20 mm. The results of the research showed that organoplastics with the fiber length of
5 mm (Fig. 4) were characterized by minimal specific heat capacity (C
p
) which
increased from 0,7 to 2,2 kJ/kg K in the temperature range of 298-528 K. Significant
changes in C
p
(more than 50%) of absolute values of heat capacity are observed at
temperatures of 298–473 K; in the area of high temperatures (above 473 K) C
p
of the
examined OP are close in values to all examined lengths of filler fibers.
Heat capacity of OP containg the fiber 10 and 20 mm long was not significantly
different. Characteristic maximum appears on the temperature curves of composites at
348-448 К.
C
p
of organoplastics dropped to 1,98-2,9 kJ/kg∙К at the temperature of
473 К, then it rised again and at 523 К it reached the values close to the C
p
of OP
reinforced with 5 mm long fiber.
Figure 4 The impact of the length of Rusar-C fiber (60 mass.%)
on the specific heat capacity of organoplastics based on PFR:
fiber length 5 (1); 10 (2) and 20 (3) mm
Source: developed by the author
The coefficient of thermal conductivity of the examined OP, which was measured
at the temperature of 295 K, is almost independent of the Rusar-С fiber length. It is
located in the range of 0,153-0,156 (tab. 9). Taking into account that the coefficient of
thermal diffusivity is the inverse value to the specific heat capacity, it is natural that
the maximum value of this thermophysical parameter is characteristic for the OP filled
with 5 mm long OF.
Table 9 The impact of the length of Rusar-C fiber (60 mass.%)
on the coefficient of thermal conductivity and thermal diffusivity
of organoplastics based on PFR
Indicator
Fiber length, mm
5
10
20
The coefficient of thermal conductivity, W/(m K)
0,153
0,155
0,156
The coefficient of thermal diffusivity, m
2
/s
0,12
0,08
0,09
Source: developed by the author
- 434 -