LIQUID CRYSTAL

POLYMERS

LIQUID CRYSTAL POLYMER

• These polymers which have a tendency to allign their chains parallel over a long distance , prior to the crystallization from their melt or solution.

• Occurrence: Liquid crystallinity in polymers may occur either by dissolving a polymer in a solvent or by heating a polymer above its

glass or melting transition point.

TYPES OF LCPs

Lyotropic LCP

Thermotropic LCP

Formed from their solution.

Formed from their melt.

CONDITIONS

• Highly polarised chain structure.

• Molecules should have aromatic rings.

• Molecules should be like disc.

Disc like structure

MISCELLAENOUS

• Liquid-crystal polymers (LCPs) are a class of aromatic polyester polymers.

• Polyester Polymers: Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most

commonly refers to polyethylene terephthalate (PET).

Preparation

PROPERTIES

• Higher crystallinity in solid state.

• High tensile strength.• Very tough.• Higher Tm and Tg.• Have property of

multiple internal reflection.

• Used at higher working

temperature.

APPLICATIONS

• For optical fibres.• Electrical and electronics

app.• Transport,automotive,mil

itary app.• Aircraft and aerospace

app.• Chemical and consumer

app.

• Used as fillers for composites.

KEVLAR

• Kevlar is the registered trademark for a para-aramid synthetic fiber.

• This high strength material was first commercially used as a replacement for steel in racing tires.

• Typically it is spun into ropes or fabric sheets that can be used as such or as an ingredient in composite

material components.

PREPRATION

Tere phthalic acid dichloride

1,4 diaminobenzene

Monomeric Unit

PROPERTIES

• Has a tensile strength of about 3,620 MPa.

• A relative density of 1.44.• 5 times stronger than steel.• Although it has high melting

point, it can be easily moulded.

• It has high heat stability.

OTHER PROPERTIES

• It is slightly stronger at low temperatures.• At higher temperatures the tensile strength is

immediately reduced by about 10–20%.• After some hours the strength progressively

reduces further.

USES

• Used for aerospace applications and aircraft industry.

• Used for puncture resistant tyres.

• Making ropes and cables.• Bulletproof vests and

helmets.

OTHER USES

• Used in sports equipments.

• Particle physics.• Some fire dancing

props.