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What are Prepegs? Their Advantages and Disadvantages


What are Prepegs? Their Advantages and Disadvantages

  9 Apr 2019          Bhor Chemicals

“Prepreg” is a popular term for reinforcing a fabric which has been pre-impregnated with a resin system. This resin system already includes a proper curing agent. Resultantly, a prepreg is ready to get moulded without adding any more resin. In order for the laminate and cure, it is necessary to use a combination of pressure and heat.

Here we discuss the advantages and disadvantages of prepegs.

Advantages of Prepregs

There are many certainly many advantages of prepegs. Here are a few:

Prepegs have maximum strength properties. 

In a hand layup, it is tedious to achieve 50% resin content. It means that the completed laminate weight is 50% fabric and the rest is 50% resin. The typical hand laminates, even when they are vacuum bagged, end up with a efficient amount of excess resin. Excess resin adds up to the brittleness and reduces the overall properties. On the other hand, mostly the prepregs contain about 35% of resin. This is perfect for maximum cured properties and is generally impossible to achieve in normal lamination.

Prepegs give uniformity and repeatability. 

If there would be no pitfalls of human lamination techniques, then there will neither be resin-rich areas nor dry spots. The thickness of the ingredients will be uniform and each part that comes out of the mold has a likelihood of being identical. Although there is still a margin of error in the vacuum, bagging techniques, handling, etc., yet prepregs reduce these problems to a significant amount.

Prepegs make less mess and less waste. 

Prepregs will excrete excess resin during the curing process but those excesses of hand layup, high amount of resin, messy rollers, and drips – are no more a problem. Additionally, if prepregs are handled at room temperature you need not have to take much effort to prevent your resin from setting up before you are ready.

Prepegs need reduced curing time.

After the heat curing cycle is finished, it is ready for service. You do not have to wait for 48 hours to allow a full cure like in a typical hand lamination.

Prepegs are better cosmetics.

As mold preparation and mold release is still needed and will directly affect the cosmetics of the part just like a hand laminate. However, the prepregs eliminate air bubbles and give a smooth, glossy surface.

Disadvantages of Prepregs

  1. Cost. Prepregs are a bit more pricey. Even when you sum up the cost of the resin, cure and fabric, prepegs tend to cost a bit more.
  2. Shelf life. This is a small problem because the prepregs can be stored up to six months at room temperature. However, storage at warm temperatures will reduce the shelf life of the product. Keeping the material cooler will extend life to a significant extent though.
  3. Necessary heat cure. You need to have a heat source and vacuum bagging at a minimum temperature. You must be able to achieve a minimum temperature of 270°F and sustain at that temperature for a minimum of four hours. A number of advanced fabricators use autoclaves but any source of heat can be useful.

Now that you know the advantages and disadvantages of prepegs it’s time to get in touch with us to discuss your requirements. Bhor Chemical is a reputed manufacturer of prepegs in India and is ready to serve your needs!

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