Theoretical and experimental study of the effect of changes in the parameters of the interphase zone of the cured polymeric composite material under the action of microwave radiation on its strength characteristics
Results of calculation of the effective module of shift and the effective volume module of elasticity of the polymeric composite materials (PCM) reinforced by fibers with use of a finite element method are given. It is shown that the value of the specified parameters generally is defined by heterogeneity and relative thickness of an interphase layer (MFS) "fiber matrix". At the same time increase in relative thickness of MFS practically doesn't influence the specified parameters in case of solidity of its structure. Existence of defects in the form of a time leads to decrease in both the shift module, and the volume module. The porosity influences reduction of the specified parameters more than MFS thickness: increase in relative thickness of a layer twice at porosity of 25% leads to decrease in modules of elasticity by (9-10) %, in too time at porosity of 75% similar increase in thickness of MFS decrease in modules of elasticity by 79%. It is established that at the same value of volume of defects (time) reduction of their sizes leads to increase in durability of MFS, expressed in growth of the module of shift by (14,6-23) % depending on thickness at almost invariable size of the volume module. The research by methods of electronic microscopy at increase h5000 microstructures of polymeric composite materials in the field of MFS after their interaction with the microwave oven by the electromagnetic field with a frequency of 2450 MHz within 2 minutes has revealed increase in density of structure of a matrix and interphase layer. The porosity in MFS has decreased by (45-47) % at simultaneous reduction of the sizes of a time by 80-83%, the sizes of agglomerates of a matrix have decreased by 23%, and their quantity has increased for 15%. The specified facts can promote improvement of adhesive interaction of fibers with a matrix. The finite element method has executed the calculations of the module of shift and the volume module taking into account the changes of a microstructure of MFS defined in an experiment which have shown increase in the specified PKM parameters after impact of the microwave oven of the electromagnetic field on (14-20) % that will well be coordinated with the results on increase in durability of PKM received earlier at tests on a bend - (11-16) %, a cut - (13-21) % and interlayered shift - (14-15) %. The revealed change of a microstructure of MFS which is shown in decrease in its porosity and increase in points of contact interaction due to growth of amount of fine agglomerates can be offered as one of mechanisms of increase in durability of the cured polymeric composite materials after influence of the microwave oven of the electromagnetic field.