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

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.

Preparation and properties of bismaleimide resin blended with alkynyl-terminated modifiers

A kind of modified bismaleimide resin, with good processability, heat resistance, and impact strength was developed, using 4,4′-dipropargyloxydiphenyl ether (DPEDPE), N-(4-propargyloxyphenyl)maleimide (4-PPM), and 3-ethynylphenyl maleimide (3-EPM) as modifiers. The DPEDPE, 4-PPM, and 3-EPM were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and 1H-nuclear magnetic resonance (1H NMR), and used to modify the N,N′-(4,4′-diphenylmethane)bismaleimide (BDM)/2,2′-diallyl bisphenol A (DABPA) resin system (BD) to obtain the different blend resin systems of DPEDPE-modified BD (BDD), 4-PPM-modified BD (BDP), and 3-EPM-modified BD (BDE). The curing temperature of BD resin increases with increase of the alkynyl-terminated modifier content. The processability of BD resin was improved with addition of the propargyloxy-terminated compounds. The temperature of 5% weight loss, residual yield at 800°C and glass transition temperature of the cured BD resin increase with increase of the alkynyl-terminated modifier content and can reach 443°C, 46.7% and higher than 380°C. The tensile strength of the cured BD resin decreases with increase of alkynyl-terminated modifier content. The impact strength of the cured BD resin increases with increase of the propargyloxy-terminated compound content and can increase by 65%. The tensile strength, elastic modulus, and impact strength of the cured BD resin blended with DPEDPE can be 73.7 MPa, 4.1 GPa, and 19.6 kJ m−2, respectively. Moreover, the cured BD resin blended with DPEDPE has good water absorption resistance.

Experimental Study of Low Temperature Performance of Porous Asphalt Mixture

Porous asphalt mixture can be used as a road surface paving material with the remarkable advantage to prevent water accumulation and ponding. However, the performance of porous asphalt mixture in low temperature environment has not been thoroughly investigated, and this forms the subject of research in the present study. The mineral aggregate gradation of porous asphalt mixture was designed based on Bailey method, and the low temperature performance of porous asphalt mixture was studied by means of the low temperature bending test. The factors affecting the low temperature performance of porous asphalt mixture were analyzed through the orthogonal experimental design method, and the effects of porosity, modifier content, aging condition, and test temperature on the low temperature performance of porous asphalt mixture were evaluated. The results showed that the modifier content was the most important factor affecting the low temperature performance of porous asphalt mixture, followed by the test temperature, while the porosity and the aging condition were the least. Among the three performance evaluation indicators, namely the flexural tensile strength, maximum bending strain, and bending stiffness modulus, the maximum bending strain had the highest sensitivity to the porosity. It can be seen from the single factor influence test of porosity that there existed an approximately linear relationship between the maximum bending strain and the porosity of porous asphalt mixture, and the maximum bending strain decreased with increasing porosity. Furthermore, in order to ensure the good working performance of porous asphalt mixture in low temperature environment, the porosity should also satisfy the required limits of the maximum bending strain.

Research the Microstructure and Properties of Modified Asphalt from Dry SBS-T

This paper uses a fluorescence microscope to study the microstructure of dry modified asphalt, and compares and analyzes the micro and macro performance of dry and wet modified asphalt. The results show that: in terms of micro performance, when the modifier content is 6%, the dry modifier (SBS-T) becomes to a compact network structure in the asphalt when the shear time is 5 minutes, and it takes 45 min for the modifier to achieve the same result to the wet method. And the macro performance indicators of penetration, softening point, ductility, and viscosity show that the modification effect of asphalt is better by dry modifier is 5 minutes after shearing than the modification effect of asphalt by wet modifier is 45 minutes.

The anomaly in bioactive sol–gel borate glasses

The anomaly in bioactive sol–gel borate glasses: impact of alkaline earth modifier content on both structural and textural properties.

Effect of the coverage level of carboxylic acids as a modifier for barium titanate nanoparticles on the performance of poly(vinylidene fluoride)-based nanocomposites for energy storage applications

Changes in the breakdown strength of nanocomposites show diversity as the modifier content increases for different modifiers.