Epoxy polymers curing

Fig. 4. Variation of K,c with crosshead speed, y, for a DGEBA epoxy polymer cured with different stated phr of TETA and tested at 20 °C 1,1 Brittle stable (type C) propagation O Kfa,...

The theory has been examined by measuring the ratio K,c/Klcs as a function of j/g, as shown in Fig. 17. The theoretical lines have been fitted to the experimental points by choosing suitable values of the critical distance, c, which is the only fitting parameter. The agreement between theory and experiment has been found to be equally good for many different epoxy polymers cured with many different hardeners, both unmodified 44- 45,51), rubber-modified 45) and containing glass particles 22) and even, under certain circumstances, for structural adhesive joints S3). Values of critical stress, ct,c, and distance, c, for various epoxy materials, obtained from bulk and... 

Kozlov, G. V Bejev,A. A. Zaikov, G. E. The physical reasons for the homogeneous and nonhomogeneous reactions of haloid-containing epoxy polymer curing. J. Appl. Polymer Sci. 2003, 90(5), 1202-1205. 

Bashorov, M. T. Kozlov, G. V Mikitaev, A. K. The nanodimensional effects in epoxy polymers curing process. Chemical Technology, 2010,11 (2), 83-87. 

The effect of addition of SKD-KTRA and SKN-3KTR rubbers on the heat resistance of the UP-652 based epoxy polymer cured by UP-0639 is similar. The addition of SKN-3KTR does not practically change the... 

Let us consider physical significance of particles strange (anomalous) diffusion at epoxy polymers curing [8, 9, 42]. As it is known [42], transport strange processes ate described according to the equation ... 

Proceeding from the considered above importance of steric factor p, the authors of paper [64] performed the study of change character of the indicated parameter value in epoxy polymers curing process on the system EPS-4/DDM example. 

Everything said above related to a full extent to polymers synthesis processes of various types - in these processes by self-organization way fractal objects (macromolecular coils, microgels) are formed, for which temperature, synthesis (curing) duration and so on are external influence. The authors of paper [72] studied the indicated factors influence on epoxy polymers curing process within the frameworks of synergetics. 

Kozlov, G. V. Burya, A. 1. Scaling and fractal analysis of haloid-containing epoxy polymer curing. Composite Materials, 2008,2 (2), 31-35. 

Kozlov, G. V. Bejev, A. A. Shustov, G. B. Lipatov, Yu. S. The features of epoxy polymers curing in fractal space. Theses of Reports of 7-th International Conf. by Chemistry and Physics-Chemistry of Oligomers Oligomers—2000 . Moscow-Perm -Chemogolovka, 4-8 September 2000,207. 

Polymer mechanical properties are one from the most important ones, since even for polymers of different special-purpose function a definite level of these properties always requires [20]. Besides, in Ref [48] it has been shown, that in epoxy polymers curing process formation of chemical network with its nodes different density results to final polymer molecular characteristics change, namely, characteristic ratio C, which is a polymer chain statistical flexibility indicator [23]. If such effect actually exists, then it should be reflected in the value of cross-linked epoxy polymers deformation-strength characteristics. Therefore, the authors of Ref [49] offered limiting properties (properties at fracture) prediction techniques, based on a methods of fractal analysis and cluster model of polymers amorphous state structure in reference to series of sulfur-containing epoxy polymers [50]. 

In Fig. 7.9, the comparison of values 6p calculated according to the Eq. (7.11) and obtained experimentally, is adduced. Now the good coirformity of theory and experiment is observed, both quantitative and qualitative. This confirms postulate that molecular characteristics change in epoxy polymers curing process actually occurs and, if this factor is not taken into account, the Ejprediction can give incorrect results. 

The Fractal Models of Epoxy Polymers Curing Process... 

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