Why microcrystalline cellulose is easy to make powder, but nanocellulose is difficult to make powder

The physical properties and structural differences in microcrystalline cellulose (MCC) and nanocellulose (NC) lead to their different ease of preparation into powders.

1. Microcrystalline cellulose (MCC) :

• Microcrystalline cellulose is a polymer composed of the crystalline region portion of cellulose, with a short fiber length and a lower specific surface area. This structure makes microcrystalline cellulose have high stability and can be easily ground into a fine powder.

• Since the particles of microcrystalline cellulose are coarse and do not easily adhere to each other or form agglomerates, powders can be made by conventional drying and crushing methods.

2. Nanocellulose (NC) :

• Nanocellulose consists of smaller fibrous nanostructures, generally between 1-100 nanometers in diameter and can reach a length of several microns. Its specific surface area is very large, resulting in a significant increase in surface energy. This high surface energy makes nanocellulose particles very easy to adhere to each other or form aggregates.

• Nanocellulose has a high moisture retention ability and will form a tight network structure when drying, resulting in their prone to agglomeration into blocks rather than loose powders during drying. In addition, its high surface energy makes the dried powder exhibit strong viscosity and hygroscopicity, making it very difficult to maintain its powdery form.

Therefore, the larger particle size and low surface energy of microcrystalline cellulose make it easier to make powder, while the high surface energy and fine fiber structure of nanocrystalline cellulose make it harder to make powder.