UV resistance of bast fibers

Ramie, flax, hemp, kenaf and Apocynum venetum (A. venetum) are all natural bast fibers which are composed of different content of cellulose, hemicellulose, lignin and other gum. The inherent functionality of these bast fibers is worth studying. In this study, cotton and polyester (PET) fibers were chosen as the control, UV protection and antiphotoaging ability of these bast fibers were all tested and analyzed. Results showed that hemp, kenaf and A. venetum composite films (CFs), which had high ability of UV absorbance, possessed higher Ultraviolet Protection Factor value of 180.48, 85.35 and 82.97 respectively, much higher than that of ramie, flax CFs and the control samples. PET fibers revealed the strongest antiphotoaging ability of all with a 76% retention of initial strength after photoaging for 48 h. The semi-degummed fibers, such as flax, kenaf and hemp fibers had more gum residues and stronger UV absorption of extracted solution, and could reserve 67, 69 and 56% of their initial strength after accelerated photoaging for 48 h, respectively. These semi-degummed bast fibers showed better antiphotoaging ability than that of the completed degummed fibers such as ramie and A. venetum.