| 摘要 |
In the present invention, there are disclosed cellulose microfibrils, intended particularly for use as stiffening filling agent and a structural component of composite materials, and a process of their preparation. The invented microfibrils are surface treated cellulose microfibrils with L/D ratio grater than 20, preferably greater than 100, and mean diameter 1 to 59 nm, wherein L is the microfibril length and D its mean diameter. At least 25 percent of the hydroxyl group number on the microfibril surface are esterified with at least one organic compound containing at least one function capable to react with the cellulose hydroxyl groups. Provided the organic compound is a compound containing acetyl groups, such as acetic acid, said microfibrils are used as stiffening agent in a material containing acetyl cellulose as polymeric matrix. So filled composite material can be molded to foils, moldings, fibers, or yarns. |
