2015-01-15 09:11:28

What is the prepreg and its benefits

What is a Prepreg?

Prepregs are composite materials in which a reinforcement fiber is pre-impregnated with a thermoplastic or
thermoset resin matrix in a certain ratio. Prepregs have unique properties as they are cured under high
temperatures and pressures.Generally, the resin matrix in prepregs is partially cured for ease of handling
and is stored in a cool place to prevent complete polymerization. This B- stage prepreg will need to be
heated in an autoclave or oven during manufacture of composite materials to achieve full polymerization.
The reinforcement in a prepreg can be unidirectional fibers or a fabric.

How are Prepregs Manufactured?

Prepregs are produced using two main processes: hot melt process and solvent dip process.Hot Melt
Process Both fabric and unidirectional prepregs can be produced using the hot melt process. There are two stages in this process. The first stage involves coating a thin film of the heated resin on a paper substrate.
The reinforcement material and the resin are allowed to interact in the prepreg machine. On application of
pressure and heat, the resin is impregnated into the fibre resulting in the final prepreg, which is ultimately
wound on a core.Solvent Dip Process Only fabric prepregs can be produced using the solvent dip process,
which involves dissolving the resin in a solvent bath and dipping the reinforcing fabric in the resin solution.
Using a drying oven, the solvent is then evaporated off the prepreg.Benefits of Prepregs The major
advantages of using prepregs are listed below:
Ease of use Low void content
Good fatigue resistance
Control of laminate thickness
Good environmental and corrosion resistance
Control of fibre volume fraction
Clean process
Better conformity and quality
High specific modulus and strength
Very low thermal expansion coefficient
Enhanced vibration damping characteristics

Applications of Prepregs

Prepregs are being increasingly used in high performance applications in the composites industry and also in other sectors. Some key areas where prepregs currently find use are listed below:

Aircraft interiors, aerospace components, aircraft flooring, cargo liners Automotive parts and components,
tooling, ballistic panels A/C ducting, electronic-transmission applications,UV resistant parts, sporting goods,
high temperature parts Honeycomb and foam panels, flame retardant laminates,Carbon-carbon composites, high-rise flooring, high impact surfaces,UAVs, seatbacks, doublers The discovery of novel material formats
have gone a long way in de-mystifying prepregs, speeding up their acceptance and decreasing their costs.
As environmental concerns promote interest in new processes that replace wet lay-up, one ideal alternative can be low temperature prepreg.