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PBO fibers (ZYLON)

INTRODUCTION:

In the 1970s, DuPont reported that extended chain, all para-aromatic polyamides (‘aramids’) gave high strength, high modulus fibres when processed from liquid crystalline solutions.

The ability greatly to increase the order in the liquid crystalline state, compared to conventional polymer solutions, offered an excellent opportunity to design and process new Para-ordered polymer systems for fibre-reinforced composites.

نیروی هوایی پایگاه Wrightتحقیقات وسیع در مرکز تحقیقات

Patterson ب�ا خ�واص اس�تحکامی و ح�رارتی الی�افی تولی�د جهت

ه�ترو حلق�وی آروماتی�ک سیس�تمهای روی ب�ر وی�ژه، بس�یار

سیکلیک، با ساختار پارا متمرکز گردید.

A heterocyclic compound is a cyclic

compound that has atoms of at least two

different elements as members of its ring(s).

pyran

pyridine

One class of heterocyclic polymer system

that could meet all the harsh requirements

for advanced aircraft and aerospace

applications and could be obtained in the

form of fibres was the benzobisazole

materials, which have five-membered

rings on either side of benzene rings.

Poly(p-phenylene benzobisoxazole)

(PBO) and poly(p-phenylene

benzobisthiazole) (PBT) have

received the most attention.

Manufacture of PBO fibres

4,6-diamino-1,3-benzenediol dihydrochloride

poly(phosphoric) acid (PPA)

Stoichiometric amounts of amine and TA are heated in 77% PPA at 60–80 °C for the dehydrochlorination of the amine monomer.

The temperature is lowered to 50 °C and P2O5 is added to obtain the high degree of polymerization (between 82–84%).

Rigid rod polymers decompose at high temperatures without melting and can be dissolved in very few solvent systems owing to their aromatic structure and to their rigid molecular backbone.

Spinning

Conventional melt-spinning and

solution-spinning technologies

cannot therefore be used.

These fibres, however, can be spun

from solutions in PPA via the dry-jet

wet-spinning technique,

What is PPA?

The term polyphosphoric acid refers to concentrated grades of phosphoric acid (H3PO4) above 95%.

At these high concentrations, the separate phosphate units are polymerized. 

2 H3PO4 → H4P2O7 + H2O

This involves extrusion of polymer solution (liquid crystalline phase) under heat and pressure through an air gap into a coagulating bath (generally water at room temperature), followed by washing, drying, and finally heat treatment.

Heat treatment is usually carried out

in the 500–700 °C range under

tension, in nitrogen, for between a

few seconds and a few minutes.

الیاف تولیدی دارای ساختار فیبریلی و میکروفیبریلی بسیار آرایش یافته می باشند.

ZYLON

شرکتTOYOBO الیاف تهیه شده ازPBO را

به بازار ارایه نموده ZYLONبا نام تجاری

است.

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Fiber Properties

ZYLON® (PBO fiber) is the next

generation super fiber with strength

and modulus almost doubles that of

p-Aramid fiber.

Mechanical properties

Mechanical properties

Thermal properties

ZYLON® shows 100°C higher decomposition temperature than p-Aramid fiber.

محدوده دمای تخریب حرارتی این الیاف بین درجه است.۶۰۰-۷۰۰

The limiting oxygen index is 68, which is the highest among organic super fibers.

Thermal properties

A significant difference of weight loss behavior is observed at 500°C between ZYLON® and Aramid fibers.

The strength of ZYLON® gradually decreases even at the temperature of less than 100°C in high humidity condition. ZYLON® fiber should be stored free from high humidity at normal room temperatures.

Hot air shrinkage

Flame resistance

ZYLON® shows extremely high flame resistance. In a vertical flame test (JIS L1091 A-4), char length is almost zero.

Light resistance

Chemical resistance

Exposure to strong acids causes strength losses. However, ZYLON® is more stable than p-Aramid.

ZYLON® is stable to alkaline at room temperature. NaClO (bleach) does not cause strength loss for ZYLON® at room temperature.

Abrasion resistance between fiber and metal

Applications

The applications of PBO fibres are vast owing to

the excellent properties mentioned previously.

PBO fabrics are light and flexible, providing

improved comfort and mobility, and are ideal for

heat and flame resistant work-wear such as for

fire fighters.

Motorcycle suits have particular areas,

such as the knee and elbow regions,

reinforced with PBO fabric, providing the

required excellent heat, flame and

abrasion resistance.

As with aramids, PBO is ideal for ballistic-protection fabrics and panels owing to its high energy absorption and rapid dissipation of impact by the fibrillar morphology.

General applications for reinforcement include those for tyres, belts, cords, etc., as well as for optical fibre cables.