Adsorption Performance of Human-like Collagen by Alkali-modified Kapok Fiber: A Kinetic, Equilibrium, and Mechanistic Investigation

Collagen-based dressings achieve excellent repair of the skin during metical cosmetology, which has received a lot of attention recently. Although great progress has been made on using biomass fiber as dressing carrier, more research is required on developing novel biomass fibers because of the limitations of (i.e., high cost and complex processing) of existing materials. In this study, the adsorption behaviors of two human-like collagen were studied by examining the Kapok fiber that was modified using alkali consisting of various amounts of the mass fraction. Results show that the alkali-modified Kapok fiber surface becomes rough with vertically arranged grooves, and the cross-section depicts the hollow cavity structure. The composition analysis of alkali modified Kapok shows that alkali dissolves part of the hemicellulose and lignin. Additionally, the surface energy rises sharply and the water contact angle changed from hydrophobic to hydrophilic. The adsorption amount of raw Kapok fiber is around 0.6g/g, which accounts for only one twenty-first of the adsorption amount of alkali-treated Kapok (around 12.6g/g), while the equilibrium adsorption amount was not sensitive to alkali concentration. The kinetics of human-like collagen followed both Quasi first and Quasi second order kinetic model, implying that the adsorption process where characterized by both physisorption and chemisorption. Finally, characterization of the AKF-2 coupled with the studies based on the inter-particle diffusion model showed a three-step of human-like collagen diffusion consisting of surface diffusion, inter-fiber diffusion and fiber' hollow cavity diffusion. Our results demonstrate a perfect high absorption performance of Kapok fiber providing a potential for application of collagen-base dressings.

Thermal-Induced Dielectric Response In Mechanically Durable Polyvinylidene Fluoride/Tubular Kapok Fiber Encapsulated Polyethylene Glycol Composite Films

Dielectric materials with thermally responsive property are being pursued in fields such as next-generation sensors, smart switches, and novel actuators. These applications require that the dielectric materials have mechanical durability and stable serviceability besides thermally responsive dielectric behavior. Herein, we report a novel thermally responsive, mechanically durable, and low-cost dielectric composite simply fabricated by vacuum impregnating polyethylene glycol (PEG) into Kapok fiber (KF) and compounding them with polyvinylidene fluoride (PVDF). A remarkable dielectric susceptibility, controlled dielectric transition temperature and obvious thermal hysteresis of the composite films induced by the solid-liquid phase transition of PEG are demonstrated. The effect of molecular weights of PEG on the dielectric response behaviors is evaluated. Such thermally responsive dielectric materials with satisfactory mechanical durability will offer a chance toward constructing thermally responsive systems for safe and stable operation.

The wettability and micro-equilibrium of different essence liquids to alkali-treated kapok fiber

Kapok fiber is a natural hollow fiber that has superior biocompatibility and biodegradability and is naturally antibacterial. Because of its unique properties, it has great potential in the application of postoperative repair dressings. The wettability and micro-equilibrium of kapok fibers play a critical role in dressing applications. In this study, the critical adhesion volume and adhesion energy of essence liquid to alkali-treated kapok fiber (AKF) were quantitatively calculated to explore the wettability and micro-equilibrium through the equilibrium wetting theory. Meanwhile, the three-phase contact line (TCL) structure was described. The results showed that the critical adhesion volumes of the three types of essence liquid for AKF were 3.45, 3.81, and 4.12 μL, respectively. Moreover, the critical volumes and low error rates derived from the equilibrium wetting theory were 3.41 μL and 1.16%, 3.99 μL and 4.51%, and 4.60 μL and 10.43%, respectively. Therefore, the critical volume of adhesion could be well calculated by the theoretical model. The average adhesive energies of essence liquid to the AKF were 0.38, 0.45, and 0.56 J, respectively, caused by the difference in liquids properties. The TCL showed a mechanical lock and bonding points at both ends because of the curvature difference and higher surface energy. These results are proposed to inspire the design of a liquid carrier of kapok fibers based on the fiber network structure.

Characterization of Cellulose Acetate Based Scaffolds Derived from Kapok Fiber (Ceiba pentandra (L) Gaertn)

Utilization of natural biopolymers has shown potential in generating innovations for tissue engineering applications. This study aims to fabricate scaffolds from cellulose acetate derived from kapok fiber. Cellulose is extracted from raw kapok fibers by alkali treatment and delignification then synthesized into cellulose acetate. Kapok cellulose acetate (KCA) is dissolved in dimethyl sulfoxide to fabricate the scaffold. Materials were characterized using Attenuated Total Reflectance – Fourier Transform Infrared (ATR-FTIR) spectrometer, X-ray diffractometer (XRD) and Differential Scanning Calorimeter (DSC). FTIR analysis has shown that cellulose was extracted from kapok and cellulose acetate was successfully synthesized. XRD analysis also confirmed the presence of cellulose acetate. Results have also shown that synthesized KCA seems to have higher crystallinity than commercially available cellulose acetate (CCA). The degree of substitution (DS) of KCA was found to be 2.85 which is close to the DS value of tri-substituted cellulose acetate. DSC analysis has shown lower glass transition temperature of 52.15°C but higher degradation temperature of 300.43°C than the CCA. Moreover, the values for the enthalpy of fusion for two endotherms of KCA (44.0556 J/g and 18.6946 J/g) are higher than the values for CCA by 344% and 261%, respectively; thus, indicating the higher degree of crystallinity for synthesized KCA samples.

Kapok Fiber- Structure, Characteristics and Applications: A Review

Kapok fiber is a light, cottony, pale yellow to brown fiber obtained from Kapok fruit. The fiber is characterized by a large, hollow lumen and is generally hydrophobic due to its waxy surface. The fiber is difficult to spun into thread and it is commonly used as filling in mattresses, pillows, stuffed toys and upholstery. Compared to other natural fiber, kapok’s use is limited in application. However, it is now gaining attention in the scientific community as an important material due to its outstanding properties. This review will provide a detailed overview on the structure, composition and morphology of kapok fiber. It will also discuss the recent researches conducted on kapok fiber including its application as adsorbent material, biocomposite, biotemplate, electrode material and others.