Degradable materials are provided that may be utilized in various wellbore treatment fluids, such as hydraulic fracturing fluids. In particular, the degradable materials can be formed from cellulose esters that are capable of effectively degrading at specific rates when exposed to the aqueous environments commonly found in wellbores. More particularly, the degradable materials can be in the form of degradable fibers that are formed from the cellulose esters described herein.

Provided is a method that enables industrially efficient production of an esterified polysaccharide product. A method for producing an esterified polysaccharide product, the method including reacting a polysaccharide-containing biomass, a basic ionic liquid with a pKa of a conjugate acid of an anion from 2 to 19 as a calculated value in a vacuum, and an esterifying agent using a kneader equipped with a shear force application mechanism. A cation constituting the basic ionic liquid is preferably one selected from the group consisting of an imidazolium cation, a pyridinium cation, and a tetraalkylammonium cation.

The invention relates to cellulose esters, the ester groups of which are at least partially containing phosphorus and are based on unsaturated carboxylic acids and reactive phosphorus components, wherein the latter are preferably phosphorus derivatives of sugar alcohols or of tartaric acid derivatives. The invention also relates to methods for preparing novel phosphorus-containing cellulose esters and to their use as flame retardants for plastics.