when the biomass pellets produced, there are specific conditions and adhesive substances. this substances create bonds between particles of biomass materials with each other. What is the conditions and substances you used?
Starch can be used as the binder. the optimum heat applied while pelleting is also an important factor. The heat can be from the friction effect of the pellet mill or applying an external heater. My study revealed that the pellet was formed when the barrel temperatures at about 60-80oC.