Investigation on flexural strength of cellulose-microfibril-reinforced polymer composites

The aim of this research work was to find the flexural stress and the flexural modulus of cellulose-microfibril-(CMF)-reinforced epoxy polymer composites. CMFs were extracted from banana fibers using acid–alkali treatment. The influences of three parameters – namely, sodium hydroxide (NaOH) concentration (% (w/w)), fiber diameter (μm) and fiber volume (% (w/w)) – on the flexural behavior of composites were investigated. The response surface methodology (RSM) was used for deciding the composition of specimens. A three-factor, three-level Box–Behnken Design (BBD) model of RSM was selected for investigating the effect of input variables on flexural behaviors and for obtaining the optimization conditions. By solving the regression equations and analyzing the three-dimensional response surface plots obtained from BBD, optimized desirability ramp values were obtained. The optimized flexural stress and flexural modulus values were 88.83 and 9571.5 MPa, respectively, obtained by using optimized input values of sodium hydroxide concentration (% (w/w)), fiber diameter (μm) and fiber volume (% (w/w)) of 19.32, 250 and 3.73, respectively.