POLYMER SCIENCE AND TECHNOLOGY
(CHEN 507)
PRESENTATION
ON
EFFECT OF INTERMOLECULAR BONDING ON Tm
AND
EFFECT OF STRUCTURE ON Tm
BY
GROUP F
PRESENTED AT
DEPARTMENT OF CHEMICAL ENGINEERING,
AHMADU BELLO UNIVERSITY, ZARIA
FEBRUARY, 2024.
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OUTLINE
INTRODUCTION
POLYMERS
EFFECT OF INTERMOLECULAR BONDING IN POLYMERS
EFFECT OF STRUCTURE ON TM IN POLYMER MATERIALS
CONCLUSION
REFERENCE
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INTRODUCTION
Tm polymer is the temperature at which a solid plastic material
changes into a softer, flexible form or a solid amorphous form. The
conversion occurs because the bond holding the plastic due to
intermolecular force becomes loose or breaks down.
Molecular structure in polymer materials refers to the arrangement
of monomer units within polymer chains and the spatial organization
of polymer chains in the solid state.
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POLYMERS
 Polymers is larger molecule (macromolecule) built up by the repetition of small chemical units
 Monomer is defined as any molecule that can be converted by combining with other molecules
of the same or different type.
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REACTION OF MONOMERS
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TYPES OF INTERMOLECULAR BONDING IN POLYMERS
PRIMARY BONDS
A. IONIC
B. COVALENT
C. METALLIC
SECONDARY BONDS
A. DIPOLE
B. HYDROGEN
C. INDUCTION
D. VAN DER WAALS
(DISPERSION)
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COUN’T
VAN DER WAALS FORCES: These forces
arise from temporary fluctuations in
electron density along polymer chains and
between adjacent chains. They include
dispersion forces and dipole-dipole
interactions.
HYDROGEN BONDING: Some polymers,
such as polyamides (nylons) and polyesters,
contain functional groups capable of
forming hydrogen bonds. These bonds
enhance intermolecular interactions and
may increase Tm.
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INFLUENCE ON TM
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COUN’T
The polymer melting point Tm is increased if the
double bonds, aromatic groups, bulky or large side
groups are present in the polymer chain because they
restrict the flexibility of the chain. The branching of
chains causes the reduction of melting point, as
defects are produced because of the branching.
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C0UN’T
The strength and type of intermolecular bonding in polymers
significantly impact their Tm.
Polymers with strong intermolecular bonds, such as hydrogen bonds
in nylon, generally have higher Tm values because more energy is
required to overcome these bonds and transition from the solid to
the liquid state.
Polymers with weaker intermolecular forces, such as low-density
polyethylene (LDPE), have lower Tm values because the
intermolecular bonds are easier to break.
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COUN’T
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FACTORS AFFECTING THE CRYSTALLINE MELTING POINT,
TM
Intermolecular Bonding
The decrease in the cohesive energy density associated with the decrease in the density of sites of or intermolecular
bonding(increase space btw polar group) leads to a reduction in the melting points.
Effect of Structure
A high structural regularity that permits close packing of the chains couple with the initial chain flexibility leads
to an unexpectedly high Tm
Chain Flexibility
Polymers with rigid chains would be expected to have higher Tm than those with flexible molecules.
Copolymerization
The effect of copolymerization on Tm depends on the degree of compatibility of the comonomer.
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CONCLUSION
Both intermolecular bonding and molecular structure
significantly impact the Tm of polymer materials
Stronger intermolecular bonds, such as hydrogen bonding,
lead to higher Tm values
Structural factor like chain length and copolymer also
influence Tm
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REFERENCES
• Polymer science and technology robert o. Ebewele
• Https://chat.Openai.Com/c/fce1e557-7c09-491f-a22c293caf4de643
• Chain length effect in polymer structure - search (bing.Com)
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THANK YOU FOR LISTENING!
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