N
Y
C
where Y is atom of O, N, S or NH.
Aromatic polyamide fiber, that is polysulfonamide, has the following structure:
The advantage of the developed fibrous PCM over existing laminated plasticss is
the isotropy of their properties, possibility of obtaining the finished product of complex
configuration without additional machining. Fiber waste can be the feedstock for
developed PCM. That expands the development base, contributes to solve the problem
of the use of waste. Compositions from phenol-formaldehyde resin (30-40 mass.%)
and randomly located discrete fibrous organic filler in it with fiber length of 10-20 mm
(60-70 mass.%) were prepared according to the following technological scheme:
- preparation of phenol-formaldehyde solution of the binder: bakelite varnish was
diluted with acetone or alcohol to the concentration of 40-50 % (normalized by dry
oligomer);
- the discrete fibrous filler was impregnated with the binder by mechanical mixing
(chaotic reinforcement scheme);
- at first, phenol-organoprepreg was dried for 24 hours in the air at room
temperature, then in the drying oven at 353 K until the optimal content of the volatile
fraction (6,0-6,5 mass.%) was obtained.
The preparation of organoprepreg in the amount of up to 1 kg was made manually.
For the larger production of organopreg for the making of pilot and industrial
batches of products the technological scheme of the production of PCM was developed.
The technological scheme of the production of PCM of structural design based on the
thermosetting matrixes (Fig. 1) using antifriction or friction additives includes several
stages. At the first stage the binder is obtained by mixing the resin with an irreversible
amount of solvents (acetone or alcohol) (1, 2). Mixing is carried out at the room
temperature for 10-20 minutes. At the second stage discrete fiber filler is uploaded into
the mixer, then
the binder obtained at the first stage, antifriction and friction additives
are added gradually. In such way the fibers are impregnated by the solution of the
binder, and equal distribution of additives occurs (3, 4).
At the third stage the 3-5 cm layer of prepared prepreg is placed in the exhaust
drying oven (5) and dried at the room temperature or at the temperature of 333-353 K
of the content of 3-6 mass.% of volatile fraction depending on the degree of filling of
PCM. At the fourth stage dried prepreg is unloaded and packaged in polyethylene or
paper bags. As necessary, the prepreg weights are weighted for subsequent moulding.
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