Effects of densification variables on the durability of wood pellets fabricated with Larix kaempferi C. and Liriodendron tulipifera L. sawdust

This study was conducted to examine the effects of species, wood particle size, moisture content of wood particles, pelletizing temperature and time on the durability of larch and tulipwood pellets. The durability of larch pellets was significantly higher than that of tulipwood pellets. The larch pellets fabricated with smaller particles were more durable than those fabricated with large particles. The durability of the larch and tulipwood pellets improved steadily with increasing pelletizing time and temperature. In addition, the durability of both pellets increased with increasing moisture content of the sawdust. Scanning electron microscopy (SEM) showed that the surface of the larch and tulipwood pellets fabricated at a pelletizing temperature of 180 °C for 3 min were similar to that of the commercial wood pellets. SEM-energy dispersive X-ray (EDX) analysis showed that lignin, a potential natural binder between wood particles, was spread throughout both the larch and tulipwood pellets with increasing pelletizing temperature and time. These results suggested that the lignin might contribute to the increase in inter-particles bonding in wood pellets.

► Larch pellets showed higher durability than tulipwood pellets.
► Larch pellets fabricated with smaller particles were more durable.
► The durability improved with increasing pelletizing time and temperature.
► Lignin was spread broadly on wood pellets with increasing pelletizing conditions.