Polyamides (Amino acid)
Different end groups
Same end groups
Nylon - 66
Growth in addition and condensation polymerization
37. The Crystalline Melting
Melting is essentially the reverse of crystallization. Several
characteristics of the melting behaviour of polymers distinguish
them from other materials such as;
There is not a single melting temperatur
Lec25 (Cl 27)
NMR for Sequence Isomerism
NMR can also provide clear evidence of sequence isomerism in
polymers. For example, poly(vinylidene fluoride), or PVDF
polymer which contains H-H and T-T sequences.
Because the 19F nucleus has a spin num
Thermal Transitions in Polymers
Crystallization and Melting
What happens to a polymer when its
cooled slowly from the melting
If the chain structure is regular, it will
36. Mechanism of Crystallization:
Critical Nucleus Size (CTS)
The critical nucleus size is given by the values of I and x that
By solving the two simultaneous equations, the thickness of
critical nucleus can be determi
Crystal Structure and Morphology
A distribution of conformations may be found in the polymer
melt. Upon cooling, or precipitation from dilute solutions,
ordered structures may be formed as a result crystallization.
Crystal structures are determ
CH8: Structure and Morphology
Three important phenomena of polymeric
materials are crystallization, melting, and
the glass transition.
The glass-transition phenomenon occurs
with amorphous or noncrystallizable
polymers that, when co
19. Spectroscopy & Characterization
How do you know if a vinyl polymer is isotactic, atactic etc.?
Sequence distribution, MW distribution in copolymer
Lec11: Polymerization Processes
Need to consider
Viscosity of the bulk polymers may become a challenge
Exothermic heat evolved and its proper dissipation is necessary
Larger/industrial scale polymerisation use batch or continuous process.
Nework Formation Mechanism
Bifunctional molecules make dimers and trifunctional (f>2) or multifunctional
monomers can actually give you network or interconnected polymers.
If more than two hydroxyl groups are present on one of the monome
Lec 10: Carbanion, Carbcation and
Ionic Addition Polymerisation
Many ionic polymerisation proceed at much higher rates than free-radical
polymerisation, because the concentration of actively propagating chains is
very much higher.
In a syndiotactic configuration, the R
groups alternate sides of the chain while
for random positioning, the term atactic
configuration is used.
2. Stereo Isomerism
Home work Problems
The number-average molecular weight of a polypropylene is 1,000,000
g/mol. Compute the degree of polymerization.
Home work Problems
Also, what will be the PDI?
Kinetics of Condensation
Generally, the reactions are reversible, thus the eliminated water must be
removed if a high molecular weight polymer is to be formed
Monomer + Monomer
Monomer + Dimer
Monomer + Trimer
Dimer + Dimer
Dimer + Trim