## 3 Results and Discussion
### The Results of Rheological Test  
At the stage of loading samples into the working gap of the rheometer, the effect of the GO additive was noticed: for example, the 0% GO/Al\({}_{2}\)O\({}_{3}\) composition, in which graphene oxide was absent, was a brittle and powdery material, while compositions containing graphene oxide quickly became a visually homogeneous mass. For such paste-like samples,  
Figure 1: SEM images of raw Al\({}_{2}\)O\({}_{3}\) powder (**A**,**B**) and dried graphene oxide paste (**C**,**D**). Figure 2: Photographs (**A**) and Raman spectra (**B**) of highly filled Al\({}_{2}\)O\({}_{3}\) + GO polymer compositions. the variability in experimental curves in parallel experiments was less pronounced than for a sample without GO. Figure 3 shows the results of rheological studies. Figure 3A shows the dependences of the dynamic modulus components on the strain amplitude to determine the linear region of viscoelasticity. For all samples, the region in which the modulus of elasticity does not depend on the amplitude of deformation is a narrow band and lies in the range from 0.01 to 0.1%. For further measurements in the oscillation mode, the deformation amplitude was selected equal to 0.02% (indicated by a vertical dotted line in the graph in Figure 3A). It can also be seen in the presented graphs (Figure 3A) that the composition 0% GO/Al\({}_{2}\)O\({}_{3}\), which does not contain graphene oxide, has the highest viscoelastic characteristics. An increase in its content leads to an increase in viscoelastic characteristics, but they do not achieve the characteristics of a sample without graphene oxide, even with its highest content--0.50 vol.%. Figure 3B,C show the dependences of the components of the dynamic module on the deformation frequency at the selected deformation amplitude. For all mixtures, a solid-like behavior is observed when the modulus of elasticity exceeds the loss modulus (G' > G'') over the entire frequency range of deformation and weakly depends on the frequency change. All curves of the loss modulus have a break at a frequency of about 40 s\({}^{-1}\). Figure 3: The amplitude dependence of the dynamic modulus components on deformation for all compositions at 220 \({}^{\circ}\)C (**A**). Dependence of moduli G′ (**B**) and G′′ (**C**) on the frequency at 220 \({}^{\circ}\)C. Dependence of the effective viscosity on shear stress at 220 \({}^{\circ}\)C (**D**). The above curves show a previously identified trend: the addition of graphene oxide to the mixture leads to a decrease in the elastic modulus G\({}^{\prime}\) and loss modulus G\({}^{\prime\prime}\) compared to the 0% GO/Al\({}_{2}\)O\({}_{3}\) composition without graphene oxide. Also, according to the graphs (Figure 3B,C), it can be seen that the addition of graphene oxide has a greater effect on the elastic characteristics of ceramic-filled polymer compositions, since the addition of only 0.10 vol.% graphene oxide leads to a sharp decrease in the elastic modulus G\({}^{\prime}\) of the 0.10% GO/Al\({}_{2}\)O\({}_{3}\) mixture compared to the 0% GO/Al\({}_{2}\)O\({}_{3}\) mixture. However, a further increase in the graphene oxide content from 0.10% to 0.50% leads to an increase in the viscous and viscoelastic properties of the mixtures, but the modulus value for all graphene oxide concentrations remains lower than for the 0% GO/Al\({}_{2}\)O\({}_{3}\) composition. The reduction in moduli G\({}^{\prime}\) and G\({}^{\prime\prime}\) at low concentrations of reduced graphene oxide in ultra-high-molecular-weight polyethylene (UHMWPE) was discussed in a recent study [PERSON], [PERSON] et al. [33]. Similar results were obtained [PERSON] _et al._ [34] by adding 0.10% \(w/w\) graphene nanoplatelets to polyamide-6. As the analysis of the literature shows, the value of the moduli will only increase with an increase in the concentration of graphene and its derivatives in graphene-polymer composites, including composites with polyamide [35], polylactide [36] and polyvinylidene fluoride [37].