Mina Jović1, Radmila Damjanović2, Marija Vuksanović3, Irena Živković1, Vesna Radojević2, Radmila Jančić Heinemann2
1University
of Arts, Faculty of Applied Arts, Belgrade, Kralja Petra 4
2University of Belgrade, Faculty of Technology and Metallurgy, Karnegijeva 4
3Innovation center of Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11070 Belgrade, Serbia
INTRODUCTION
RESULT AND DISCUSSION
Paraloid B-72 is an acrylic copolymer soluble in different solvents and very
resistant to acids, bases, water and oils. It is used in the field of conservation
and restoration for different applications as binder, consolidant, adhesive
and insulator. In 2014 it was recommended by the experts of The
Metropolitan Museum of Art in New York as an adhesive for carrara marble,
in mixture with Paraloid B-48N in volume ratio 3:1. The idea of this experiment
was to increase mechanical hardness of this mixture in order to be used as a
binder for restorations of stone sculptures with larger physical damage.
The hardness of the samples was measured by micro Vickers with load of
100 ponds for 25 s, where for each loading three stitches were produced,
Figure 1. Images obtained by the optical microscope were used to obtain
the hardness using the Image Pro Plus program by measuring the diagonal
for each stitch. The results of micro Vickers hardness of composite
materials with different amounts of alumina doped particles are given in
Figure 2. Micro hardness of the composites increased with the increase of
particles amount.
EXPERIMENTAL PART
The alumina particles doped with iron were synthesized using the sol gel
technique. The starting material was AlCl(OH)5 × 2.5 H2O, demineralized
water and FeCl3· 6H2O. The solution formed the gel that was heat treated at
900°C in order to obtain the suitable crystal structure to be appropriate as
addition to the matrix.
Experiment:
 Phase 1:
• 20.00 g of Paraloid B-72 was dissolved in 27.00 g of acetone and 3.00 g of
ethanol under constant stirring on magnetic stirrer during 40 minutes.
• 20.00 g of Paraloid B-48N was dissolved in 27.00 g of acetone and 3.00 g of
ethanol under constant stirring on magnetic stirrer during 40 minutes.
 Phase 2:
• Alumina particles were doped with iron in acetone in three glasses, in
ultrasonic cleaner, during 30 minutes. 0.60 g of acetone and 5, 10 and 15
wt. % of alumina particles, respectively, were mixed in the glasses.
 Phase 3:
• 0.30 g of dissolved Paraloid B-72 and 0.10 g of dissolved Paraloid B-48N
were added to each of the three glasses containing alumina particles and
samples were poured on glass slides.
• In the fourth glass, 0.30 g of dissolved Paraloid B-72 and 0.10 g of dissolved
Paraloid B-48N were added and sample was poured on glass slide.
• Samples were left to harden under room conditions during 7 days.
Fig. 1. Micrograph of Vickers indentation for composite with 10 wt. %
of alumina particles doped with iron
Table 1. Phases 2 and 3 of the experiment
Fig. 2. Micro hardness vs. amount of alumina particles doped with
iron: a) 7 days after polymerization, b) 14 days after polymerization
Phase 2
Probe
I
II
III
IV
Acetone
0.60 g
0.60 g
0.60 g
Phase 3
Alumina
Dissolved
Dissolved
particles Paraloid B-72 Paraloid B-48N
doped with
iron
0.30 g
0.10 g
0.05 g
0.30 g
0.10 g
0.10 g
0.30 g
0.10 g
0.30 g
0.30 g
0.10 g
CONCLUSION
The micro hardness of the composite materials with alumina
particles doped with iron was investigated in this paper. Alumina
based particles were used as reinforcement in the matrix based
on Paraloid composites. The hardness increased with addition of
the particles in the composition.
ACKNOWLEDGEMENTS
This research has been financed by the Ministry of Education, Science
and Technological Development of the Republic of Serbia as a part of
the projects TR34011.