The SEM micrographs (Fig. 7(a) and (b)) support the fact that the
hot-pressing temperature significantly affects the solidification of the
briquette with 100% of the rice straw (b2 mm). From the SEM
micrographs (40×) of the briquettes with 100% of the smashed rice
straw (b2 mm), the structure of the briquette in test B9 (compressed
at the room temperature) is more porous than that of the briquette in
test B13 (compressed at the temperature of 150 °C). Moreover, as the
hot-pressing temperature increases from the room temperature to
150 °C, the air-dry density of the briquette substantially increases from
0.56 g/cm3 (test B9) to 0.99 g/cm3 (test B13), and the compressive
strength of the briquette significantly increases from 2.2 kgf/cm2 (test
B9) to 65.7 kgf/cm2 (test B13).