In this study, Artemisia annua stem waste was identified, for the first time, as a potential natural source to produce cellulose microfibers (CMF), as well as cellulose nanocrystals (CNC) with unique functionalities by using various organic acids. The CMF extraction was carried out using alkali and bleaching treatments, while the CNC were isolated under acid hydrolysis by using sulfuric acid (S-CNC), phosphoric acid (P-CNC), and hydrochloric acid / citric acid mixture (C-CNC). The CMF and CNC physicochemical, structural, morphological, dimensional, and thermal properties were characterized. CMF with a yield of 53%, diameter of 5 to 30 µm and crystallinity of 57% were successfully obtained. In contrast, CNC showed a rod-like shape with an aspect ratio of 53, 95, and 64 and a crystallinity index of 84, 79, and 72% for S-CNC, P-CNC, and C-CNC, respectively. Results suggested that the type of acid significantly influenced the structure, morphology, and thermal stability of CNCs. Based on these results, Artemisia annua stem waste is a great candidate source for cellulose derivatives with excellent characteristics. Graphical Abstract

The relationship between the morphological observations and the physical properties of polyamide 11 (PA11)/clay nanocomposites prepared by melt processing was investigated with a special interest on the use of various contents of silane modified PA11 (PA-m-Si). PA-m-Si was prepared using 1 wt% of 3-aminopropyltriethoxysilane (APTES) added to PA11 in reactive extrusion. The morphological observations by TEM and XRD are presented in conjunction with the rheological and mechanical properties of these nanocomposites. The addition of PA-m-Si generated a net favorable interaction with organoclay that permitted higher level of exfoliation/intercalation resulting from a balance of component interactions. XRD spectra of nanocomposites revealed that the increase of PA-m-Si induced a decrease in peak intensities at high clay loadings (≥5 wt%) which informed about a reduction of stacks intercalated structure leading to a higher degree of delamination and a larger increase of aspect ratio of clay. The rheological properties suggest that the extent of a percolation network can be enhanced by increasing the degree of exfoliation/intercalation at fixed clay content. The tensile and thermal properties were also found to be improved in all cases.

The morphology and properties of polypropylene (PP)/organoclay nanocomposites prepared by melt processing were investigated with a special interest on the different effects of the use of different grafted PP as compatibilizers, i.e., maleic anhydride or silane-grafted species, PP-g-MA or PP-g-Si. When either PP-g-MA or PP-g-Si was added, better improvement of properties was achieved. The addition of PP-g-Si was found to increase the crystallization temperature upon the clay addition in comparison to PP-g-MA. Moreover, the PP-g-MA proved to be more efficient than PP-g-Si. The degree of reinforcement was found to be dependent on the interaction forces between the polymer matrix/clay, which resulted in intercalated/partial exfoliated structures for PP-g-Si while increasing clay content induced a change from exfoliated to intercalated using PP-g-MA, as revealed by transmission electron microscopy observations and X-ray diffraction analysis.

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