Abstract:
The present study attempted to develop a high-performance oil-resistant rubber material
based on acrylonitrile butadiene rubber (NBR) by incorporating waste eggshell powder
(ESP) as a filler to be utilized in automobiles industry while reducing the commercial
Carbon Black (CB) content. Since CB is obtained from petroleum resources, its
manufacturing process is hazardous and cause environmental pollution. Thus, the use of
calcium carbonate (CaCO3) is found as a remarkable way to replace the CB in the rubber
compounds due to its non-toxic and environmentally friendly nature. Value addition to
waste eggshells was one of the main aspects of this research. The effect of surface
modified CaCO3 filler on the cure, mechanical and swelling properties of NBR
composites with respect to CB was studied. Filler amount was kept constant at 45 phr.
Only the ratio of CB: ESP was changed. Ten ratios of samples were prepared by varying
filler amounts by 5 phr. The surface modification of CaCO3 was confirmed using Fourier
transform infrared spectroscopy. Particle size having 3.05 μm CaCO3 was successfully
obtained from eggshell powder. X-ray diffraction patterns proved that raw eggshell
powder was chemically similar to commercial CaCO3. The vulcanizates were evaluated
by rheological, physical, and mechanical characteristics. The cure times and scorch times
were at an acceptable level. NBR composites with ESP loadings of 0, 5, 10, 15, 20 phr
showed tensile strengths of 7-14 MPa, compression sets of 2.38- 5.49 %, hardness of 61 -
72 IRHD. Therefore, it can be deduced that NBR filled with surface modified eggshell
powder has competed favorably with the standard CB. Replacing CB from ESP loadings
of 5, 10, 15, 20 phr did not show a significant difference in physico-mechanical
properties. Hence eggshell CaCO3 can be considered as one of the best conventional
fillers suited for automotive applications with a high oil-resistant sealing material.
Keywords: Calcium carbonate, Carbon black, Egg shell powder, Filler, Oil resistance
