Determination of the optimal content of the polymerization accelerator in epoxy binders for polymer composite materials

The influence of fillers on polymerization parameters of epoxy compositions produced with the use of secondary terpenoid compounds as anhydride type curing agents has not been studied before. The peculiarity of the curing process of thermosetting polymer binders is a sequential transition from one aggregate state to another, i.e. from liquid to gel-like and solid state, and each change of aggregate state is characterized by its phase transition. The knowledge of phase transition temperatures allows to develop optimal curing modes. The knowledge of the phase transition temperature kinetics makes it possible to determine the degree of the binder polymerization. The purpose of this study was to determine the optimal filler content (polymerization catalyst) using differential scanning calorimetry to obtain the final product (plastic sports and running skis) with the required physical and mechanical properties. The modern research method of differential scanning calorimetry allows to fix the heat flux, which characterizes the changes occurring in the substance as a result of heating. This makes it possible to determine the optimal polymerization conditions by changing the filler content in the epoxy binder of the composite material. The results of the research are presented in the form of DSC curves showing all thermal effects manifested in the material in the temperature range under study. The samples of epoxy binders for the composite material were obtained on the basis of epoxy resin (MM = 390‒430), terpenoid anhydride hardener, organic solvents (simple saturated ketones and esters) and modifying additives (plasticizers, polymerization catalysts, fillers). Our research allowed to determine the optimal filler (polymerization catalyst) content (4,5 wt. %) using differential scanning calorimetry to obtain the final product (plastic wrestling skis) with the required physical and mechanical properties (deflection ‒ 27 mm, rigidity of the ski's middle part ‒ 165 N/mm, rigidity index FA (Fisher index ) ‒ 505 N, rigidity of the ski's middle part ‒ 2683 N, rigidity of the ski's toe part ‒ 2,42 N/mm, rigidity of the ski's heel part ‒ 2,31 N/mm).

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