Fig. 4

Lap joint tensile shear strength. Comparison of shear strength (boxplots) of different adhesives (PU = one-component polyurethane, CNFT = PU, mixed with carbon nanofibers/nanotubes, CB = PU, mixed with carbon black), four different postcuring conditions (e.g. 80/1 = 80 °C for 1 h) and arithmethic mean of the wood failure percentage (triangle). ANOVA (p ≤ 0.05) indicates statistical significant differences in tensile shear strength, if letters are different (a ≠ b or a ≠ α). n = number of specimen tested. Boxplots: boxes = quartile of distribution, whiskers = 1.5 of interquartile range, circles = outliers