SHORT AND LONG

FIBERS Presented By,SHILPA SIMONII M.Sc BIOPOLYMER SCIENCE

CLASSIFICATION OF COMPOSITES

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CONTINUOUS DISCONTINUOUS

Fibre composites consist of matrices reinforced by short (discontinuous) or long (continuous) fibers.

FIBRE REINFORCED COMPOSITES

(a)Unidirectional (b) Cloth (c) Roving

(a) (b) (c) (a) (b)

(a) Chopped (b)Mat

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SHORT AND LONG FIBRE.

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SHORT FIBRE

• It consist of a matrix , reinforced by a dispersed phase in the form of discontinuous fibers.

• Short fibers are divided into 1. Aligned 2. Randomly oriented

• Fibre length is in the range of 2 to 4mm

• Examples: Glass fibre, Carbon fibre

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PROPERTIES OF SHORT FIBERS • Mechanical properties of short fibers depends on

Fibre Length Distribution (FLD ) Fibre Orientation Distribution (FOD )

• Adding short fibre to thermoplastic resin improves the composite performance for light weight applications

• Increase in aspect ratio can affect strain value (low)

• Aspect ratio(s) = length/diameter (5 to 500)

• Processing techniques Injection moulding Extrusion Spray-up(chop)

• ApplicationsElectrical & ElectronicsAutomotivesOil fieldChemical processDefense industriesSwimming pool

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LONG FIBRE

• It consist of matrix , reinforced by a dispersed phase in the form of continuous fibre• Long fibers are classified as

1. Unidirectional orientation 2. Bidirectional orientation• Fibre length is in the range of 10 to 12mm• Examples : Asbestos is the only naturally occurring long mineral fiber .

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Advantages of long fibre

• Improved impact

• Safer impact mode

• Reduced warpage

• Improved creep resistance

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•Processing techniques Injection moulding

Compression moulding

•Applications Aerospace industry Building envelope components such as windows and doors Automotive Aircraft parts

The main Troubleshooting during processing

o void formation Processing condition Fibre concentration Fibre length Cooling rate(slow cooling rate decrease void content in the composite)

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SHORT FIBRE LONG FIBRE Fibre length 2 to 4 mm Fibre length 10 to 12 mm

Processing technique – Injection moulding , Extrusion moulding , spray – up(chop)

Processing techniques – Injection & Compression moulding

Easier & cheeper to produce Low cost per part, enabled LFRT to replace metal part

Lesser void content Higher void content

aspect ratio is between 5 and 500 aspect ratio is between 200 and 500.

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