Preparation and properties of microfibrillated cellulose with different carboxyethyl content.

•Carboxyethyl reaction was used as a pretreatment method to prepare MFC.•Samples with different carboxyl content were obtained by controlling chemical dosage.•Carboxyethyl pretreatment could greatly reduces the frequency of grinding.•The diameter of the produced MFC decreased with the increase of carboxyl content.