- Glass fiber is an inorganic fiber which is neither orientated nor crystalline. It is composed of silicon dioxide (sand) and variety of metal oxides such as calcium dioxide, boron dioxide, aluminum oxide and a few more.
- Different glass fibers types are commercially available which have different compositions and technical significance. Some of the popular glass varieties are A glass, AR glass, C glass, E glass, HS glass which refers to high strength glass.
- For manufacturing of glass fiber two methods aare used namely, Marble melting process and Direct melt process.
Marble Melting Process:
It
involves preparation of marbles, which are melted in the fiberisation stage.
Direct Melting Route:
- In this process, the furnace is fed continuously with raw materials which are melted and refined. Melted glass reaches the bushings from which the fibers are drawn.
- The glass fiber is produced by rapid attenuation of molten glass exuding through nozzles under gravity. Bundle of fibers known as roving are produced by assembly multiplies of 200 filaments into the required size of roving.
- Direct roving can also b formed into a final package. Over 90%of all continuous glass fibers are produced are ‘E’ glass which has reinforcement application in Glass reinforced plastic (GRP).
Properties of Glass fibers:
- Not affected by water, has virtually no shrinkage
- It is fire proof
- Has excellent ignition resistance
- It is higher in strength than steel of the same diameter
- Resistant to sunlight, mild dew, bleach and other chemicals
- Causes irritation if broken fibers penetrates inside skin
Applications of Glass Fibers:
- Glass fiber reinforcement composites for aircraft and aerospace, appliance and equipment, construction, consumer goods, corrosion resistant products,
- Tyre reinforcement
- Optical fibers: made from extremely pure silica produced under finely controlled process conditions. Used in communication as telephone, television networks in air crafts and satellite communication.
Carbon
Fiber :
Properties
of carbon fiber:
- It has ability to from different structures
- It has super high tensile strength, ignition resistant as well as temperature resistant
- It is electrically conductive
- It can be woven and fabricated as non- woven textile
- Range of structure includes, amorphous carbon, activated carbon, carbon black, graphite, diamond
Applications
of Carbon fiber:
- It is most widely used as precursors for producing carbon fibers like Polyacrylonitrile (PAN), cellulosic fibers (Viscose Rayon, cotton etc)
- It is used in rotor blades, ship keels
- The main popular use in Aerospace industry is because it is about 5 times as strong as most metals with respect to tensile strength and 7 times as strong as most metals with respect to specific strength and weight
Carbon Fiber Manufacturing From PAN (Polyacrylonitrile):
- The polyacrylonitrile is wet spun and stretched to form a PAN filament
- The Pan filament is carbonized by heating at 1000-2000 degree Celsius in an inert atmosphere for about 30 minutes
- Then this forms relatively low modulus, carbon fibers
- After the carbon fibers are from it is followed by graphitization which involves heating above 200 degrees with or without stretching. If the carbon fibers are stretched then it forms high strength carbon fibers
Ultra-fine
Fibers Or Micro Fibers:
- These are the fibers with linear density less than 1.0 dtex
- It was first introduced by Japanese in attempt to reproduce silk like properties with the addition of enhanced durability
- They are usually made from polyester and nylon polymer
- They are developed to obtained light weight, soft water proof fabrics that eliminate the conventional coating or lamination
- There are three manufacturing processes involved in the production of micro fibers which are Island-in-sea, melt spinning and split spinning
Split
Technique micro fiber:
Contains
bicomponent filament containing two types of polymer spun and split by
mechanical or physical means. It imparts sharp angled edges that act as gentle
abrades in wiping clothes used by optical and precision micro- electronic
industries.
Island-In-Sea:
In
this method, two polymers are considered, soluble polymer ‘A’ and insoluble
polymer ‘B’ and these polymers are extruded through melt spinning. The polymer
‘A’ forms matrix and polymer ‘B’ forms fibrils. After spinning, polymer A
dissolves leaving the fibrils of insoluble polymer B.
Applications
of Micro- Fibers:
Woven
fabric form, due to fine diameter, tight weaves is obtained, making them
impermeable to water droplets while allowing air and moisture vapor
circulation.
Low
diameter and compact packing makes it beneficial in production of barrier
fabrics in the medical industries
Hollow
Fibers:
Properties
of Hollow Fibers:
- Light weight
- It is heat insulating material
- It is produced by specially designed spinneret
- Provides small heat conductance
- Apparent density is less than one due to hollowness
Applications
of Hollow Fibers:
- It is used in water purification (micro filtration)
- Ultra-fine filtration
- Artificial kidney(Dialysis)
- Used in swimming costumes and Artificial liver
Aramid
Fibers:
They
are chemically similar to nylon containing amide groups and are aromatic
polyamide. There are two types Meta- Aramid and Para- Aramid.
Properties
of Meta- aramid fiber:
- High temperature resistant
- It has moderate tenacity
- It has low modulus
- Excellent resistant to heat
- It has high melting point around 600 degree Celsius
Properties
of Para- Aramid (Kevlar):
- Has high strength and high modulus
- Good resistant to acid and strong bases
- Inherently ignition resistant
- Excellent dynamic energy absorbing properties
- Outstanding high temperature dimensional stability
Applications
of Aramid Fibers:
- Reinforcement material in composite structure
- Industrial and consumer application such as filter cloth, ropes, cords
- High temperature properties as splatter resistance clothing
- Protective application such as ballistic protection (helmet shells, armor vests, armor plates etc).
0 Comments