A WOLLASTONITE SYNTHESIZED IN THE CaCl2–Na2SiO3–H2O SYSTEM AS A MODIFIER OF ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE

Abstract

This paper considers the effect of wollastonite synthesized in the CaCl2–Na2SiO3–H2O model system at a temperature of 20 ºС on the physical and mechanical properties and structure of ultrahigh molecular weight polyethylene. The possibility of optimizing the process of wollastonite synthesis is proposed, which consists in the interaction of the initial components in an aqueous solution at room temperature. The study of the synthesized powders revealed the formation of finely dispersed oval, porous particles. X-ray phase analysis of the synthesis product revealed the presence of an amorphous phase of wollastonite and calcite, which is consistent with its elemental composition. It is shown that the introduction of wollastonite into the polymer matrix leads to a significant increase in the elastic modulus by 58% and compressive strength at a relative deformation of 25% by 27% compared to unfilled ultrahigh molecular weight polyethylene. It was shown that wollastonite structures of the polymer matrix, with the formation of spherulite formations smaller than those of the original polymer. IR spectroscopy revealed the presence of new peaks belonging to the ester group in composites containing wollastonite. The presence of a new oxygen-containing peak is due to the presence of adsorbed water and oxygen molecules in the pores of wollastonite, which leads to the activation of oxidative processes during the processing of composites. It is shown that the occurrence of oxidative processes and the evaporation of adsorbed water leads to weak interfacial interaction (weak adhesion) in the boundary region between the filler and the polymer matrix. However, the occurrence of oxidative processes within the amorphous phase causes an increase in the rigidity of the material. The method of differential scanning calorimetry established a decrease in the values of the enthalpy of melting and the degree of crystallinity with the introduction of wollastonite.