Poly(vinyl carbazole) is known as a photoconductive material whose electrical conductivity increases with light exposure. It has good heat and chemical resistance and softens at 150°C. The monomer vinyl carbazole is prepared through a reaction of carbazole with acetylene and polymerized using initiators like di-tert-butyl peroxide. Poly(vinyl carbazole) is insoluble in many solvents and difficult to process, requiring high temperatures of 300°C for injection molding. Its main application is in electrostatic dry copying machines where it is used as the photoconductive layer in xerography.

1. POLY(VINYL CARBAZOLE)
Submitted By,
Vishal K P
semester 6
PS&RT
CUSAT
-SYNTHESIS, PROPERTIES & APPLICATION

2. INTRODUCTION
 They are known as Photoconductive materials, i.e., its
electrical conductivity increases with exposure to light.
 Polyvinyl carbazole has good resistance to heat and
chemicals.
 Softens at 150°C

3. STRUCTURE

4. PREPARATION OF MONOMER
 Vinyl carbazole is obtained by reacting carbazole with
acetylene.
 Readily available as a by product of coal tar distillation.
 Done in the presence of a catalyst and solvent under
pressure.
 The reaction would be carried out at 140°c in white spirit with
potassium carbazole as catalyst.

5. POLYMERIZATION
 High M.W polymers can be prepared by bulk polymerization
using Di-tert-butyl peroxide & 2,2-azobisdi-isobutyronitrile used
as initiators pressurized with N2 .
 Heating to 80-90°C causes an onset of polymerisation and a
rapid increase in temperature.
 After the maximum temperature has been reached the mass is
allowed to cool under pressure.

6. PROCESSING
 The polymer is not easy to process and in injection moulding
melt temperatures of 300°C are employed.
 In order to prevent excess embrittlement by shock cooling of
the melt, mould temperatures as high as 150°C may be used.
 The polymer may also be compression moulded at
temperatures of 250-260°C.

7. THE MOST IMPORTANT PROPERTIES OF POLY( VINYL
CARBAZOLE) ARE:
 Good photoconductivity
 A high softening
 High refractive index
 High brittleness
 Poly vinyl carbazole is insoluble in alcohol, esters,
ethers, ketones, carbon tetra chloride & caster oil

8. APPLICATIONS
 Earlier applications as a capacitor dielectric and other
electrical applications such as switch parts, cable connectors
and co-axial cable spacers are now very limited.
 The main application today for poly(vinyl carbazole) arises out
of its photoconductivity and is in electrostatic dry copying
machine.

9. XEROGRAPHY
 The polymer is applied from solution in thin film layers onto a
conductive substrate.
 In order to obtain the desired photoconductive characteristics,
toughness and adherence to the substrate various additives
are used.
 It is usual to incorporate additives such as electron acceptors,
plasticisers and primers.
 A typical electron acceptor is 2,4,7-trinitrofluoronone.

10. WORKING PRINCIPLE OF XEROGRAPHY
 When an electrostatic charge is applied to a coating in the dark
it is observed to discharge to an equilibrium value.
 When the light source is switched on, the conductivity is
increased and discharging occurs, leading to a negligible
charge.
 Which is then developed by a dry method by transferring the
charge onto a powder known as the toner.

11. OTHER APPLICATIONS
 The polymer may be regarded in these applications as a form of
photo resistor.
 It has been used in holography and in the manufacture of
printing plates.
 However, it has also been suggested for use in solar cells and
for measuring photoelectric resistance.

12. REFERENCES
 Conducting polymers & plastic by J Margolis ,Chapman
& Hall London 1993
 Plastics Materials by J A Brydson

13. THANK YOU