## 3 Results  
### Strain Amplitude Sweep  
The influence of filler loading on storage, G\({}^{\prime}\) and loss, G\({}^{\prime\prime}\) modulus as a function of shear strain for each material is presented in Figure 3.  
Figure 3 shows a well-known fact that by increasing filler concentration the storage, G\({}^{\prime}\) and loss, G\({}^{\prime\prime}\) moduli are increasing [21; 34; 37; 38]. The addition of rigid filler particles increases the overall elasticity of the composite material, hence the storage modulus G\({}^{\prime}\) increases. On the other hand, the loss modulus, G\({}^{\prime\prime}\) is increased due to higher dissipation in the composite material, that occurs because of increased friction between the particles [21]. It can also be seen from the results that with higher filler concentration, the behaviour of the materials changes. Figure 4 presents the values of G\({}^{\prime}\), G\({}^{\prime\prime}\) and phase shift, \(\delta\) as a function of filler content. All parameters were obtained at constant frequency \(\omega\) = 6.28 rad/s and small strains (\(\gamma\) = 0.05%), which correspond to the range of linear viscoelastic response and the conditions, where the particle-particle interactions dominate the material behaviour. Figure 3: The effect of filler concentration on storage, G\({}^{\prime}\) and loss, G\({}^{\prime\prime}\) modulus as a function of shear strain for the fillers: (**a**) Al, (**b**) 316L, (**c**) Ti, and (**d**) GB at 175 \({}^{\circ}\)C.  
The results showed that for each particle loadings, the values of dynamic moduli were similar, or in the same range of magnitude, indicating the viscoelastic behaviour of the composites. The storage and loss modulus increased with increasing filler concentration. Moreover, the transition of the material behaviour from liquid-like (G\({}^{\prime\prime}\) > G\({}^{\prime}\)) to solid-like (G\({}^{\prime\prime}\) < G\({}^{\prime}\)) with increasing filler concentration could be observed for all the composites. The red dotted line in Figure 4 displays the \(\delta\) = 45\({}^{\circ}\) value (G\({}^{\prime}\) = G\({}^{\prime\prime}\)) indicating the liquid to solid transition. At 30 vol.% of filler loading, all materials exhibited values of \(\delta\) > 45\({}^{\circ}\), indicating the viscoelastic liquid-like behaviour. In the case of Al and 316L materials, \(\delta\) values dropped below 45\({}^{\circ}\) at concentrations 45 and 60 vol.%, indicating the viscoelastic solid-like behaviour. Finally, in the case of Ti and GB materials, the transition to solid-like behaviour occurred only at the highest concentrations, i.e., 60 vol.%. It should be emphasised that even at the highest concentrations (i.e., solid-like behaviour), the viscous contribution to viscoelastic behaviour was significant, suggesting the good processability of highly filled composites, studied. Results suggest that since we are comparing the composites with comparable size distributions of filler particles and binder composition, the interactions particle-binder, and particle-particle interactions (surface chemistry) play a crucial role in determining the rheological behaviour of the composites. Strain amplitude tests were primarily performed to determine the range of linear viscoelastic response (LVR). Figure 5 presents the influence of filler material for a particular loading level on the shear strain-dependent storage modulus G\({}^{\prime}\). Figure 4: Storage, G\({}^{\prime}\), loss, G\({}^{\prime\prime}\) modulus, and phase shift, \(\delta\) at constant \(\gamma\) = 0.05%, 175 \({}^{\circ}\)C, and at 6.28 rad/s for the fillers: (**a**) Al, (**b**) 316L, (**c**) Ti, and (**d**) GB. Figure 5: Strain amplitude sweep tests and the effect of filler material on G\({}^{\prime}\) for (**a**) 30 vol.%, (**b**) 45 vol.%, (**c**) 60 vol.% filler loading at 175 \({}^{\circ}\)C and 6.28 rad/s. The results showed that increasing filler concentration increased the consistency of the composites, which could be observed in the increased values of storage and loss modulus (Figure 3).