue for which polymerization method?
    Chain Growth
  37. For chain growth polymerization: higher temperature leads to ____ DPn
    Lower
  38. The molecular weight of the polymer produced is too high so what can you change?
    • Increase initiator
    • Increase Temperature
    • Increase the chain transfer agent concentration
  39. What is the ceiling temperature (Tc)?
    It is the temperature when the rate of polymerization equals the rate of depolymerization
  40. Rank the Tg, Tm and Tc
    Tg<Tm<Tc
  41. Give the name of one technique to measure the MW distribution of a polymer?
    • MALDI
    • Mass Spec
  42. Which technique gives the larger number end-group analysis or viscosity?
    Viscosity (Mv)
  43. Why is the Trommsdorff effect is only problematic once the monomer conversion is high?
    At high conversion the solution becomes viscous where the reaction releases more heat and causes autoacceleration
  44. What can you do in a batch process to ensure that you reach 100% conversion?
    Increase concentration of initiator
  45. What process change would you do to reach 100% conversion at a lower cost for a batch reactor?
    Feed initiator continuously
  46. What are the parameters used to slow down the rate of polymerization?
    • Decrease Temperature
    • Decrease Initiator
    • Decrease Monomer
  47. Why is losing the temperature control of a radical polymerization be bad?
    The reaction is exothermic so losing control of the temperature can increase the reaction and lead to a runaway reaction and the Trommsdorff effect
  48. Why aren't polymers produced with the highest MW possible?
    The longer the polymer the more viscous it is making it difficult to process
  49. What is the difference between suspension polymerization and emulsion polymerization?
    • Suspension: Mechanical mixing required
    • Emulsion: Chemically stabilized particle
  50. In copolymerization studies, the monomer reactivity ratio provides information on?
    The instantaneous composition of the copolymer knowing the monomer composition
  51. When the degree of crosslinking goes up the MW of the polymer
    Increases
  52. The crosslinking density of an elastomer is ____ than the one of a thermoset
    Lower
  53. A 10w% solution of polystyrene in toluene is ___ viscous than a 30% polylstyrene
    More
  54. Which one of these PP is industrially relevant?
    Attactic
    Isotactic
    Syndiotactic
    Isotactic
  55. Rank the polydispersities of the following polymers. (Polyethylene, Nylon 6,6, Polybutadiene)
    • Largest: Polyethylene
    • Middle: Nylon 6,6
    • Smallest: Polybutadiene
  56. What does the polymer ABS stand for?
    • A: Acrylonitrile (CH2CHCN)
    • B: Butadiene
    • S: Styrene
  57. Emulsion Polymerization Phase I (Micelles, Monomer droplets, Particle number, Particle Size)
    • Micelles: Present
    • Monomer Droplets: Present
    • Particle Number: Increase
    • Particle Size: Increase
  58. Emulsion Polymerization Phase II (Micelles, Monomer droplets, Particle number, Particle Size)
    • Micelles: Absent
    • Monomer Droplets: Present
    • Particle Number: Constant
    • Particle Size: Increase
  59. Emulsion Polymerization Phase III (Micelles, Monomer droplets, Particle number, Particle Size)
    • Micelles: Absent
    • Monomer Droplets: Absent
    • Particle Number: Constant
    • Particle Size: Constant
  60. What does HDPE, UHMWPE and LLDPE stand for?
    • HDPE: High density polyethylene
    • UHMWPE: Ultra high molecular weight polyethylene
    • LLDPE Linear Low density polyethylene
  61. Which one has the lowest crystallinity? (HDPE, UHMWPE, LLDPE)
    LLDPE
  62. How is the degree crystallinity of LLDPE controlled?
    Control the amount of olefins and the lengths of them
  63. Why is it impossible to make copolymer of propylene and acrylic acid via insertion polymerization?
    Acrylic acid has oxygen which kills the propylene catalyst
  64. Why is preparing high molecular weight polymers difficult with cationic polymerization?
    They are unstable and terminates easily
  65. How can you synthesize a polymer with amine groups at both ends of the chain?
    Use an excess of diamines
  66. Carother could not prepare high molecular polyester because he couldn't control the stoich between the monomers. What solution did he find?
    He precipitated the monomers as a salt  with a 1:1 stoic ratio
  67. Polymer: LLDPE
    Initiator:
    Reaction Type:
    • Initiator: Z-N
    • Reaction Type: Insertion
  68. Polymer: LDPE
    Initiator:
    Reaction Type:
    • Initiator: ROOR
    • Reaction Type: Radical
  69. Polymer: 1,2 Polybutadiene
    Initiator:
    Reaction Type:
    • Initiator: nBuLi anionic
    • Reaction Type: Anionic
  70. Polymer: PS
    Initiator:
    Reaction Type:
    • Initiator: ROOR
    • Reaction Type: Radical
  71. Polymer: PEG 4000
    Initiator:
    Reaction Type:
    • Initiator: NaOH
    • Reaction Type: Anionic
  72. Polymer: PVC
    Initiator:
    Reaction Type:
    • Initiator: ROOR
    • Reaction Type: Radical
  73. Polymer: HDPE
    Initiator:
    Reaction Type:
    • Initiator: Z-N
    • Reaction Type: Insertion
  74. Polymer: Syndiotactic PP
    Initiator:
    Reaction Type:
    • Initiator: Z-N
    • Reaction Type: Insertion
  75. Polymer: 1,4 cis butadiene
    Initiator:
    Reaction Type:
    • Initiator: nBu-Li
    • Reaction Type: Anionic
  76. If AB type Xn=
    DP
  77. If AA BB type Xn=
    2DP
  78. Average degree of polymerization equation (non stoichiometric)
    • Xn=(1+r)/(1+r-2rp)
    • [Ao]/[Bo]=r
    • A<B
  79. Average degree of polymerization (Stoichiometric)
    • Xn=1/(1-p)
    • r=1
  80. Extent of Reaction equation (p)
    (No-N)/No
  81. DP vs. Temp for step growth
    • Higher Temp, Higher DP
    • Linear Lines
  82. DP vs. Temp for Chain growth
    • Higher Temp, Lower DP
    • Straight Lines

Card Set Information

Author:
TJB
ID:
326705
Filename:
化学工学424
Updated:
2016-12-12 06:57:00
Tags:
化学工学424
Folders:

Description:
Final
Show Answers:

Home > Flashcards > Print Preview