C. I. Nwoye^1,, M. C. Obelle², S. O. Nwakpa¹, C. W. Onyia³, I. Obuekwe⁴, N. E. Idenyi⁵

This paper presents the predictability of the impact strength of calcium carbonate (CaCO₃) reinforced epoxy resin composite based on CaCO₃ Input Concentration (CIC) and impact load referred to as Sustained Stress At Impact (SSAI) which is the impact load. Results from experiment, derived and regression model prediction show that the impact strength of CaCO₃-epoxy resin composite increase with decrease in CIC and increase in SSAI. A two-factorial model was derived, validated and used for the predictive analysis. The derived model showed that the impact strength of CaCO₃-epoxy resin composite is a linear function of CIC and SSAI. The validity of the derived model expressed as: ξ = 0.2223 ₰ - 0.0532 ϑ + 9.3519 was rooted on the model core expression ξ – 9.3519 = 0.2223₰ - 0.0532 ϑ where both sides of the expression are correspondingly approximately equal. Results from evaluations indicated that the standard error incurred in predicting CaCO₃-epoxy resin composite impact strength for each value of the CIC & SSAI considered, as obtained from experiment, derived model and regression model were 0.3807, 0.3698 and 2.9277 x 10^-5 & 0.8081, 0.3909 and 0.7808 % respectively. The composite impact strength per unit CIC as obtained from experimental, derived model and regression model predicted results are 0.1175, 0.1088 and 0.1063 J/m %^-1, respectively and the correlations with CIC & SSAI were all > 0.9. Maximum deviation of model-predicted CaCO₃-epoxy resin composite impact strength from the experimental results is 7.45%. These invariably translated into over 92% operational confidence for the derived model as well as over 0.92 reliability response coefficients of CaCO3-epoxy resin composite impact strength to CIC and SSAI.

prediction, impact strength, CaCO₃-epoxy resin composite, CaCO₃ input concentration, sustained stress at impact