## 3 Results
### ATR-FTIR Analysis
The 316L filler material mostly consisted of Fe alloys where vibration peaks of metallic materials usually appear in the 800 to 200 cm\({}^{-1}\) range. By measuring ATR spectra of the 316L filler alone (magenta curve), we identified a vibration peak at 779 cm\({}^{-1}\) related to Fe-vibrations. ATR spectra of 316L composite materials (316L_30, 316L_45, and 316L_60) showed the characteristic peaks for PP and Fe characteristic vibration. Vibration peaks characteristic for the \(-\)CH\({}_{2}\), \(-\)CH\({}_{3}\) groups of the aliphatic chain of the PP were observed. In the range identified as characteristic for Fe-vibrations, a shift from 779 cm\({}^{-1}\) to the lower wavelengths of 729 cm\({}^{-1}\) for all three composite materials was observed. Similarly, as in the case of Al material, the characteristic peak of cyclic MAPP at 1778 cm\({}^{-1}\) disappeared (again indicating the opening of the anhydride ring), and the peak at 1736 cm\({}^{-1}\) associated with the vibration of C = O-O- symmetric stretching of MAPP implied the bonding of Fe- group to the binder system (to the MAPP). Figure 10: ATR-FTIR spectra of Al materials, reference binder system and Al filler material. The spectra of Ti composite materials at all three concentrations, as well the binder system and just the Ti filler reference sample are shown in Figure 12. Typical vibrations of PP, MAAP, and thermal stabiliser, with the same characteristic peaks as described before were detected in Ti composite materials. The spectrum of Ti filler reference material showed characteristic peaks in the wavelength range from 800 to 600 cm\({}^{-1}\), and typical peaks for metal oxides was detected at 858 and 775 cm\({}^{-1}\) (the vibration of Ti-O bond). The ATR spectra of Ti composite materials showed the characteristic peaks for PP (as in the previous two materials). Additionally, here, with the addition of filler particles, the characteristic peak of MAPP at 1778 cm\({}^{-1}\) disappeared indicating the opening of the MA anhydride ring. As opposed to the previous two materials, it seems that no vibration peak shifts could be detected. Chemical bonding of Ti filler material to the binder system could not be confirmed in this case. This might be due to  
Figure 11: ATR-FTIR spectra of 316L materials, reference binder system and 316L filler material. Figure 12: ATR-FTIR spectra of Ti materials, reference binder system, and Ti filler material. the limitations of this particular technique. Although, the peak at 1736 cm\({}^{-1}\) indicates a physical interaction between Ti-O groups and carbonyl groups of an opened ring of MAPP. The final spectra in Figure 13 show spectra of GB composite materials at all three concentrations, a spectrum of the binder system and as a reference also the spectrum of GB filler. The spectrum of filler material (GB) showed peak vibrations at around 1040 cm\({}^{-1}\), typical for Si-O vibrations of glass (silicate) materials. In the composite materials, we detected the presence of silicates, since vibration peaks occurred at 1040 cm\({}^{-1}\). In this case, it was clear that there was no peak shift related to GB filler (at 1040 cm\({}^{-1}\)) and that there was no chemical bonding between the filler material and polymeric binder system. However, as in all investigated materials, also, in this case, the peak at 1778 cm\({}^{-1}\) disappeared as the filler was added indicating the ring opening behaviour of MAPP. At the same time, the existing peak at 1735 cm\({}^{-1}\) indicated a physical interaction between Si-O groups and of carbonyl groups of an opened ring of MAPP.