Crystallisability in polymer

it is a presentation on crystalisability and factor effecting it .

1. Department of Nano Science and Materials , Central university of jammu,J&K CRYSTALLLISABILITY AND FACTORS AFFECT By Lokanath mohapatra M.Sc. In Material Science & Tech. Guided By Dr. Pawan Kumar Assistant Professor

2. content : SOLIDS CRYSTALLINITY CRYSTALLISABLITY FACTORS AFFECTING CRYSTALLISABILITY

3. SOLIDS CRYSTALLINE SOLIDS : Crystalline solid is a solid material whose atoms or molecules are arranged in a regular, periodic manner .These are symmetrical. AMORPHOUS SOLIDS : An   A morphous solid  is any non-crystalline  solid  in which the atoms and molecules are in completely random pattern . These are unsymmetrical . Such solids  include glass, plastic, and gel.

4. CRYSTALLINITY Polymer exists both in crystalline and amorphous form. In polymer molecule part of molecules are arranged in regular order, these regions are called crystalline regions. In between these ordered regions molecules are arranged in random disorganized state and these are called amorphous region. Crystallinity is indication of amount of crystalline region in polymer with respect to amorphous content .

5. Polymer crystal structure

6. CRYSTALLISABLITY Crystallisabilty is the maximum crystallinity that a polymer can achieve at a particular temperature, regardless of the other conditions of crystallization .

7. Crystallisability at a particular temperature depends on a)Nature of the macromolecular chain   Harder the polymer greater the crystallinity Intermolecular forces b)Molecular weight and molecular weight distribution Narrow molecular weight, and high molecular weight increase the crystallinity.  c)Rate of cooling, d) Residance time, e) Temperature of molten polymer , f) rate of crystal growth,

8. Factor affecting crystallisability L inear polyethylene has highly regular configuration whose crystallinity 90% branched polyethylene has 40% crystallinity So it also depends on pattern of branching. 1 )Geometrical regularity:- a) linear and branched structure :-

9. b)Cis and trans position effect :- In cis isomer(natural rubber) banding in polymer chain so it gives a coiled structure But in trans isomer(gutta-percha) polymer chain it giving rod like structure So trans isomer is more crystalline.

10. c ) H omopolymer and co-polymer :- Homopolymer are highly crystalline Ex- linear polyethylene Alternating copolymer are crystalline Ex-chain of ethylene and propylene Random copolymer are not crystalline

11. 2) Polarity :- Nylon 6 is highly crystalline ,due to the polar group in the molecule which forms the hydrogen bond because of the hydrogen bonding adjacent chain are tightly poked .

12. 3)Bulky group :- When a polymer has bulky side group then it is very difficult to crystallise because the bulky side groups come on the way of close packing . in case of small side group polymer can be crystallise. Ex - in Polyvinyl carbazole crystallisation is difficult but Polyvinyl alcohol can easily crystallise as compare to polyvinyl carbazole . Polyvinyl carbazole Polyvinyl alcohol