Thepeculiaritiesofformation of cross-linked poly(2-ethyl-2-oxazoline) filmsand nanocompositeson theirbase

Cross-linked polymeric and nanocomposite films based on poly(2-ethyl-2-oxazoline) and modified mineral nanoparticles of hydroxyapatite and silica have been obtained via radical cross- linking initiated by peroxide containing reactive copolymers. The influence of temperature and additional cross-linking agents on the peculiarities of curing process has been studied. The obtained results reveal that at high temperatures the dependence of film gel-fraction values on time has the extremal character. Obtained cross-linked nanocomposite films are characterized by improved physico-mechanical properties that depend on the nature of mineral nanoparticles, content of peroxide containing copolymer and on the presence of additional cross-linking agent.

Time Dependances of the Resistance Coefficients of Polymeric Materials

One of the possible approaches to the analysis of a physical mechanism of time dependence for the resistance coefficients of materials is suggested. The material durability at the constant stress is described using the Zhurkov and Gul' equations and the durability at the alternating stress—using the Bailey criterion. The low strains lead to structuring of a material that is reflected in a reduction of the structure-sensitive coefficient in these equations. This affords 20% increase in the durability. The dependence of the resistance coefficient assumes an extremal character; the maximum is observed at the time to rupture lg tr ≈ 2 (s).

Estimates for two-phase nonlinear conductors via iterated homogenization

Estimates for the overall response of two-phase nonlinear conductors are derived via an iterated homogenization approach. The approach consists in the construction of sequentially laminated microgeometries for which the overall response can be determined exactly. The estimate depends on the one- and two-point microstructural correlations through the volume fractions of each constituent phase and the H-measures of the microstructure. Sample results for power-law random conductors are provided and compared with earlier predictions. The work concludes with a discussion on the possible extremal character of sequential laminates.