The document discusses crystallinity in polymers. Crystallinity affects the optical, mechanical, thermal and chemical properties of polymers and can range from 10-80% depending on the polymer, making them semi-crystalline. A polymer's structure and intermolecular forces influence its ability to form crystals. Crystallinity can be estimated using different analytical methods like x-ray scattering, dilatometry, and comparing crystalline and amorphous peak areas. Crystallinity contributes to the strength of many polymeric materials.

1. POLYMER SCIENCE
TOPIC : CRYSTALLINE IN POLYMER
MD. FEROZ AL MAMUM

2. CRYSTALLIZATION OF POLYMERS
Crystallization affects optical, mechanical, thermal and chemical
properties of the polymer. The degree of crystallinity is estimated by
different analytical methods and it typically ranges between 10 and
80%, thus crystallized polymers are often called "semi-crystalline".

3. CRYSTALLINITY AND POLYMER STRUCTURE
A polymer's structure affects crystallinity a good deal. If it's regular and
orderly, it will pack into crystals easily. If it's not, it won't. It helps to
look at polystyrene to understand how this works.

4. CRYSTALLINITY AND INTERMOLECULAR FORCES
Intermolecular forces can be a big help for a polymer if it wants to
form crystals. A good example is nylon. You can see from the picture
that the polar amide groups in the backbone chain of nylon 6,6 are
strongly attracted to each other. They form strong hydrogen bonds.
This strong binding holds crystals together. This raises the melting
point compared to polymers without strong intermolecular
interactions, like polyethylene

5. CONFINED CRYSTALLIZATION
When polymers crystallize from an isotropic, bulk of melt or
concentrated solution, the crystalline lamellae (10 to 20 nm in
thickness) are typically organized into a spherulitic morphology as
illustrated above.

6. DILATOMETRY
DILATION OR CHANGE IN SPECIFIC
VOLUME COMPUTING CRYSTALLINITY
Liquid of
known density
and thermal
expansion
coefficient
Polymer
∆V
ecrystallintotallyamorphous
ecrystallinpartiallyamorphous
vv
vv
C
−
−
=%

7. Example: Nylon
How would you
find the density
(i.e. specific
volume) of this
crystal given the
size and shape?
DILATOMETRY
ecrystallintotallyamorphous
ecrystallinpartiallyamorphous
vv
vv
C
−
−
=%
Youyong Li and, William A. Goddard III
Macromolecules 2002 35 (22), 8440-8455

8. X-rays: light with
wavelength ~0.1-
10Å – the same
length scale as
interatomic
distances
Diffraction occurs
only at specific
angles, given by
the Bragg eqn.
WIDE ANGLE X-RAY SCATTERING/DIFFRACTION
θλ sin2dn =

9. X-RAY SCATTERING CRYSTAL PLANES
θλ sin2dn =

10. Polycrystalline
samples look
different.
Example: Highly
crystalline
polymer with
(mostly) oriented
crystallites.
Diffraction spots
are blurred into
lines.
WHAT IF IT’S NOT A SINGLE CRYSTAL?

11. Diffraction
circles become
much less
defined and
blurred.
Sharpness of
circles gives a
clue to
crystallinity.
WHAT IF IT’S NOT CRYSTALLINE?

12. The crystallinity
can be estimated
by comparing the
areas of the peaks
due to the
amorphous polymer
with those of the
crystalline phase:
%C=Acr / (Acr +
Aam)
AN ESTIMATE OF CRYSTALLINITY
K.A. Moly et al. / European Polymer Journal 41
(2005) 1410–1419;

13. EXAMPLE: STRAIN-INDUCED CRYSTALLIZATION
S. Toki et al. / Polymer 41 (2000) 5423–
5429

14. CONCLUSION
Offshoot: A combination of methods may be the best solution (e.g. x-ray
scattering, DSC)
Polymer crystallinity contributes to the strength of many polymeric
materials.
Questions?

15. REFERANCE
 https://en.wikipedia.org/wiki/Crystallization_of_polymers
 http://pslc.ws/macrog/crystal.htm
 https://en.wikipedia.org/wiki/Crystallization_of_polymers#Crystalliza
tion_mechanisms
 http://encyclopedia2.thefreedictionary.com/crystalline+polymer
 Polymer Engineering and Science , September, 1969 , Vol. 9 No. 5