Cellulose nanofiber (CNF) is an impressive bio resource mainly because of its high mechanical strength, stiffness and optical transparency, which is promising for eco-friendly structural materials. This paper presents the possibility of ecofriendly thin films made with CNF, which has strong, flexible, transparent and lightweight behaviors. The fabrication of thin CNF film and its properties are investigated. Fabrication is carried out by tape casting method to control thickness, followed by separation and drying. Its chemical structure and physical interaction were investigated using Fourier transform infra-red spectroscopy. Mechanical properties are investigated by a tensile test. 3 micron thick CNF film is successfully fabricated. The prepared CNF film is applicable for structural materials in space applications.
Cellulose nanocrystal (CNC) is known to be a good source for structural material due to its impressively high mechanical properties and it is also an excellent dielectric filler due to its electrical polarity originated from its crystal structure. This paper reports a soft electro-active polymer made by blending CNC with poly(urethane), which is named as CPPU. CPPU is an electro-active dielectric elastomer, applicable for smart and active lens. In CPPU, CNC plays the role of filler that improves dielectric constant. For homogeneous distribution of CNC in poly(urethane) matrix, hydrogen boned CNCpoly[di(ethylene glycol) adipate] (PDEGA) was prepared by simple blending as diol of urethane bond. Hexamethylene diisocyanate was used for isocyanate salt as cross-linker. The prepared CPPU exhibits high transparency above 90% and excellent dielectric constant. As a result, the CPPU dielectric elastomer shows large deformation under low electric field. Transparency and large deformation behaviors of CPPU are attractive for smart and active lens applications.
Cellulose is the most naturally occurring biomolecular polymers ensemble into cellulose nanofibers that has both amorphous and crystalline domains in proportions dependent on the source. Cellulose nanofibrils have raised significant interest as excellent structural materials with exceptional mechanical properties. It is important to understand the structure of CNF and its synergy. This study entails molecular dynamics simulations of the cellulose nanofibrils to give insightful understanding of its atomic details in response to temperature. GROningen Machine for Chemical Simulations (GROMACS) is used as the simulations software and All-Atom Optimized Potential for Liquid Simulations (OPLS-AA) force field is chosen for the simulation. To understand the thermally induced structural changes, lattice parameters, crystal density, hydrogen bonding network and other parameters are critically analyzed. The total number of hydrogen bonds is also observed.
This paper reports an eco-friendly nanocomposite made with bamboo cellulose nanofiber and chitin micronanofibers. Bamboo has antibacterial property and is beneficial for human living environment meanwhile chitin is safe for food packaging, highly toxic resistant and able to absorb heavy metals. Chitin was micro-nano fibrillated (CT-MNF) by using aqueous counter collision (ACC) physical method. Cellulose nanofiber (CNF) was isolated from bamboo by treating it with 2,2,6,6-tetramethylpiperidine-1-oxylradical (TEMPO)-oxidation followed by ACC method. Bamboo cellulose nanofiber (BA-CNF) was blended with CT-MNF to form BA-CNF nanocomposite. The morphology of BA-CNF and CT-MNF was determined by an atomic force microscopy and field emission scanning electron microscopy. CT-BA nanocomposites were made with different ratios of BA-CNF and CT-MNF. Properties of CT-BA nanocomposites were investigated by using thermogravimetric analysis, UV-visible spectra, and tensile test. The UV-Vis visible spectrum shows better transmittance of the CT-BA nanocomposite with high BA-CNF content. CT-BA nanocomposite has better surface smoothness. By blending BA-CNF with CT-MNF, CT-BA nanocomposite shows improved mechanical properties.
Miniaturized accelerometer is required in many applications, such as, robotics, haptic devices, gyroscopes, simulators and mobile devices. ZnO is an essential semiconductor material with wide direct band gap, thermal stability and piezoelectricity. Especially, well aligned ZnO nanowire is appropriate for piezoelectric applications since it can produce high electrical signal under mechanical load. To miniaturize accelerometer, an aligned ZnO nanowire is adopted to implement active piezoelectric layer of the accelerometer and copper is chosen for the head mass. To grow ZnO nanowire on the copper head mass, hydrothermal synthesis is conducted and the effect of ZnO nanowire length on the accelerometer performance is investigated. Refresh hydrothermal synthesis can increase the length of ZnO nanowire. The performance of the fabricated ZnO accelerometers is compared with a commercial accelerometer. Sensitivity and linearity of the fabricated accelerometers are investigated.
Cellulose fibers are strong natural fibers and they are renewable, biodegradable and the most abundant biopolymer in the world. So to develop new cellulose fibers based products, the mechanical properties of cellulose nanofibers would be a key. The atomic microscope is used to measure the mechanical properties of cellulose nanofibers based on 3-points bending of cellulose nanofiber. The cellulose nanofibers were generated for an aqueous counter collision system. The cellulose microfibers were nanosized under 200 MPa high pressure. The cellulose nanofiber suspension was diluted with DI water and sprayed on the silicon groove substrate. By performing a nanoscale 3-points bending test using the atomic force microscopy, a known force was applied on the center of the fiber. The elastic modulus of the single nanofiber is obtained by calculating the fiber deflection and several parameters. The elastic modulus values were obtained from different resources of cellulose such as hardwood, softwood and cotton.
In the present investigation, calcinated tea-based cellulose composite films were fabricated via solution casting technique. The fabricated films were characterized by using Fourier transform infrared spectroscopy and differential scanning calorimetry. The effect of calcinated tea loading on the properties of the calcinated tea-based cellulose composite films was studied. The results were showed that the calcinated tea composite films display better mechanical properties and dielectric constant than the pure cellulose films.
Cellulose nanofiber (CNF) isolation from different resources influences the characteristics of the CNF. There are two methods to isolate CNFs, chemical and physical methods. This paper deals with a 2,2,6,6-tetramethylpiperidine- 1-oxylradical (TEMPO-oxidation) chemical method and aqueous counter collision physical method to isolate CNFs. TEMPO-oxidized cellulose nanofiber was isolated using an aqueous counter collision method from two cellulose resource including Softwood bleached kraft pulp (SW) and Hardwood bleached kraft pulp (HW) resources. The CNFs properties were studied by atomic force microscopy, cross-polarize light and UV visible spectrometer. The width of the isolated CNFs is in the range of 15 nm to 20 nm and the length of cellulose nanofibers is around 1000 nm. The HW-CNF offers better transmittance than the SW-CNF. High transmittance of CNF films from both SWCNF and HW-CNF was observed. In addition, the birefringence of CNFs was observed under cross polarized light. The SW-CNF and HW-CNF films showed birefringence phenomenon. More clear iridescence color of HW-CNF sample than that of SW-CNF case.
One of the abundant renewable biomaterials in the world – cellulose is produced from plants forming micro-fibrils which
in turn aggregate of form cellulose fibers. These fibers size can be disintegrated from micro-fibrils to nanofibers by
physical and chemical methods. Cellulose nanofibers (CNF) can be a new building block of renewable smart materials.
The CNF has excellent mechanical strength, dimensional stability, thermal stability and good optical properties on top of
their renewable behavior. This paper reports CNF transparent films made by CNF extracted by the physical method: a
high pressure physical, so called aqueous counter collision method. Natural behaviors, extraction and film formation of
CNF are explained and their characteristics are illustrated, which is suit for IT applications.
In this paper, energy harvesting capability is examined by changing the width of cantilever beam and piezoelectric cellulose. It is started from hypothesis that if cantilever piezoelectric energy harvester with given width are split, it would increase power output due to the fact that the divided pieces have smaller damping ratio than the original single piece, in turn, they are supposed to vibrate with high amplitude at resonance frequency. <p> </p>In the experiment, as a piezoelectric material, cellulose Piezo Paper is prepared with aluminum electrode deposition. By attaching the Piezo Paper on an aluminum beam, a cantilever type piezoelectric energy harvester is made. The given width of the beam is 5cm, and sets of Piezo Papers with different width and number of beams are made as, 5cm x 1, 2.5cm x 2, 1.66cm x 3, 1.25cm x 4, 1cm x 5 and 0.83cm x 6 beams. Cantilever beams are vibrated on a shaker at its resonance frequency and examined their electrical characteristics in terms of output voltage and current. The results are compared with the original beam of 5 cm wide.