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Monday, March 15, 2010

Storage and Handling of Prepregs

Prepregs should be stored as received in a cool dry place or in a refrigerator. After removal from refrigerator storage, prepreg should be allowed to reach room temperature before opening the polyethylene bag, thus preventing condensation (a full reel in its packaging can take up to 48 hours). Typically prepregs have a guaranteed shelf life at - 18 ºC of 12 months. Tack life at 23 ºC depends on the matrix, and is clearly defined on the relevant Product Data Sheet.
Prepregs are particularly low-risk in terms of handling hazards for the following reasons :

• Prepreg is covered on both sides by protective coverings, which are not removed until assembly lay-up. It should be cut to shape before removing the protective coverings and virtually no handling of the prepreg is necessary.

• Unlike wet lay-up methods of fibre reinforced composite manufacture, where dry fibre and liquid resin are used,uncured prepregs have no loose fibrous dust and are splash-free, leak-free and spillage free.

• Prepregs are volatile-free at normal room temperature.

• Prepregs have a moderate/low tack level at normal room temperature.

However, the usual precautions when handling synthetic resins should be observed, ie. always wear gloves and ensure arms are covered, thus avoiding skin contact with the product. Repeated unprotected touching of prepreg can cause an allergic reaction.
Dust from machining cured product will contain fibrous material, inhalation of which should be avoided. Provide positive dust extraction and collection from the cutting zone. Protect against fire and explosion by avoiding dust formation and ignition sources when machining cured product. Dust from products containing carbon fibre is electrically conductive.

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