chemeng.queensu.cacoursesCHEE490 by fjhuangjun

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									Why Study Polymer Science and Processing?
Employment Opportunities:
   135,000,000 tons of plastics alone are produced annually
   an estimated one in three research dollars in North America is
     invested in polymer science.

Scientific Interest:
    structure-property relationships of polymers and polymer
      compounds
    chemical modification of polymers for advanced applications
    polymer blending and compatiblization techniques


Engineering Design Challenges:
    life-cycle analyses
    polymer compound development
    design/optimization of polymer processing methodologies
    polymer synthesis

Introduction                  CHEE 490                             1.1
   U.S. Polymer Production (billions of pounds)
                              1993     1992                                   1993   1992
PLASTICS                                         FIBERS
Thermosetting Resins                             Cellulosics
  Phenol resins               3.08     2.92        Rayon                      0.28   0.28
  Urea resins                 1.74     1.55        Acetate                    0.23   0.22
  Polyesters (unsaturated)    1.26     1.18
  Epoxies                     0.51     0.46      Noncellulosics
  Melamine resins             0.27     0.23        Polyester                  3.56   3.58
                                                   Nylon                      2.66   2.56
Thermoplastic Resins                               Olefin                     2.14   2.00
  Low-density polyethylene    12.04    11.92       Acrylic                    0.43   0.44
  PVC and copolymers          10.26     9.99     Total                        9.30   9.07
  High-density polyethylene   9.91      9.81
  Polystyrene                 5.37      5.10     SYNTHETIC RUBBER
  Polypropylene               8.61      8.42     Styrene-butadiene rubber     1.89   1.92
                                                 Polybutadiene                1.03   1.02
Total                         53.06    51.57     Ethylene-propylene rubber    0.58   0.58
                                                 Nitrile rubber (NBR)         0.14   0.13
                                                 Other                        1.37   1.42
                                                 Total                        5.00   5.07
Chemical and Engineering News, April 11, 1994.
                                                 TOTAL PRODUCTION            67.35   65.71
   Introduction                            CHEE 490                                  1.2
Polymer Science and Processing Technology
 Successful product design requires a knowledge of:
     the requirements of the final product
     the behaviour of polymeric materials
     commercial polymer processing technology
     relevant cost and market factors.




 At the heart of polymer science and
 technology is molecular structure. It
 dictates not only final product properties,
 but polymer synthesis and processing
 methods.

Introduction                     CHEE 490             1.3
Classification of Polymer Applications
1. Elastomers
     static uses: gaskets, hoses
     dynamic uses: tires, sports equipment

2. Adhesives
     structural: epoxy resins
     non-structural: pressure-sensitive tapes, hot-melt adhesives

3. Coatings
     lacquers, paints

4. Plastics
     semi-crystalline: automobile exterior
     amorphous: packaging films, plexi-glass

5. Fibres
     natural/modified: cotton, rayon
     synthetic: carpeting, apparel
Introduction                   CHEE 490                              1.4
Emphasis of Course Material (Weeks 1-6)
Each of the five applications will be examined from the following
perspectives:
    Industrial requirements for end-use and processing

       Basic testing methods

       Polymer compound formulations
         » essential polymer properties
         » compound additives

       Relevant engineering science
         » Elastomers: origin of elasticity, crosslinking, reinforcement
         » Adhesives: surface energy
         » Coatings: viscosity
         » Plastics: mechanical properties, polymer composites
         » Fibres: crystallization


Introduction                      CHEE 490                            1.5
Emphasis of Course Material (Weeks 7-12)
Each of the five applications will be examined from the following
perspectives:
    Industrial polymer processing techniques
        » extrusion
        » injection molding
        » fibre spinning
        » compression molding
        » polymer/additive blending

       Key processing variables
         » polymer compound rheology
         » fluid mechanics

       Assessment of processing variables




Introduction                    CHEE 490                            1.6
Design Project
Develop a polymer compound and processing method for a
component of your choice.

1. Define engineering and aesthetic qualities.

2. Propose a compounding recipe that will satisfy these
   requirements.

3. Recommend appropriate processing techniques for
   manufacturing the product.

Examples?
  Contact lens, medical catheter, biodegradable packaging,
  artificial joint, high-performance tire tread...




Introduction                    CHEE 490                     1.7
Basics of Polymer Structure
What distinguishes polymers from other organic compounds is
molecular weight and dimension.




Differences in composition, architecture and molecular weight
give rise to differences in mechanical properties (strength, elasticity,
toughness) and chemical properties (solubility, aging).

Introduction                     CHEE 490                             1.8
  Polymer Classification: Terminology

While we have chosen
an applications
perspective on polymer
classification, many
alternate schemes are
widely used.

These are usually
composition/property
specific, as opposed to
applications oriented.




  Introduction            CHEE 490      1.9
Polymer Classification: Thermoplastic/Thermoset
One of the most practical and useful classification of polymer
compounds is based on their ability to be refabricated.

Thermoplastic: polymers that can be heat-softened in order to
               process into a desired form.
    Polystyrene, polyethylene
    recyclable food containers


Thermoset: polymers whose individual chains have been
          chemically crosslinked by covalent bonds and therefore
          resist heat softening, creep and solvent attack.
    Phenol-formaldehyde resins, melamine paints
    permanent adhesives, coatings




Introduction                    CHEE 490                         1.10
Polymer Classification: Chain Architecture
Linear: A linear polymer chain is one without branches. Its actual
conformation may not be “line-like”, but varies with chain stiffness,
crystallinity and applied stresses.

Branched: Chains with an appreciable number of side-chains are
classified as branched. These side chains may differ in composition
from the polymer backbone.

Crosslinked: A continuous
network of polymer chains is
a crosslinked condition. In effect,
there is just one polymer chain
of infinite molecular weight.

Chain architecture has a dramatic
effect on properties such as
viscosity, elasticity and temperature
stability.
Introduction                     CHEE 490                           1.11
Polymer Classification: Chemical Microstructure
Homopolymers: polymers derived from a single monomer (can be
               linear, branched or crosslinked).
   poly(ethylene), poly(butadiene).
Random copolymers: two monomers randomly distributed in chain.
    AABAAABBABAABBA
    poly(acrylonitrile-ran-butadiene)
Alternating copolymers: two monomers incorporated sequentially
     ABABABABABABABAB
     poly(styrene-alt-maleic anhydride)
Block copolymers: linear arrangement of blocks of high mol weight
    AAAAAAAAAAABBBBBBBBBBBBBBBAAAAAAAA
    polystyrene-block-polybutadiene-block-polystyrene or
      poly(styrene-b-butadiene-b-styrene)

Graft copolymers: differing backbone and side-chain monomers
    poly(isobutylene-graft-butadiene)

Introduction                  CHEE 490                           1.12
Polymer Classification: Chemical Class
A popular classification scheme amongst chemists is based on
polymer functionality.
Polyesters:                                       O
    poly(ethylene terephthalate) - Dacron        C O

Polyamides:                                       H O
    poly(caprolactam) - nylon 6                  N C
Urethanes:
    carbamate linkages through reaction          H O
     of diisocyanates and diols.                  N C O

Another (!) classification scheme, again favoured by chemists is
based on differences between the polymer and constituent
monomer(s).
    Condensation polymers: synthesis involves elimination of
     some small molecule (H2O in the preparation of nylon)
    Addition polymer: formed without loss of a small molecule
     i.e. ethylene polymerization to generate poly(ethylene)
Introduction                   CHEE 490                            1.13
Additive Classification: Terminology
It is relatively rare for an article to be made from polymer alone.
Most are polymer compounds, consisting of a mixture of polymer
and various additives. These include:
Fillers: solid additives used to modify physical properties.
      Dilution - talc
      Reinforcing - carbon black in tires
      Toughening - rubber in ABS plastic

Plasticizers: non-volatile solvents added to improve flexibility
    Dialkyl phthalates in poly(vinylchloride)

Colourants: additives used to change product aesthetics
    Pigments - soluble colourants
    Dyestuffs - insoluble additives

Antioxidants: compounds that reduce polymer degradation through
              intervention in free radical reactions
Introduction                     CHEE 490                             1.14
Chain-A linear polymer formed by covalent linking of monomeric units.
Backbone-Used in graft copolymer nomenclature to describe the chain onto which the graft is formed.
Side chain-The grafted chain in a graft copolymer.
Cross-link-A structure bonding two or more chains together.
Network-A three-dimensional polymer structure, where (ideally) all of the chains are connected through
cross-links.
Multicomponent polymer, multipolymer, and multicomponent molecule-General terms describing intimate
solutions, blends, or bonded combinations of two or more polymers.
Copolymer-Polymers that are derived from more than one species of monomer.
Block-A portion of a polymer molecule in which the monomeric units have at least one constitutional or
configurational feature absent from the adjacent portions.
Block copolymer-A combination of two or more chains of constitutionally or configurationally different
features linked in a linear fashion.
Graft copolymer-A combination of two or more chains of constitutionally or configurationally different
features, one of which serves as a backbone main chain, and at least one of which is bonded at some
point(s) along the backbone and constitutes a side chain.
Polymer blend-An intimate combination of two or more polymer chains of constitutionally or
configurationally different features which are not bonded to each other.
Interpenetrating polymer network-An intimate combination of two polymers both in network form, at least
one of which is synthesized and/or cross-linked in the immediate presence of the other.
Semi-interpenetrating polymer network -A combination of two polymers, one crosslinked and one linear,
at least one of which was synthesized and/or cross-linked in the immediate presence of the other.
Star polymer-Three or more chains linked at one end through a central moiety.
Star block copolymer-Three or more chains of different constitutional or configurational features linked at
one end through a central moiety.

								
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