Effect of NaClO dosage on the structure of degummed hemp fibers by 2,2,6, 6-tetramethyl-1-piperidinyloxy-laccase degumming

In this study, different dosages of NaClO were used in the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-laccase degumming system to remove non-cellulosic materials, and their effects on the structure of hemp fibers were analyzed and discussed. A scanning electron microscope was used to depict the surface morphology of fibers after oxidative degumming under various dosages of NaClO in the TEMPO-laccase degumming system. Chemical composition analysis was used to determine the content changes of the different components. Meanwhile, the content of functional groups was also discussed. Fourier transfer infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X-ray diffraction were employed to evaluate the microstructural changes of degummed hemp fibers obtained from the degumming processes with different dosages of NaClO. The results showed that after the TEMPO-laccase system degumming process with a NaClO dosage of 16%, the cleanest and smoothest surface of degummed fibers could be observed and the non-cellulosic materials were significantly removed without any crystalline transformation or damage in the cellulose. This research could shed light on determining favorable operation parameters for hemp oxidation degumming and increasing the degumming efficiency, as well as in the oxidation control and quality assurance of hemp fibers for textile downstream end uses.