when the CNCC dosage increased from 0 to 0.5%, there wasa significant decrease in the air permeability. The air permeabilityreached the minimum of 2.34 mL/s at a CNCC dosage of 0.5%. Whenfurther increasing the CNCC dosage from 0.5 to 0.8%, the air perme-ability had a significant increase up to 2.61 mL/s at 0.7% CNCC andthen reached a plateau. The significant change in air permeabilitycan be mainly ascribed to the distribution state of CNCC. Overall,CNCC can fill in the gap between fibers and/or locate on the surfaceof fibers. At a low dosage of CNCC (0–0.5%), the gap between fiberscan provide enough space for the filling of CNCC, therefore the airpermeability sharply decreased with the increased CNCC dosage.However, excessive CNCC addition (0.7–0.8%) led to the increasedair permeability presumably due to the distribution of part of CNCCon the surface of fibers.