Manual Handling

Phenolic prepregs

a. Handling
  • Apart the intrinsic smell of phenolic resins, which is inevitably present in phenolic prepregs, however with much less smell density, the Phepreg® materials do not require any special care and remain in a stable stage, in terms of tack and easy handling, at ambient normal conditions.
  • Usual precautions should be observed. The prepreg contains mainly uncured phenolic resin. The operator has to wear appropriate mask – respirator and work in a clean, dry (R.H. = 50% or less), and ventilated area. The use of clean disposable inert gloves provides protection for the operator and avoids contamination of material and components.

b. Processing
  • Phepreg® prepregs can be cured and processed similar to conventional phenolic prepregs, either in compression (bumping/breathing) molding, vacuum bag, or autoclave.
  • It is also convenient to debulk the prepregs every few layers by subjecting the stack to vacuum in a temporary bag or on a vacuum table. Other know-how techniques can be applied for proper debulking the prepreg layers before curing. Trapped air between layers will prevent proper curing.
  • Whatever the molding process is, the three keys for a successful curing are:
  • o No trapped air between the layers, as well as between the mold and the first layer;

    o Apply a minimum pressure of 1 bar and maintain it along the whole curing time;

    o Apply increasing, or constant, heat in order to bring the inside temperature of the whole compressed prepreg layers, quite equal to the specified curing temperature, usually 115-120C, and maintain it for 20-25 min.

  • If maximum Tg and mechanical performance are required, post cure has to be considered at the specific recommended temperature, generally 150-160C, for 60-120 min.