Cellulose carbamate (CCs) was produced from kenaf core pulp (KCP) using microwave reactor-assisted method. The effects of urea concentration and reaction time on the formation of nitrogen content in CCs were investigated. The CCs' solubility in LiOH/urea system was determined and its membranes were characterized. As the urea content and reaction time increased, the nitrogen content form in CCs increased which enhanced the CCs' solubility. The formation of CCs was confirmed by Fourier transform infrared spectroscopy (FT-IR) and nitrogen content analysis. The CCs' morphology was examined using Scanning electron microscopy (SEM). The cellulose II and crystallinity index of the membranes were confirmed by X-ray diffraction (XRD). The pore size of the membrane displayed upward trend with respect to the urea content observed under Field emission scanning electron microscope (FESEM). This investigation provides a simple and efficient procedure of CCs determination which is useful in producing environmental friendly regenerated CCs.
In this study, lignin has been extracted from oil palm empty fruit bunch (EFB) fibers via an organosolv process. The organosolv lignin obtained was defined by the presence of hydroxyl-containing molecules, such as guaiacyl and syringyl, and by the presence of phenolic molecules in lignin. Subsequently, the extracted organosolv lignin and graphene nanoplatelets (GNP) were utilized as filler and reinforcement in photo-curable polyurethane (PU), which is used in stereolithography 3D printing. The compatibility as well as the characteristic and structural changes of the composite were identified through the mechanical properties of the 3D-printed composites. Furthermore, the tensile strength of the composited lignin and graphene shows significant improvement as high as 27%. The hardness of the photo-curable PU composites measured by nanoindentation exhibited an enormous improvement for 0.6% of lignin-graphene at 92.49 MPa with 238% increment when compared with unmodified PU.
A green regenerated superabsorbent hydrogel was fabricated with mixtures of dissolved oil palm empty fruit bunch (EFB) cellulose and sodium carboxymethylcellulose (NaCMC) in NaOH/urea system. The formation of hydrogel was aided with epichlorohydrin (ECH) as a crosslinker. The resultant regenerated hydrogel was able to swell >80,000% depending on the NaCMC concentrations. The hydrogel absorbed water rapidly upon exposure to water up to 48 h and gradually declined after 72 h. The crosslinked of covalent bond of COC between dissolved EFB cellulose (EFBC) with NaCMC was confirmed with Attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy. Crystallinity and thermal stability of the hydrogel samples were depended on the concentrations of NaCMC, crosslinking, and swelling process. The strength and stability of crosslinked network was studied by examining the gel fraction of hydrogel. This study explored the swelling ability and probable influenced factors towards physical and chemical properties of hydrogel.
Bleached kenaf core pulps (BKC) were hydrolyzed in H2SO4 (0.5M) at different time (0min to 90min) at room temperature. After the hydrolysis process, the viscosity average molecular weight (Mŋ) for BKC sample has reduced from 14.5×10(4) to 2.55×10(4). The hydrolyzed BKC was then dissolved in NaOH:urea:water and in LiOH:urea:water mixed solvent at the ratio of 7:12:81 and 4.6:15:80.4, respectively. The increased in hydrolysis time has decreased Mŋ of cellulose leading to easy dissolution process. Higher porosity and transparency with lower crystallinity index (CrI) of regenerated membrane produced can be achieved as the Mŋ reduced. The properties of membrane were observed through FESEM, UV-vis spectrophotometer and XRD. This study has proven that acid hydrolysis has reduced the Mŋ of cellulose, thus, enhanced the properties of regenerated membrane produced with assisted by alkaline/urea system.
The recognition of cellulose nanofibrils (CNF) in the past years as a high prospect material has been prominent, but the impractical cellulose extraction method from biomass remained as a technological barrier for industrial practice. In this study, the telescopic approach on the fractionation of lignin and cellulose was performed by organosolv extraction and catalytic oxidation from oil palm empty fruit bunch fibers. The integration of these techniques managed to synthesize CNF in a short time. Aside from the size, the zeta potential of CNF was measured at -41.9 mV, which allow higher stability of the cellulose in water suspension. The stability of CNF facilitated a better dispersion of Fe(0) nanoparticles with the average diameter size of 52.3-73.24 nm through the formulation of CNF/Fe(0). The total uptake capacity of CNF towards 5-fluorouracil was calculated at 0.123 mg/g. While the synergistic reactions of adsorption-oxidation were significantly improved the removal efficacy three to four times greater even at a high concentration of 5-fluorouracil. Alternatively, the sludge generation after the oxidation reaction was completely managed by the encapsulation of Fe(0) nanoparticles in regenerated cellulose.
The tendency to use cellulose fibrils for direct ink writing (DIW) of three-dimensional (3D) printing has been growing extensively due to their advantageous mechanical properties. However, retaining cellulose in its fibrillated forms after the printing process has always been a challenge. In this study, cellulose macrofibrils (CMFs) from oil palm empty fruit bunch (OPEFB) fibers were partially dissolved for consistent viscosity needed for DIW 3D printing. The printed CMF structure obtained from optimized printing profiles (volumetric flow rate, Qv = 9.58 mm/s; print speed, v = 20 mm/s), exhibited excellent mechanical properties (tensile strength of 66 MPa, Young's modulus of 2.16 GPa, and elongation of 8.76%). The remarkable structural and morphological effects of the intact cellulose fibrils show a homogeneous distribution with synthesized precipitated calcium carbonate (CaCO3) nanoparticles. The shear-aligned CMF/CaCO3 printed composite exhibited a sustained therapeutic drug release profile that can reduce rapid release that has adverse effects on healthy cells. In comparison with the initial burst release of 5-fluorouracil (5-FU) by CaCO3, the controlled release of 5-fluorouracil can be varied (48 to 75%) with the composition of CMF/CaCO3 allowing efficient release over time.
Here, a stable derivative of cellulose, called cellulose carbamate (CC), was produced from Kenaf (Hibiscus cannabinus) core pulp (KCP) and urea with the aid of a hydrothermal method. Further investigation was carried out for the amount of nitrogen yielded in CC as different urea concentrations were applied to react with cellulose. The effect of nitrogen concentration of CC on its solubility in a urea-alkaline system was also studied. Regenerated cellulose products (hydrogels and aerogels) were fabricated through the rapid dissolution of CC in a urea-alkaline system. The morphology of the regenerated cellulose products was viewed under Field emission scanning electron microscope (FESEM). The transformation of allomorphs in regenerated cellulose products was examined by X-ray diffraction (XRD). The transparency of regenerated cellulose products was determined by Ultraviolet-visible (UV-Vis) spectrophotometer. The degree of swelling (DS) of regenerated cellulose products was also evaluated. This investigation provides a simple and efficient procedure of CC determination which is useful in producing regenerated CC products.
The recognition of nanocellulose has been prominent in recent years as prospect materials, yet the ineffectiveness of nanocellulose to disperse in an organic solvent has restricted its utilization, especially as a reinforcement in polymer nanocomposite. In this study, cellulose has been isolated and defibrillated as cellulose nanofibrils (CNF) from oil palm empty fruit bunch (EFB) fibers. Subsequently, to enhance its compatibility with UV-curable polyurethane (PU)-based resin, the surface hydrophilicity of CNF has been tailored with polyethylene glycol (PEG), as well as reduced graphene oxide (rGO). The dispersibility of reinforced modified CNF in UV-curable PU was examined through the transmittance interruption of resin, chemical, and mechanical properties of the composite printed using the stereolithographic technique. Evidently, the enhanced compatibility of modified CNF and UV-curable PU was shown to improve the tensile strength and hardness of the composites by 37% and 129%, respectively.
Drug delivery constitutes the formulations, technologies, and systems for the transport of pharmaceutical compounds to specific areas in the body to exert safe therapeutic effects. The main criteria for selecting the correct medium for drug delivery are the quantity of the drug being carried and the amount of time required to release the drug. Hence, this research aimed to improve the aforementioned criteria by synthesizing a medium based on calcium carbonate-nanocellulose composite and evaluating its efficiency as a medium for drug delivery. Specifically, the efficiency was assessed in terms of the rates of uptake and release of 5-fluorouracil. Through the evaluation of the morphological and chemical properties of the synthesized composite, the established 3D printing profiles of nanocellulose and CaCO3 took place following the layer-by-layer films. The 3D printed double laminated CaCO3-nanocellulose managed to release the 5-fluorouracil as an effective single composition and in a time-controlled manner.
The materials for additive manufacturing (AM) technology have grown substantially over the last few years to fulfill industrial needs. Despite that, the use of bio-based composites for improved mechanical properties and biodegradation is still not fully explored. This limits the universal expansion of AM-fabricated products due to the incompatibility of the products made from petroleum-derived resources. The development of naturally-derived polymers for AM materials is promising with the increasing number of studies in recent years owing to their biodegradation and biocompatibility. Cellulose is the most abundant biopolymer that possesses many favorable properties to be incorporated into AM materials, which have been continuously focused on in recent years. This critical review discusses the development of AM technologies and materials, cellulose-based polymers, cellulose-based three-dimensional (3D) printing filaments, liquid deposition modeling of cellulose, and four-dimensional (4D) printing of cellulose-based materials. Cellulose-based AM material applications and the limitations with future developments are also reviewed.