List of Polymer Matrix Composites | Materials

The following are the list of polymer matrix composites: 1. Glass Fiber Reinforced Plastic (GFRP) Composites 2. Carbon Fiber Reinforced Polymer (CFRP) Composites 3. Aramid-Fiber Reinforced Polymer Composites 4. Metal Matrix Composites 5. Ceramics Matrix Composite 6. Carbon-Carbon Composites (CCC) 7. Hybrid Composites 8. Structure Composites.

1. Glass Fiber Reinforced Plastic (GFRP) Composites:

It consist of glass fibers in a polymer matrix. It is produced in largest quantities. Glass is drawn into fibers of diameter range between 3-20 mm.

Glass is popular as reinforcement material as:

i. It is easily drawn into fibers from the molten state.

ii. Readily available and economical to fabricate

iii. Wide variety of composite manufacturing technique can be used.

iv. It produces composites of very high specific strength.

v. When combined with polymer matrix it possesses a chemical inertness that renders the composite useful in variety of corrosive environments.

Newly drawn fibres of glass are coated during drawing with a ‘size’ a thin layer of substance that protects the fiber surface from damage and undesirable environmental interactions.

This size is removed prior to composite fabrication and replaced with a “coupling agent” that promotes bond between the fiber and matrix.

These materials have high strengths but lack rigidity and stiffness required for some applications (e.g. structure of aeroplane and bridges). Services temperature is limited to 200°C as at high temperature polymer begins to flow.

Applications:

Automotive and marine bodies, plastic pipes, storage container, industrial floorings, transportation industries etc.

2. Carbon Fiber Reinforced Polymer (CFRP) Composites:

Carbon as a fiber phase has following advantages:

i. Carbon fibers have highest specific strength and specific modulus among all reinforcing fiber materials.

ii. Retain their strength and modulus at elevated temperature.

iii. At room temperature carbon fibers are not affected by moisture, bases, acids etc.

iv. Composite properties can be engineered according to applications.

v. Manufacturing processes are relatively inexpensive and cost effective.

vi. Here, carbon fibers are represented by both graphite and non-crystalline regions. Polymer matrix materials are rayon, poly acrylonitrile (PAN) and pitch.

vii. Carbon fibers are normally coated with a protective epoxy size that also improves adhesion with the polymer matrix.

Application:

Extensively used in sports and recreational equipment (fishing rods, golf clubs), filament wound rocket motor, cars (pressure vessels and air craft structural components) both military and commercial, helicopters (wing, body etc.).

3. Aramid-Fiber Reinforced Polymer Composites:

They are desirable for their outstanding strength to weight ratio.

Chemically, this group of materials is known as poly paraphenylene terephthalamide.

Two most common aramid materials are Kevlar & Nomex.

The rigid molecule are arranged in the direction of fibre axis.

These fibers have high longitudinal tensile strength & moduli.

However, these are relatively weak in compression. In addition, aramid have high resistance to creep and fatigue failure.

They are stable at higher temperatures (-200°C to 200°C).

Chemically they are susceptible to degradation by strong acid and bases.

Typical applications are Bullet proof vests, sporting goods, ropes, missile cases, automotive brake and clutch lining gaskets etc.

4. Metal Matrix Composites:

It is a matrix of ductile metal.

Further, the reinforcement may improve stiffness specific strength, resistance to abrasion, creep resistance and dimensional stability.

Advantage of MMC over PMC include higher operating temperature, non-flammability and resistance to degradation by organic fluids.

Alloy of Al, Cu Ni, Titanium are employed as matrix materials, Reinforcement may be in the form of particulates, continuous or discontinuous fibers and whiskers.

Concentration normally range between 10 to 50%.

Cermets fall under the MMC category.

Some MMC are reactive at elevated temperature, which may cause degradation at high temperature processing. This problem is resolved by a protective coating to the reinforcement.

Processing of MMC’s involve synthesis followed by shaping operations. Discontinuous fiber MMC’s can be shaped by standard metal forming operations (forging, extrusion, rolling).

Application:

Engine component, extruded stabilizers, forged suspension and transmission component, space shuttle structure etc. Super alloy (Ni & Co) based alloys matrix are used to counter high temperature creep in gas turbine engine etc.

5. Ceramics Matrix Composite:

Here particulates, fibers or whiskers of internal toughness of ceramic are embedded in the matrix of other ceramic.

This improves the internal toughness of ceramic.

This improvement in fracture toughness properties results from interaction between advancing cracks and dispersed phase particles.

One such technique is “transformation toughening”.

Small particles of partially stabilized zirconia are dispersed within the matrix material phase at ambient condition allow retention of the metastable tetragonal phase at ambient conditions rather than stable monoclinic phase.

The stress field in front of the propagating crack causes these metastable tetragonal particles to undergo transformation to stable monoclinic phase.

Accompanying this transformation in a slight particle volume increase and the net result is that compressive stresses are established on the crack surface near the crack tip that tends to pinch the crack shut, thereby arresting its growth.

Ceramic whiskers also inhibit crack propagation by:

(i) Deflecting crack tips.

(ii) Forming bridges across crack forces.

(iii) Absorbing energy during pull-out as whiskers deboned from the matrix.

(iv) Causing redistribution of stresses in the region adjacent to crack tips.

CMC’s have high creep resistance and thermal shock resistance. CMC’s are fabricated by hot pressing, hot isotactic pressing and liquid phase sintering techniques.

Used as cutting tool inserts for machining hard metal alloys with tool life greater than cemented carbides.

6. Carbon-Carbon Composites (CCC):

It is a carbon fiber reinforced carbon matrix composite. These have high tensile strength and moduli that are retained at temperature above than 2000°C.

High resistances to creep, and relatively large fracture toughness.

These are highly resistant to thermal shocks.

Their major drawback apart from being expensive is that they are susceptible to oxidation at high temperature.

Application:

CCC find application in rocket motors, friction materials in aircraft and high performance automobiles, hot pressing moulds, components of turbine engines and as ablative shields for re-entry vehicles.

These are expensive because of complex processing techniques. Carbon fibers formed are impregnated with a liquid polymer resin. The work pieces is then formed into final shape and the resin is allowed to cure.

Now, the part is heated in an inert atmosphere where molecular components consisting of oxygen, hydrogen and nitrogen are driven off, leaving behind large carbon chain molecule. Subsequent heat treatments at higher temperature will cause the carbon matrix to density and increases in strength.

Fibers in resin → forming → pyroluses → Heat treatment → Matrix become dense and strengthened.

7. Hybrid Composites:

Glass fibers + Carbon fibers. First carbon fibers will fail and then load is taken by glass fibers and matrix. Typical application are sports goods and orthopaedic components.

Types of Hybrid Composite:

(i) Interply hybrid (alternate lamina of some matrix different fibers)

(ii) Intraply hybrid (contains each lamina having two or more kinds of fibres system)

(iii) Interply – Intraply – combination of both

(iv) Super hybrid

Applications:

(i) Antenna dishes of CFRP and aluminium honeycomb.

(ii) CFRP & GRP used in leaf & springs and device shaft of automobile.

(iii) Helicopter rotors and thin-walled tube of CFRP & GRP.

(iv) Artificial limb and external bearing made of CFRP. S.Squash and galf club raequets with shafts made of CFRP/GRP/Wood hybrid.

8. Structure Composites:

i. Sandwich Panels:

These consists of two strong outer sheets, or faces separated by a less dense material, or core which has lower stiffness and lower strength.

The faces bear most of the in plane loading and also any transverse bending stresses. Typical face materials include aluminium alloys, fiber reinforced plastics, steel and plywood.

The core serves two function first is separates the two faces and resists the deformation perpendicular to the face plane.

Secondly, it provides certain degrees of shear rigidity along planes that are perpendicular, synthetic structures are sandwiched between face panels.

These found wide variety of application one such as roofs, floors, walls of buildings, aircraft wings.

Sandwich composite is constructed by sandwich foam between two skins of FRP laminates.

The thickness of skin is kept upto 3 mm and thickness of core is kept deeper.

The core is either foamed or made of honeycomb material.

As thickness of core is deep, the area moment of inertia of cross-section is enhanced too much, leads to increase in flexure rigidity of sandwich beam which make it suitable to use as beam.

In this core of self-supporting skin sandwiched between layers of carbon fiber tape impregnated with an epoxy resin, had honey combed paper like material threaded with fibres.

Its composite air craft except engine

ii. Laminated Composite:

These are mode of many laminae. Lamina also known as ply or a layer is very thin, about 0.1mm to 1mm thick. These are glued or joined together to form a laminate of desired thickness. Number of lamina in a laminate can be few to many tens.

Examples:

a. Plywood

b. Metal to metal laminate (cladded metal)

c. Sheet moulding compounds

d. BMC

e. Linoleum

f. Tufnol