3.1. Synthesis of MPPM
The influences of single and interactive variables on mechanical
strength of MPPM were investigated and the results of DoEs calculations are presented in Table 3. Main effect plots of single variables and relative influences of all variables are shown in Fig. 2.
Determinative factors for mechanical strength of MPPM were
established as single and two-way interactive variables. Various
single variables (PGA concentration (X2), dozing time (X3), and
mixing time (X4)) noticeably influenced the mechanical strength
of MPPM (Fig. 2a). An increase in mixing time increased the