Post on 25-Jun-2015
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