ЕFFECT OF IRON AND NICKEL DITHIOCARBAMATES ON THE PROPERTIES OF MODIFIED POLYURETHANES

Abstract

The effect of modifiers - nickel bis(N,N-dimethyldithiocarbamate) (DTC-Ni) and iron tris(N, N-dimethyldithiocarbamate) (DTC-Fe) depending on their content on the structural peculiarities of polyurethane matrix based on polyoxytetramethylene glycol-1000 4,4’-diphenylmethane diisocyanate and 1,4-butanediol has been studied. The method of IR spectroscopy according to the results of NH groups’, C = O- and COC fragments’ association has shown the structuring effect of modifiers due to the PU matrix coordination. The processes of photolysis occurred as a result of exposure of PU under the conditions of the climate chamber have been also studied by IR spectroscopy method. The influence of modifiers and their content on the modified polyurethanes density has been investigated. The planar structure of DTC-Ni has shown to contribute to the density increase of modified PU as the result of polymer chain coordination, while the spherical structure of DTC-Fe - causes a density decrease due to steric hindrances in the implementation of H-bonds. Modification of polyurethanes with both nickel bis (N, N-dimethyldithiocarbamate) and iron tris (N, N-dimethyldithiocarbamate) as well as UV irradiation and moisture under the conditions of the climatic chamber contribute to the increase of water absorption. Studies of the strength properties of modified polyurethanes in comparison with the matrix under the conditions of the climate chamber have established the photosensitizing effect of nickel and iron dithiocarbamates. By studying the mass of samples of PU-DTС-Fe/Ni after extraction with dimethylformamide in the Soxhlet apparatus it has been found an increase in the level of gel fraction (0.29 - 1.58%) with increasing the modifier content, which confirms the presence of a network structure of modified PU due to radical processes taking place during destruction with the modifier participation. The influence of alkaline and acidic media on the destruction level of both modified polyurethanes and their analogues depending on the modifier content under the influence of climatic chamber conditions has been studied. Comparative derivatographic studies in air of weight loss of modified polyurethanes have confirmed the structuring and thermostabilizing effect of DTC-Ni on the PU matrix due to the probable difficulty of oxygen diffusion to the polymer volume, while the spatial structure of PU-DTC-Fe reduces the thermal stability.