Fig. 3

Changes in composition and surface structure of the residual NMP during degradation. Composition of NMP residues during degradation (a). Degradation rates of NMP components (b). Scanning electron microscopy analysis (c). Time 0 h: SEM micrograph of intact NMP (1500×); the continuous horizontal arrow indicate the intact cellulose fiber, while the discontinuous horizontal arrow indicates the intact hemicellulose. 12 h of microbial degradation (1100×): the short down-arrows indicate the hemicellulose layer removal. 72 h of microbial degradation (1000×): the vertical continuous arrows indicate the exposed cellulose fiber while the vertical discontinuous arrows indicate the grooves formed in the internal matrix. 168 h of microbial degradation (1600×): the short up-arrows indicate the pores and cavities formed in the cellulose fibers. Scale bar = 10 µm