Physico-Mechanical Properties of Composites Produced from Thermoplastic Polymers Filled with Egg Shell
Authors: Ofor Helen Obianuju 
Published: April 2021

The aim of this research is to develop environmentally friendly, lightweight composites using egg shell, as filler in some thermoplastic polymer matrices Polypropylene (PP), High Density Polyethylene (HDPE), Acrylonitrile-Butadiene-Styrene (ABS) and Polystyrene (PS) polymer; to determine the physico-mechanical properties of the egg shell agro-residue polymer composite, to find if there is any new improvement over the properties of the starting thermoplastic polymer composites.This research work studied the reinforcement potential of egg shell in thermoplastic polymers (HDPE, PS, PP and ABS). Egg shell was collected from the surroundings of Ekwulumili in Nnewi-South L.G.A of Anambra State, Eastern Nigeria where they have been dumped after usage. The research was carried-out at JUNENG NIG LIMITED Enugu, Civil Engineering Department Laboratory University of Nigeria and Chemical Engineering Department Laboratory Ahmadu Bello University (ABU), Nigeria; between May 2016 and August 2018. The agro-wastes were grand into power and incorporated into the virgin thermoplastic polymers as filler at varied levels of 3%, 6%, 9%, 12% and 15%. The virgin thermoplastic polymers were used as the Control in the study. The mechanical properties of the composites produced were determined using American standard for Testing and Materials (ASTM), Standard Testing Methods. The results generally showed significant improvements in the physico-mechanical properties of the egg shell filler composites which were largely influence by the amount of filler in the composites. However, the water absorption capacities of the composites were found to be higher than those of the virgin thermoplastic polymers; an indication that egg shell reinforced at different percentage values are not compactable with polymer matrices due to the hydrophilic nature of natural fibers. HDPE at 15% (8.95%), 3% (4.28%), 9% (3.11%), 12% (0.88%) and 6% (0.85%) and Control (0.00%). PS, at 3% (8.24%), 6% (7.49%), 12% (2.18%), 9% (1.13%), 15% (0.49%) and Control (0.12%). PP, 9% (5.02%), 12% (3.99%), 3% (3.06%), 6% (0.78%) and 15% (0.67%) and Control (0.13%). ABS at 6% (5.52%), 12% (5.03%), 15% (1.50%), 3% (1.02%) and 9% (0.83%) respectively also had very high-water absorption than the Control (0.11%).
Brinell hardness property of egg shell/polymer matrix composites had better values than the virgin polymer; HDPE value at 6% (39.48 N/mm2) > 3% (39.46 N/mm2) > 9% = 12% (39.40 N/mm2) > 15% (39.39 N/mm2) and Control (36.44 N/mm2). PS at 3% (39.60 N/mm2) > 6% (39.56 N/mm2) > 9% (39.54 N/mm2) > 12% (39.12 N/mm2) > 15% (38.85 N/mm2) respectively had higher brinell hardness above the Control (37.04 N/mm2). PP had value only at 3% (29.28 N/mm2) that showed lower brinell hardness; 6% (39.35 N/mm2) > 15% (37.55 N/mm2) > 9% (37.36 N/mm2) and > 12% (36.93 N/mm2) respectively showed higher brinell hardness than the Control (36.32N/mm2). ABS; 12% (39.54 N/mm2) > 6% (39.40 Nmm2) > 3% equal to 9% (39.39 N/mm2) and > 15% (39.35 N/mm2) respectively had better brinell hardness than the pure polymer. Abrasion results of all egg shell/polymer matrix composites used (exception of PS) showed poor abrasion values than the Control; For HDPE the value at 3% (29.47 g/s), 9% (25.03 g/s), 12% (23.54 g/s), 15% (23.13 g/s) and 6% (22.36 g/s) and Control (14.57 g/s). PS, at 12% (12.16 g/s), 3% (10.79 g/s), 6% (8.35 g/s),15% (6.69 g/s) and 9% (5.59 g/s) and Control (16.20 g/s). PP had at 12% (55.47 g/s), 6% (47.90 g/s), 3% (40.16 g/s), 9% (32.80 g/s) and 15% (22.11 g/s) and Control (18.02 g/s). ABS at 3% (15.05 g/s), 15% (87.52 g/s), 6% (24.10 g/s), 12% (22.08 g/s), 9% (21.07 g/s) and Control (17.39 g/s).
The impact strengths absorbed higher amount of energy than the Control in PP, HDPE, ABS, 3%, 6%, 9% of PS, 3%, and 6% of PP in egg shell composites. HDPE at 12% (3.12 J/mm2) > 3% (2.95 J/mm2) > 6% (2.88 J/mm2) > 9% (2.35 J/mm2) > 15% (1.63 J/mm2) and Control (1.84 J/mm2). In PS, 3% (4.03 J/mm2) > 6% (2.86 J/mm2) > 9% (2.67 J/mm2) >12% (1.48 J/mm2) > 15% (1.25 J/mm2) and Control (1.98 J/mm2). PP at 6% (2.16 J/mm2) and 3% (1.63 J/mm2) showed higher impact strength while 15% (1.23 J/mm2) > 9% (1.08 J/mm2) > 12% (0.91 J/mm2) respectively showed lower impact strength than the Control. In ABS 15% (1.14 J/mm2) absorb lower energy while 9% (1.17 J/mm2) had equal value with control (1.17 J/mm2); at 12% (3.18 J/mm2), 6% (2.16 J/mm2), and 3% (1.38 J/mm2) respectively absorb higher energy than the Control. This study has provided different combinations of agro-waste/agro-residue thermoplastic polymer composites which has potential application in the automobile and building construction industry.