Polymer Chemistry

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????? Polymer Chemistry

• ? ? ?
• Jihperng (Jim) Leu
• Fall Semester, 2004

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Grading

• 35 Report
• 15 Presentation / Attendance
• 25 Mid-term Exam
• 25 Final Exam
• 5-point bonus point if you provide me
  feedback/suggestion during this semester
• (Final grade will be normalized based on 100
  points)
• Class policy
• NCTU Honor Code
• Medical record is required for missing exams
• Dozing.. is wasting your time in this class!
  STAND UP and stretch in the back of the
  classroom

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Top 10 List Polymer products change our life
significantly

• Ties (Synthetic rubber)
• Non-sticky pan (Teflon)
• Polyethylene
• Stocking (Nylon)
• Polystyrene
• PVF
• PMMA
• Silicone
• Rayon
• Piping (PVC)
• We will review this list in the end of this course

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Show and Tell

• Compact Disk
• Zipper bag
• PVC tubing
• Soda bottle
• Jacket for ski
• Rayon
• Rubber

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Introduction
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History of Polymers
1927 PVC 1934 PE ICI 1934 Nylon Du
Pont Nobel Prize winners 1953 Herman
Staudinger 1974 Paul Flory
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Top 2 High-volume Polymers

• Polyethylene
• 50M tons/yr (2003)
• packaging, consumer goods, pipe, durable
  equipment and industrial machinery
• PVC
• 27M tons/yr (2002)
• Building 56 Packaging 15 Consumer goods 10
  Electronics industries 9 Agriculture 5 Others
  5.

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History of Polyethylene

• Polyethylene, was discovered largely by accident
  in 1933 by scientists working for ICI. From
  1937 pilot plant work proceeded but only a small
  amount of polymer was produced. The first plant
  came into operation in September 1939 and the
  resultant product, named "Polythene" by ICI, was
  to have a major impact on the war effort. It was
  found that the long chain, low density white
  polymer could be extruded as film and coated
  around wires and cables to give greatly enhanced
  performance. Polythene was a superb insulator
  with high dielectric and low loss factor and was
  thus in great demand for submarine cables, radar
  applications, etc.Major production continued
  from 1942 and ICI licensed other companies
  thereafter in the production of high pressure
  polyethylene which produced the low density
  product - LDPE. However, the extreme conditions
  and costs for production coupled with low
  temperature softening, creep and stress cracking
  of LDPE limited the full potential of the
  polyethylene family of polymers in film blowing
  and injection moulding volume applications.The
  development of new improved conditions for
  manufacture and control of molecular structures
  was to create accelerating and dramatic changes
  in the growth of polyethylene and other
  polyolefin polymers. (See Karl Ziegler and Giulio
  Natta) The subsequent huge range of products,
  especially in packaging films and containers
  coupled with great design and production
  flexibility through controlled material
  properties, has affected almost every aspect of
  modern life
• Source http//www.plastiquarian.com/polyethy.htm

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Applications of some polymers

• HDPE ??? gt
• LDPE ??? ??? ??
• ????(PS) ???? ?????
• ????(PVC) bottles, window frames, pipes,
  flooring, wallpaper, toys, car seats, guttering,
  cable insulation, credit cards, and medical
  products such as blood bags, IV tubing and much
  more. ?? ??? ?? gt
• ???(PU) ???????? ?????????
• ??66 ????? ?? ????
• PET ???
• ???? (PC) ???????????????????????????????????????
  ???????

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Basic Definition and Nomenclatures

• Definition
• Polymer A substance composed of molecules with
  many repeating units (gt 10,000)
• (segments, monomers, repeating units,
  sub-units)
• Monomer Staring material from which polymer is
  formed
• Dimer, trimer, oligomer
• Monomer vs polymer (one-unit vs many units)
• Macromolecules large molecules (such as
  proteins, synthetic polymers, etc)

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Natural Polymers

• Proteins
• enzymes, muscles, tissue, hair, wool, silk
• Carbohydrates
• polysaccharides, starch, cellulose, rayon
  (reconstituted cellulose)
• Nucleic Acids - DNA, RNA

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Classification by Use

• Plastics ??
• HDPE, LDPE, Lexan, plexiglass, teflon,
  polystyrene
• Fibers ??
• Nylon, orlon, kevlar, rayon
• Elastomers ??
• rubber, spandex, poly(urethane) foam
• Coatings ??
• paints, varnishes, enamels, formica,
  Poly(urethane)
• Adhesives ???
• glues, cement, "scotch tape", epoxy, Hair spray

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Adhesives

• Adhesives are polymer-based formulations used to
  bond two surfaces together. Adhesives can be
  either reactive (form chemical bonds) or adhere
  by physical (van der Waals, ionic, etc) bonds.
• Modern adhesives are classified either by the way
  that they are used or by their chemical
  constituents.
• Anaerobics - used to bond metal surfaces together
  when air is excluded. They are generally based on
  acrylic resins.
• Cyanoacrylates - reactive cyanoacrylic adhesives
  that cure in the presence of moisture. They
  solidify in seconds.
• Toughened Acrylics - general use, strong
  acrylic-based adhesive. It's applied as a
  two-part, resin/catalyst system.
• Epoxies - adhesives consisting of epoxy resin and
  hardener. These one-part, or two-part adhesives
  are extremely strong and versatile.
• Polyurethanes - fast-cure, two-part adhesives
  used for bonding glass-reinforced plastics.
• Modified Phenolics - phenolic resins for bonding
  metal to metal, or metal to wood. They require
  pressure and heat to cure.
• Hot Melts - semi-crystalline polymers that bond
  physically. Joints form quickly, but are not very
  strong.
• Plastisols - poly(vinyl chloride) based
  dispersions that require heat to harden. Once
  set, the joint is tough and resilient.
• Rubber Adhesives - solutions or latexes of rubber
  that solidify by loss of solvent. Do not give
  load-bearing joints.
• Poly(vinyl acetates) - PVA emulsions for use in
  bonding porous surfaces. Used in the packaging
  industry.
• Pressure Sensitive Adhesives - used for labels
  and tapes. They don't solidify, rather stay in
  the rubbery flow regime.

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Polymer Nomenclature
In most cases poly monomer name Trade names
Acronyms Examples PMMA and Nylon PMMA
Poly(methyl methacrylate) PLEXIGLASSTM
NylonTM (Du Pont)
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Homopolymers
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Examples - Homopolymers

• Polyethylene
• Polypropylene
• Polytetrafluoroethlyene
• Polystyrene
• PMMA
• PVC
• PVA
• PEG
• PET
• Nylon
• Assignment Chemical structure, Tg, modulus,
  applications
• Due next Monday

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Copolymers from different monomers
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Skeletal structure
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Classification of Polymers

• Thermoplastics (heat/pressure deformable)
• Deformable, processible as viscous melt
• Hard at its use temperature
• Liner chain structures
• 2 kinds
• Crystalline/sem-crystalline polymers (Tm)
• Amorphous polymer (Tg) PS, PC, PMMA
• Thermosetting (Heat cross-linked)
• Sets cross-linked cured
• Network or cross-linked architechure
• Degrade rather than melt upon heating
• Ealstomers crosslinked rubbery polymers
• Stretchable, recoverable
• Low cross-link density

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Modulus vs Tg for thermoplastic polymers
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Crystalline vs Amorphous
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Molecular Weight Distribution
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Review Next Week

• Table 1.1 and key properties
• Polymer classification
• Finalize top-10 list
• Thermosetting vs thermoplastic polymers
• 10/22 Wednesday RM210 Seminar
• Stan Yang, Introduction of polymers for
  biomedical applications