Figure 4

Spearman's correlation matrix between weight loss at 300–450 °C (Weight loss %), residual weight at 450 °C (Residual %), volatiles (Vol. %), ash content (Ash %), fixed carbon (FC %), C/N ratio (C/N) and density (Dens. g cm−3). (a) Weight loss of 300–450 °C from G1; (b) 300–450 °C weight loss of G2; (c) Residual weight at 450 °C of G1; (d) Residual weight at 450 °C of G2. Dark blue circles indicate positive correlations while dark red circles indicate negative correlations. The size of the circle indicates the strength of the correlation.