Research progress in Ramie fiber extraction: Degumming method, working mechanism, and fiber performance

Ramie fiber, recognized as king of natural fibers, is one of the strongest and longest natural fiber. The fabric made of ramie fibers exhibits the compelling features of being crisp and cool, fast moisture absorption and heat dissipation, as well as favorable air permeability and antibacterial. Since cellulose fibers in raw ramie are stuck tightly by gummy substances consisting of pectin, hemicellulose and lignin, a degumming process is necessary to separate these gummy materials prior to the downstream spinning process. High purified ramie cellulose fibers are supposed to be extracted with high degumming efficiency. However, currently most commonly adopted degumming methods show some inevitable defects, such as long degumming process, high operating cost, serious environmental pollution, and uncontrollable fiber quality. These mentioned issues should be properly addressed in future research work to promote the advancement of ramie fiber industry. The development of green, ecological, environmentally friendly, clean and efficient ramie degumming methods has attracted more and more attention. In this review, the methodologies of degumming processing, including mechanical, chemical, biological and combined degumming methods, are summarized systematically and the resultant properties are also covered. In addition, some research conclusions will be drawn by analyzing the latest process in this field, as well as the views on the remaining challenges and some scientific perspectives or outlook will be finally given for potential readers.