high modulus-high tenacity (HM-HT) fibres from linear polymers

1. Melt-spun wholly aromatic

polyester

2. PBO and related polymers

3. PIPD or ‘M5’ rigid-rod polymer

4. Russian aromatic fibres

5. Solid-state extrusion high-

molecular weight polyethylene

fibres

high modulus-high tenacity (HM-HT) fibres from linear polymers

Melt-spun wholly aromatic polyester

Thermotropic liquid crystal polymers

Introduction

• Liquid crystals (LCs) are a state of matter that

have properties between those of a conventional

liquid and those of a solid crystal.

• A very large number of chemical compounds are

known to exhibit one or several liquid crystalline

phases.

• For instance, an LC may flow like a liquid, but its

molecules may be oriented in a crystal-like way.

• Despite significant differences in chemical

composition, these molecules have some common

features in chemical and physical properties.

• There are many different types of LC phases.

• The various LC phases (called mesophases) can

be characterized by the type of ordering.

• The molecular shape should be relatively thin or

flat, especially within rigid molecular frameworks.

• The molecular length should be at least 1.3 nm.

• The structure should not be branched or angular

• Liquid crystals can be divided into thermotropic,

lyotropic and metallotropic phases.

• Thermotropic and lyotropic LCs consist of

organic molecules.

• Thermotropic LCs exhibit a phase transition into

the LC phase as temperature is changed.

• There are two types of thermotropic liquid

crystals: discotics and rod-shaped molecules.

• Discotics are flat disc-like molecules consisting of

a core of adjacent aromatic rings.

• Rod-shaped molecules have an elongated, anisotropic geometry which allows for preferential alignment along one spatial direction.

• Lyotropic LCs exhibit phase transitions as a

function of both temperature and concentration of

the LC molecules in a solvent

• Metallotropic LCs are composed of both organic

and inorganic molecules.

• Their LC transition depends not only on

temperature and concentration, but also on the

inorganic-organic composition ratio.

Vectra and Vectran

از • مهم TLCPیکی تجاری .VECTRAهای است

• This polymer is made by the acetylation

polymerisation of

• p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic.

• It is one of a family of naphthalene-based

thermotropic liquid crystal polymers

• No classical glass transition temperature is clearly

observed in the polymer, although molecular

transitions do occur with increasing temperatures.

• The commercially available TLCP fibre, VECTRAN,

is produced from Vectra LCP polymer.

Fibre production• TLCP fibre is melt spun using conventional

polyester extrusion practices.

• Wind-up speed is much lower, as is draw down, compared with PET processes.

• Some form of lubrication, either finish or water, is necessary for ease of processing, owing to the fibrillar nature of the fibre surface.

• Typical physical properties for the spun product

are 10 g/denier tenacity (0.9 N/tex), 2%

elongation, and 425 g/denier initial modulus (40

N/tex).

• This product represents a small percentage of the

total TLCP fibre sales.

• High strength, 23–28 g/denier tenacity (2–2.5

N/tex), is achieved in TLCP fibres by heat treating

in an inert atmosphere.

Fibre properties

الیWاف ویWژه TLCPالیWاف • تنهWا دارای خWواص اساسWی سWایر نWه

نظWیر اسWتحکام بWاال، ازدیWاد طWول تWا حWد پWارگی کم و مWدول بسWیار

نWیز منحصWربفردی برجسWته خWواص دارای بلکWه میباشWند زیWاد

هستند که مهمترین این خواص عبارتند از:

• 1- Fibre-to-fibre abrasion resistance:

• 2- Bending properties:

• 3- creep:

• 4- Cut resistance: TLCP fibres generally demonstrate excellent cut resistance, although this can be dependent upon the test used.

Applicaion