At the fifth stage the prepreg weights are loaded into preheated to 353 K mold mounted
on the hydraulic press (8). After the closure of the mold and the establishment of the
desired pressure, the temperature is raised at the rate of 2 K/min. The dwell time in the
mold is 1-2,5 minutes per 1 mm of the product thickness depending on the type of
binder and the configuration of detail and its dimensions. When the dwell time finishes,
the heating of the mold
is turned off. Then it is cooled to 353 K by blowing air. After
that the product is pressed out.
Figure 1. Technological scheme production of PCM based on thermosetting
matrixes: 1, 3 - mixer; 2, 4, 7 - scales; 5 - exhaust drying oven for prepreg drying;
6 - prepreg packaging table; 7 - table for hanging the prepreg weights on details;
8 - hydraulic press; 9 - table for machining
Source: developed by the author
At the sixth stage, if necessary, machining of pressed products is carried out.
Thermal studies of the samples were carried out on the derivatograph Q-1500D
of the Paulik-Paulik-Erdey system of the Hungarian MOM company in the temperature
range of 298-870 K with the temperature rise of 10 K/min, mass of the sample was
200 mg. The recording of the curves was carried out with maximum sensitivity.
The testing of standard PCM samples was carried out according to the GOST
(State Standard) for plastics:
- Martens heat resistance – GOST 4650-80 (ISO 75-2: 2013);
- water absorption – GOST 4650-80 (ISO 52: 2002);
- the density of the samples was found by additive and hydrostatic method
according to the GOST 4651-82 (ISO 604: 2002);
- Charpy fracture toughness – GOST 4647-80 (ISO 179-1: 2000);
- ultimate strength under static bending – GOST 4648-71 (ISO 178: 2010);
- breaking point, modulus of elasticity and compressive strain under compression
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