PBO (polybenzoxazole) is a synthetic fiber known for its high strength and thermal stability. It is synthesized through condensation polymerization and spun through a dry-jet wet spinning process. PBO has excellent tensile strength and modulus even at high temperatures, along with good chemical and flame resistance. Common applications of PBO fiber include body armor, motorsports safety equipment, aircraft and spacecraft components, and high-altitude science balloons, due to its lightweight and durable properties.

1. SUBMITTED TO :- SUBMITTED BY:-
A K GANGWAR SIR AKASH
KANOJIA
DR. MUKESH KUMAR SINGH SIR VIKASH SHEEL
DR.D.B. SHAKYAWAR SIR ANKUR VISWAKARMA

2.  Introduction of PBO polymer
 Classification of PBO polymer
 Key Features of PBO polymer
 Structure of PBO polymer
 Raw material of PBO polymer
 Basic properties of PBO polymer
 Manufacture of PBO polymer
 Usage of PBO polymer

3.  PBO(polybenzoxazole) was first
developed in the 1980’s by TOYOBA
Corp. Ltd., JAPAN and is the world’s
strongest man-made fiber. It is also
the first organic fiber whose cross-
sectional strength outperforms both
steel and carbon fiber.
 IUPAC Name - poly(p-phenylene-2,6-
benzobisoxazole)

4. Polybenzazoles polymers can be classified
into two categories-
1. PBO ( polybenzoxazole )
2. PBT ( polybenzothiazoles )
Note :- These two polymer is the formation
of the benzothiozole and benzoxazole
ring structures.

6.  Excellent thermal stability
 Excellent strength & modulus
 Good flame resistance
 Excellent creep resistance
 Good chemical resistance
 PBO is a rigid-rod isotropic crystal
polymer that is spun by a dry-jet wet
spinning process

8.  PBO is synthesized by condensation
polymerization of 4,6-diamino-1,3-
benzenedoldihydrochloride (DABCO)
with terephthalic acid (TA) at 60-80°c.

9.  P B O fiber is the next generation
super fiber with strength and modulus
almost doubles that of p-Aramid fiber.
P B O shows 100 ° C higher
decomposition temperature than p-
Aramid fiber. The limiting oxygen
index is 68, which is the highest among
organic super fibers.

10. ZYLON®AS ZYLON®HM
Filament Decitex 1.7 1.7
Density (g/cm3) 1.54 1.56
Tensile Strength (cN/dtex)
(GPa)
(kg/mm2)
3.7
5.8
590
3.7
5.8
590
Tensile Modulus (cN/dtex)
(GPa)
(kg/mm2)
1150
180
18000
1720
270
28000
Elongation at break (%) 3.5 2.5
Moisture regain (%) 2.0 0.6
Decomposition Temp. (°C) 650 650
LOI 68 68
Thermal expansion coefficient _ -6×10⁻6

12.  PBO is synthesized by condensation
polymerization of
4 , 6- diamino - 1 , 3 – benzenedoldihydrochloride (
DABCO ) with terephthalic acid (TA) at 60-80 °C.
 The polymerization is carried out in poly (phosphoric)
acid (PPA) solvent and molecular weights of about
50000-100000 g/mol corresponding to about 200-400
repeat units per chain are obtained.
 In synthesis of PBO, PPA plays a role as a solvent as
well as catalyst and dehydrating agent.

14. These polymers decompose at high temperatures without
melting and are soluble in very few solvent systems due to their
rigid molecular backbone.
 PBO is soluble in strong protonic acids such as PPA,
methane sulfonic acid (MSA), chlorosulfonic acid, and
trifluoroacetic acid via backbone protonation, which weakens
intermolecular interaction.
 PBO fibres are prepared using 13-17% solid content in poly-
phosphoric acid solution at 60-90 °C. The structure formed
during coagulation shows a network of oriented microfibrils.
 Heat treatment at 450-500 °C for one minute under tension
results in about eight times and 10-20% improvement in modulus
and strength, respectively.

15.  Improvement in overall axial orientation, crystal perfection and
improved mechanical properties.
 The mechanical properties of PBO fibre depend on polymer
molecular weight, as well as on processing and post processing
conditions.
 PBO fibres should be stored in low RH environment because
PBO tensile strength also drops sharply with UV exposure in the
initial stage, which indicates that the products of PBO fibre for
outdoor use have to be protected from the UV radiation.
 PBO staple fibre showed low resistance under acid and base at
high temperature.

16. 1. BODY ARMOR
Zylon gained wide use in U.S. police officers body
armor protection in 1998 with its introduction
by Second Chance Body Armor, Inc.

17. 3. Motorsport
As has been the case since 2001, Zylon tethers are used
in Formula One to affix the wheel to the chassis for
preventing the wheel.
In 2011, a Zylon strip was introduced to reinforce the top of
the racing helmet visor/front part.

18. 3. Standing rigging
On modern racing yachts Zylon is used
for parts of the standing rigging. It is
used as shrouds and stays in racing
yachts.

19. 4. Conductive textile
Zylon has been incorporated as the
base fiber for some conductive textiles,
where the Zylon fiber is plated with
nickel, copper, silver, or gold.

20. 5.HIGH-ALTITUDE BALLOON SCIENCE
Zylon is used by NASA in long-duration, high-
altitude data collection. Braided Zylon strands
maintain the structure of PE superpressure balloons.
Zylon is the material of choice due to its low weight,
high tensile strength and thermal properties.