Issue 31

E.M. Nurullaev et alii, Frattura ed Integrità Strutturale, 31 (2015) 120-126; DOI: 10.3221/IGF-ESIS.31.09 124 Fraction number Particle diameter, µm Pore volume ratio Optimum fraction volume ratio Maximum volume filling 1 1 0.465 0.05 0.94 2 15 0.386 0.149 3 600 0.244 0.801 Тable 2 : Parameter values of mixtures of three silica fractions. Fraction number Particle diameter, µm Pore volume ratio Optimum fraction volume ratio Maximum volume filling 1 1 0.465 0.028 0.96 2 15 0.386 0.082 3 240 0.367 0.226 4 600 0.244 0.664 Table 3 : Parameter values of mixtures of four silica fractions. Fraction quantity, piece 2, 3, 4 Experiment temperatures, К 223, 273, 323 Polymer glass transition temperature, К 175 Plasticizer glass transition temperature, К 185 Polymer volume-expansion coefficient 5·10 -4 Plasticizer volume-expansion coefficient 7·10 -4 Volume fraction of the polymer in the binder 0.25 Glass transition temperature of the composite elasomer, К 177 Filler volume ratio in mixed solid rocket propellants 0.75 Chemical bond concentration in the binder, mol / сm 3 1·10 -5 Maximum filler volume ratio 0.84; 0.94; 0.96 Тable 4 : Initial data for calculating the mechanical fracture energy. For comparison, we considered composite materials based on polymeric binders with mixtures of two, three and four (Fig. 2) silica fractions. It is seen that, contrary to Smith failure envelopes [1-4] and [17], the mechanical fracture energy reflects the mechanical resistance of PCM as a filled elastomer more fully in the physical sense, which is important when estimating its operational suitability in particular materials. The dependencies in Fig. 2 allow to evaluate the influence of the quantity of fractions taken in the optimal ratio, on the amount of ruptural deformation (the value of the mechanical fracture energy being practically constant). For example, at the temperature of 223 K b  (%) changes from 0 to 16% (2-fractional silica), from 0 to 25% (3-fractional silica), from 0 to 35% (4-fractional silica), which, respectively, leads to a double increase of b  . A similar phenomenon is observed at temperatures of 273 K and 323 K . The latter circumstance is very favorable for the use of PCM as frost and waterproof asphalt coating of automobile roads. It is important to add that the increase of ruptural deformation of PCM as 3D cross-linked filled plasticized elastomer in accordance with the Eq. (1) is contributed by the decrease in the values of other structural parameters – , , / ch r m     , –