A simple multibranch strategy was employed to increase the carboxyl contents on the cellulose nanocrystal (CNC) surface. The effects of various sequential grafting of ascorbic acid or citric acid on the morphology, microstructure, thermal stability, dye adsorption capability (methylene blue), and coagulation–flocculation capacity (model kaolin suspension) of the functionalized CNCs were investigated. Cellulose nanocrystals with multicarboxyl groups (CNC-g-AA-g-CA) showed better thermal stability (T max = 359.3 °C), and possessed the highest carboxylic groups of 4.073 mmol/g, which led to a high absolute ζ potential value up to 47.7 mV. Furthermore, the CNC-g-AA-g-CA exhibited excellent coagulation–flocculation capability to kaolin suspension with a turbidity removal rate of 91.07% and good cationic dye (methylene blue) removal rate of 87.8%, indicating that the CNC-g-AA-g-CA can be used as excellent adsorbent and efficient flocculants. In addition, CNC-g-AA-g-CA have good stabilizing effects on soybean oil/water Pickering emulsions, and the resultant Pickering emulsion volume can remain for 30 days or longer.

The image-processing method, based on Photoshop software, was used to analyze the fiber distribution pattern in yarn cross section for vortex-spun yarn. Fiber packing density and fiber effective packing density, as well as the fiber migration index, were investigated to provide a better understanding of the internal structures of vortex-spun yarn. The research results indicate that the vortex-spun yarn has a lower fiber packing density value than the conventional ring-spun yarn at the yarn center and surface. For the bamboo pulp fiber/white cotton blend vortex-spun yarn, the bamboo pulp fibers are more easily distributed in the yarn core. In addition, the coarser the vortex-spun yarn, the higher the migration level of the bamboo pulp fiber tending to migrate towards the inner layer of the blend yarn.

In compact spinning with inspiratory groove, the computational fluid dynamic model, computed with parallel technologies and Fluent 6.3, was developed to simulate the flow field in the compact zone with 3D computational fluid dynamic technology. Flowing state, distributions of static pressure and velocity in the compact zone were characterized and analyzed. The results showed that the compact principle of compact spinning with inspiratory groove consists of compact by airflow and compact by the shape of the inspiratory groove, and the static pressure in the condensing zone is negative, as well as the velocity of airflow in the compact zone is not zero. The fluctuation of the static pressure and velocity near the bottom of the inspiratory groove is relatively bigger and the number of the fluctuation is equal to the number of the round holes in the compact zone.

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Cellulose nanoparticles (CNPs) have been widely reported to improve the crystallization rate, mechanical and thermal properties, as well as degradation behavior of poly­(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Unfortunately, few studies have focused on the relationship between surface functional groups of CNPs and hydrogen bond interactions on the degradation rate and the mechanistic understanding of PHBV nanocomposites. To demonstrate degradation pathways, three types of CNPs with different amounts of surface hydroxyl groups were designed and then incorporated into PHBV to control the thermal stability, mechanical properties, and especially various degradation behavior by modulating the hydrogen-bonding interactions with PHBV, achieving modulated degradation rate of nanocomposites. Furthermore, possible mechanisms describing the thermal, in vitro hydrolytic, and soil degradation of PHBV nanocomposites with various CNPs were proposed. In particular, PHBV nanocomposites reinforced by cellulose nanocrystal citrates with more hydroxyl groups exhibited better properties and degradation behavior than cellulose nanocrystal formates and cellulose nanocrystals. For the possible thermal degradation mechanisms, interfacial hydrogen bond interactions hindered the formation of the six-membered ester ring on PHBV, which improved the thermal stability of the nanocomposites during the degradation process. The rigid hydrogen-bonded networks between the highly crystalline CNPs and PHBV acted as barrier layers, protecting the ester groups on PHBV from being attacked by hydronium ion from the phosphate buffer saline solution. The microorganisms in the soil degrade and digest amorphous domains during the soil degradation process. With modulated degradation rates, high-performance and green nanocomposites could be suitable for biomedical and packaging materials.