1. Thermoplastic polymers processed by a heat-form-cool cycle
John Summerscales

2. Summary of lecture basic chemical names addition polymers
configuration/conformation
stereoregularity/tacticity
crystalline or amorphous
transition temperatures
condensation polymers
ring-opening polymers

3. Naming basic chemicals
Number
C atoms
Prefix
single bond
double bond
triple bond 1
Meth-
-ane 2
Eth-
-ene
-yne 3
Prop- 4
But- 5
Pent- 6
Hex- 7
Hept- 8
Oct- 9
Non- 10
Dec-

4. Basic chemicals C atoms Name Formula CnH2n+2 Boiling point 1 Methane
-164°C (gas) 2
Ethane
C2H6
-89°C (gas) 3
Propane
C3H8
-42°C (gas) 4
Butane
C4H10
-0.5°C (gas) 5
Pentane
C5H12
36°C (liquid) 6
Hexane
C6H14
69°C (liquid) 7
Heptane
C7H16
98°C (liquid) 8
Octane
C8H18
125°C (liquid) 9
Nonane
C9H20
151°C (liquid) 10
Decane
C10H22
174°C (liquid)
Paraffins/waxes
C20H42 melts at 37 °C
quasi-solid
1000+
Polyethylene
H[CH2]nH
solid
Transition temperature data from

5. Bond rotation Movie of rotation about a single bond
file taken from
Movie of rotation with different side groups
file taken from

6. Geometric isomers
cis:
trans:

7. Chemical Groups (reactants)
Acid
Alcohol
Amine
NB: nitrogen in amine has a free p-orbital which can become part of a π-bond C O H HO H N

8. Chemical Groups (products)
Ester
Amide
Ether C O C O N H O

9. Polymers
Polymers are class of materials where many small molecules (monomers) are linked together by covalent bonds to form long chains or networks
an alternative name for polymers is macromolecules
a homopolymer has only 1 repeating unit
a copolymer has 2 different repeating units
a terpolymer has 3 different repeating units.

10. Polymers
Thermoplastic - usually long straight chains sometimes with short branches
copolymers AB (and terpolymers ABC) can be
alternating ---ABABABABAB---
block ---AAABBAAABB---
graft (type B branches on type A backbone)
random ---AABABBBAAB---
Thermoset - usually 3-dimensional networks
Elastomers - 3-D networks with sparse interlinks between chains (e.g. rubber)

11. Addition polymers reaction by opening double bonds
all atoms from reactants end up in the product
n CH2=CHX reacts to become [- CH2-CHX-]n
if X = H, the polymer is polyethylene
if X = CH3, the polymer is polypropylene
if X = Cl, the polymer is polyvinylchloride
if X = C6H5, the polymer is polystyrene
... this list is not exhaustive
if monomer is CF2=CF2, the polymer is polytetrafluoroethylene

12. Configuration/Conformation
the arrangements of atoms on the polymer chain
fixed relative positions of atoms
Conformation
the arrangement of the atoms in space
regular linear chains can crystallise
branched/bulky side-groups or irregular copolymers have longer repeat units and are thus less likely to crystallise but more likely to be amorphous

13. Stereoregularity -> tacticity
Isotactic
characteristic groups all on the same side of the polymer chain
Syndiotactic
characteristic groups on alternate sides along polymer chain
Atactic - characteristic groups located at random along the polymer chain
images from

14. Crystalline vs amorphous
Crystalline polymers
molecules pack more closely leading to:
higher density
better mechanical properties (more bonds/m3)
better resistance to environmental degradation
NB: common polymers are partially crystalline
crystallites distributed in an amorphous matrix
Amorphous polymers
random configuration
reduced properties re. crystalline materials
transparent to white light (e.g. PS, PC, PMMA)

15. Crystallinity Two model structures have been proposed
Images from respectively
Fringed micelle Folded lamella

16. Transition temperatures
Tg = Glass transition temperature
segmental motion is frozen out
brittle elastic below Tg
tough/viscoelastic above Tg
Tm = Crystalline melting point
only occurs in crystallites
both temperatures may be a range rather than a specific temperature

17. Transition temperatures
Specific volume
Liquid
Rubbery
Amorphous/ glassy
Crystalline solid
Temperature
Tg Tm

18. Condensation polymers
XOH + HY  XY + H2O
HOXOH + HYH  HOXYH + H2O
further reactions with HOXOH and HYH will produce a linear molecule

19. Condensation polymers
Acid + base  salt + water
HCl + NaOH  NaCl + H2O
Acid + alcohol  ester + water
R.C=O.OH + HO.R’  R.C=O.O.R’ + H2O
Acid + amine  amide + water
R.C=O.OH + H2N.R’  R.C=O.HN.R’ + H2O
If two reactive sites on each molecule, then a polymer chain will result

20. Ring-opening polymers
HOXOH + HYH  HOXYH +H2O
further reactions with HOXOH and HYH will produce a linear molecule
HOXH + HOXH  HOXXH +H2O
i.e. both reactants might be on one molecule
but such a system could react with itself to form a cyclic molecule if X > 4C atoms
such a cyclic molecule can polymerise without loss of water (H2O already removed in cyclisation reaction)

21. Ring-opening polymers
Ring-opening polymerisation during composite manufacture has potential to produce thermoplastic matrix composites from RTM/RIFT
caprolactam to produce polyamide 6 (e.g. DSM Fiber Intermediates APA-6),
laurolactam to produce polyamide 12 (e.g. EMS-Grivory APLC12), and
cyclic butylene terephthalate oligomers to produce PBT polyester (e.g. Cyclics Corporation).

22. Voluntary Plastic Container Coding System
abc
Voluntary Plastic Container Coding System
proposed by Society for the Plastics Industry (SPI) in the United States of America
remember Tm = Tg + 200°C (±~50°C) so some common thermoplastics are.....

23. LDPE 4 -130 +105 HDPE 2 -125 +135 PP 5 PA6,6 7 +55 +255 PVC (V) 3 --
Polymer
Acronym
Coding
Tg (ºC)
Tm (ºC)
Morphlgy
Low-density polyethylene
LDPE 4
-130
+105
crystalline
High-density polyethylene
HDPE 2
-125
+135
Polypropylene PP 5
Polyamide (nylon) 6,6
PA6,6 7
+55
+255
Poly vinylchloride
PVC (V) 3 --
amorphous
Polystyrene PS 6
Polyethylene terephthalate
PET (PETE) 1
265
Polycarbonate PC
Polyoxymethylene (acetal)
POM
< -150
+180
Polyurethane PU
+140
Poly ether ether ketone
PEEK
+144
367

24. Periodic Table of Thermoplastics (Tangram Technology) http://polymer

25. Summary of thermoplastics lecture
basic chemical names
addition polymers
configuration/conformation
stereoregularity/tacticity
crystalline or amorphous
transition temperatures
condensation polymers
ring-opening polymers

26. MATS117 continues with thermosetting polymers….

27. Thermosets generally supplied as a liquid
cross-linked (cured) by chemicals (and heat)
heat increases the rate of cure
heat reduces the instantaneous viscosity
cure decreases the viscosity over time
product is a 3D molecular network
whereas a thermoplastic is usually a 2D chain

28. Summary (key polymers)
Polymern
Curing
Properties
Ph-F
Condensation
Low-cost, brittle, FST
Epoxy
Ring-opening
High-cost,
High-performance
UPE
Addition
Intermediate cost
Balanced performance