Post on 22-Jun-2015
transcript
LOGO
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.
LOGO
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.