Mechanical Properties, Morphology and Elemental Composition of Composites Produced from Thermoplastic Polymers Filled with Egg Shell
Authors: Obianuju Ofor Helen 
Published: March 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 mechanical properties of the egg shell-residue polymer composite, to find if there is any new improvement over the properties of the starting thermoplastic polymer and determine the morphology and elemental composition of the composites. 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; Scanning Electron Microscopy (SEM) was used to determine morphology while Energy Dispersive Spectroscopy (EDS) was used to determine the elemental composition of the composites. The results generally showed significant improvements in the mechanical properties of the egg shell filler composites which were largely influence by the amount of filler in the composites. Modulus of elasticity/ tensile strength on almost all the polymer matrix (HDPE, PS, PP and ABS) composites at different percentages values of the properties had better strength. The HDPE loaded with egg shell filler has MoE (Modulus of Elasticity) at 3% of 1115.50 MPa (Mega Pascal) MPa, 6% of 1581.80 MPa, 9% of 662.40 MPa, 12% of 894.34 MPa and 15% of 998.64 MPa, Control (pure HDPE) of 348.38 MPa. For PS the graphs show the result of the 9%, 6%, 12%, 15%, 3% from highest to lowest value to be 1982.60 MPa > 1255.10 MPa >1099.60 MPa > 972.22 MPa > 730.45 MPa and the Control gave 955.59 MPa. The values of PP matrix loaded were 3% (805.71 MPa) > 12% (747.18 MPa) > 9% (571.96 MPa) > 6% (514.18 MPa) > 15% (371.98 MPa), pure PP matrix of 428.20 MPa. ABS/egg shell MoE values were observed as follows: 6% (559.00 MPa) > 3% (384.66 MPa) > 12% (382.84 MPa) > 15% (372.66 MPa) > 9% (327.61 MPa) and control (160.68 MPa). The values of tensile strength for the HDPE egg shell filler composite obtained are 3% (49.02 MPa) > 6% (30.43 MPa) > 12 % (20.56 MPa) >15% (14.81 MPa) > 9% (10.69 MPa) respectively and pure HDPE matrix obtained was 7.40 MPa. For PS egg shell filler composite obtained are 9% (20.56MPa) > 12% (12.34MPa) > 6% = 15% (10.69MPa) > 3% (7.40 MPa) respectively while that of control was (12.34 MPa). PP composites at different percentage loading of egg shell filler show that the values of 3% (12.33 MPa) = 6% (12.33 MPa) > 12% (9.87 MPa) > 9% (5.75 MPa) > 15% (4.93 MPa) and the Control 8.88 MPa respectively. In ABS, the value of 6% (12.34 MPa) > 3% =12% (9.05 MPa) >15% (8,06 MPa) > 9% (7.40 MPa),and 6.58 MPa for pure ABS matrix respectively. The tensile, statistical correlation coefficient using Pearson product-moment between the Control and agro-waste fillers loading on polymer matrices used at different percentages of stress and strain indicate strong positive relationship between the variables. It is evident from the results that HDPE, PS and ABS matrices filled with egg shell composites reinforced at different percentages showed maximum flexural strength than the Control. HDPE at 12% (33.57 N/mm2), 9% (25.43 N/mm2), 6% (18.77 N/mm2), 3% (16.50 N/mm2) and 15% (16.25 N/mm2), while control (14.92 N/mm2). PS polymer composite, only 9% (14.32 N/mm2) value had reduced flexural strength than the Control (17.41 N/mm2); at 6% (34.84 N/mm2), 3% (27.35 N/mm2), 15% (24.24 N/mm2) and 12% (18.65 N/mm2) respectively had higher values than the Control. For PP, 6% (27.35 N/mm2) > 3% (22.37 N/mm2) > 9% (19.90 N/mm2) > 12% (13.72 N/mm2) and > 15% (6.22 N/mm2) respectively had lower values. ABS, 9% (28.60 N/mm2) > 6% (26.67 N/mm2) > 15% (17.50 N/mm2) > 12% (15.65 N/mm2) and > 3% (13.67 N/mm2). Scanning electron microscopy (SEM) was carried out on the samples using imageJ software to estimate the average particle size of the polymer egg shell waste. In some of the composite structures, the particle of the filler material appeared to be homogeneously dispersed in the egg shell-waste/polymer composites; some appeared to be heterogeneously dispersed with voids of white patches while some form an agglomerated mass of different dimensions. The elemental compositional analysis, using Energy Dispersive Spectroscopy (EDS) had all samples contain C and N as a major element present and others as trace; Fe, Al, Mg, P, Zn, Si. This study has provided different combinations of egg shell-waste/egg shell- residue thermoplastic polymer composites which has potential application in the automobile and building construction industry.