onlinemetallurgy.com

1. ( effect of side group)
STRUCTURE-PROPERTY
RELATIONSHIP
Presented by :
MUHAMMAD UMAIR BUKHARI MME-09E-08

2. FOR MORE HELP CONTACT ME
Muhammad Umair
Bukhari
Engr.umair.bukhari@gmail.com
http://onlinemetallurgy.com

3. WHAT IS A POLYMER?
• A long molecule
made up from lots
of small molecules
called
• monomers.

4. For the Thermoplastics (polyethylene)
• Tensile strength
• Creep resistance
• Impact toughness
• Wear resistance
• Melting temperature
All increases with increase in average molecular weight or degree
of polymerization. As the average molecular weight increases, the
melting temperature increases that’s makes the processing more
difficult.
So, for the ease of polymer processing, we can use of bimodal
molecular weight distribution.
Relationship With Degree Of Polarization

5. POLYSTYRENE COFFEE CUP
• In certain applications
such as for the polystyrene
coffee cup ,
• It is important to insure that
the residual monomer
concentration is extremely
small because of the toxic
concerns.
polystyrene coffee cup

6. • In polyethylene, the linear chains easily rotate
and slide when stress is applied, and no stronger
polar bonds are formed between the chains
• Thus, polyethylene has low strength.
EFFECT OF SIDE GROUPS

7. Vinyl Compound
• One of the hydrogen atom is replaced with a
different atom or atom group.
• When R is chlorine in the side group, product is
• When the side group is CH3, product is
EFFECT OF SIDE GROUPS

8. • Addition of the benzene ring as a side group gives
• CN group produces

9. Vinylidene compound
• When two of the hydrogen atoms are replaced, the monomer is
a vinylidene compound
• Examples:
 Polyvinylidene Chloride
 Polymethyl Methacrylate
EFFECT OF SIDE GROUPS
P M M A L e n s
Po l y m e t hy l m e t h a c r y l a t e

10.  Larger atoms such as chlorine or groups of atoms such as
methyl and benzene make it more difficult for the chains to
 Rotate
 Uncoil
 Disentangle
 Deform by viscous flow
under the high temperature and applied stress.
This condition leads to
• Higher strength
• Higher stiffness
• Higher melting temperature
EFFECT OF SIDE GROUPS

11. • The chlorine atoms are strongly attracted by hydrogen
bonding to hydrogen atom on adjacent chain.
This is the reason why PVC is more rigid than many
other polymers.
• When low molecular weight compounds such as
plasticizer are added to PVC , the glass temperature is
lowered.
• This make PVC more ductile and workable and known
as vinyl.
EFFECT OF SIDE GROUPS

12. Polytetrafluoroethylene
• In Polytetrafluoroethylene all four hydrogen atom in the
polyethylene structure are replaced by fluorine.
• Strength is not much greater than that of polyethylene.
• C-F bond permits PTFE to have high melting point.
• Low friction non-stick characteristic that make the polymer
useful for bearings and cookware.
• Branching reduce the density stiffness and strength of the
polymer.
EFFECT OF SIDE GROUPS

13. Any
Question
? ? ?