Temperature impact upon structural and thermal physical properties of epoxy composites modified with 4,4-sulfonil bis (4,1-phenylene) bis (n,n-diethyldithiocarbamate)

Abstract

The effect of the 4.4-sulfonilbis (4,1-phenylene) bis (n,n-diethyldithiocarbamate) (C22H28N2O2S5) modifier on the thermal
properties of the epoxy bisphenol oligomer ED-20 within the temperature range ΔT = 303–873 K has been defined. The heat
resistance by Martens, thermal expansion coefficient, glass transition temperature and shrinkage have been studied. As the result
of the acquired data analysis, the optimum concentration of the C22H28N2O2S5 modifier, significantly improving the thermal
properties of epoxy composite, has been set. It has been demonstrated that in order to get a composite material (CM) or a
protective coating with enhanced thermal properties, it is necessary to introduce the optimum amount of modifier into the epoxy
binder (q = 0.10–0.25 mass parts out of 100 % ED-20 resin). In this case, the composite is formed with the heat resistance value
by Martens of T = 362 K.
On the basis of experimental studies of thermal properties using modern research methods such as differential thermal
analysis (DTA) and thermogravimetric analysis (TGA) the allowable temperature limits at which it is possible to use modified
epoxy composites have been set. СM with the entered modifier of q = 0.75 mass parts and T0 = 601.8 K is characterized by the
biggest destruction temperature value if compared with the matrix (T0 = 600.1 K). The difference between the minimum and the
maximum value is only ΔT0 = 1.7 K, which indicates insignificant positive impact of modifier upon the initial destruction
temperature.
Using DTA curves exothermic effects when exposed to the thermal field within the temperature range of CM ΔT = 591.3–
683.7 K have been defined. It has been found out that the maximum values of exothermic peak, if compared with the matrix
(Tmax = 618.3 K) are Tmax = 626.6–641.0 K, and they are characteristic for СM, filled with the C22H28N2O2S5 modifier in an
amount of q = 0.50–0.75 mass parts. The difference between the minimum (matrix component) and the maximum value is
ΔTmax = 22.7 K, which (within experimental error) shows a significant positive impact of the modifier upon the maximum
exoeffect value. It is said to increase the thermal stability of CM, which in its turn, is due to the stability of physical and chemical
bonds in the material, providing improved physical and mechanical properties of materials under the impact of rising
temperatures.