This study presents the piezoelectric property test of ultrathin cellulose nanofiber (CNF) film and calculate the piezoelectric coefficient by using piezoresponse force microscopy (PFM). Cellulose is known to have piezoelectric properties. However, its measurement is not easy. The mechanism of PFM is based on detecting the piezoresponse induced by the inverse piezoelectric effect from target sample. We applied the PFM to characterize the piezoelectric properties of ultrathin CNF film which is fabricated by microfabrication method under clean room condition. For characterizing the piezoelectric properties of ultrathin CNF film, the PFM standard sample periodically poled lithium niobite (PPLN) sample was utilized as reference sample. By applying AC voltages through conductive AFM probe to ultrathin CNF film surface, the amplitude data of ultrathin CNF film is recorded and used to calculate the piezoelectric coefficient. Corona poling, electrical in-plane alignment and high magnetic field alignment methods are introduced to align the ultrathin CNF film. According to the different alignment methods, the aligned ultrathin CNF films show different piezoelectric behavior.
A continuous fabrication process for high-strength nanocellulose based long-fiber (NLF) has been researched as a key process to fabricate natural fiber-reinforced polymer composites with high specific modulus and strength. The process was custom-designed by utilizing the wet spinning and stretching methods with dry process. First, nanocellulose was isolated from wood pulp by using a combination of chemical and physical methods. Apparatus for the process was self-produced and the process parameters such as the speed, position, number of wheels were experimentally investigated. Among the various designs, two specific setups were chosen and the speed of the wheels was optimized. The success of the process was determined by the sustainability of the setups for more than 30 min. The results were evaluated by using the tensile test and scanning electron microscope.
Being a naturally occurring biopolymer, cellulose is popular and deeply explored for its amazing mechanical properties. Cellulose nanofibers are modelled and molecular dynamics simulations conducted using GROMACS and All-Optimized Potential for Liquid Simulations (OPLS-AA) force field is used for parameterization. The mechanical properties and structural stability of the cellulose nanofibers are investigated via the simulations. We explore the hydrogen bonding disparities on the CNF structure as it is subjected to different pull forces. The results show that the hydrogen bonds decrease every time a pull force is increased, with the decrement more significant when large pull forces are applied than low pull forces.
Nanocellulose has a great potential as a renewable material due to its high mechanical strength, high Young’s modulus, low density and eco-friendliness. Once a bulk material is made with it, then the bulk material made with nanocellulose can be a renewable bulk material, which is eco-friendly, lightweight and strong. Furthermore, it is known fact that cellulose has piezoelectricity due to its ordered domain of cellulose including crystal domains of cellulose. Thus, by aligning cellulose domains in the renewable bulk material made by nanocellulose, an eco-friendly and smart material can be developed. This paper aims at testing the feasibility of bulk material processing by using nanocellulose, specifically cellulose nanocrystal (CNC). The fabrication was carried out through steam with high temperature and high pressure to form hydrogen bonds between CNCs, followed by a heat and pressure molding. Its crystalline structure and physical interactions are investigated by using X-ray diffraction. Morphology and mechanical properties are investigated by scanning electron microscope and dynamic mechanical analysis.
Nanocellulose-based long fiber (NLF) is a key element of natural fiber-reinforced polymer composites which have ultimate impact for the future technology, owing to its merits in terms of high specific modulus, high strength, environmentally-friendliness and low cost. In this study, NLF is made by aligning cellulose nanofibers (CNFs), which are isolated from wood pulp by a chemical and physical methods. A high degree of alignment of the CNFs leads to increased number of hydrogen bonds among CNFs with enhanced mechanical properties of NLF. In this study, wet spinning, mechanical stretching, electric field and magnetic fields are used simultaneously or continuously to align CNFs effectively. To fabricate strong NLF, the process parameters are experimentally investigated, and their effects are evaluated by using the tensile test, scanning electron microscope.
Cellulose nanofiber (CNF) is known to have high mechanical strength, high Young’s modulus, optical transparency, low thermal expansion coefficient and low density, which are beneficial for flexible display substrates and optical films. The purposes of this study is to fabricate ultrathin CNF film and to explore its physical properties. CNF suspension is extracted by 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) oxidation combined with aqueous counter collision (ACC) treatment from bleached hardwood pulp. The CNF suspension is cast on a thin positive photoresist (PR) layer by a doctor blade casting method followed by removing PR layer and drying on a polytetrafluoroethylene (PTFE) sheet to obtain ultrathin CNF film. Morphology of ultrathin CNF film is characterized by atomic force microscopy and the thickness of the film was characterized by FE-SEM. Transparency and birefringence of the prepared ultrathin CNF film are tested by using an UV-visible spectrometer and a digital camera. The piezoelectric response microscopy (PFM) is utilized to analysis the piezoelectric properties of ultrathin CNF film.
Atomic force microscopy (AFM) is known for measuring the mechanical properties of nanomaterials. It has been used for measuring the mechanical properties of few kinds of fibers, such as carbon nanotubes, gold nanofibers, graphene. In this study, the effect of various sources on the elastic modulus of cellulose nanofibers (CNFs) was investigated by using AFM three-points bending test. The CNFs were extracted from hardwood, softwood, bamboo and cotton by using aqueous counter collision (ACC) system and the morphology of CNFs were studied by AFM. CNFs were successfully transferred to the AFM calibration chip and the three-points bending test was performed. CNFs were considered to be circular shape by taking into account the AFM tip radius and the Young’s modulus was calculated. The calculation results indicate that the range of Young’s modulus is between 102 and 131 GPa varying upon the cellulose resources.
The fabrication of cellulose long-fiber (CL) is necessary for eco-friendly and high strength composites development. CL can be made with cellulose nanofiber (CNF) that has high mechanical strength and modulus. However, the mechanical properties of CL in early studies were shown to be lower than those of original CNF. An idea of fabricating strong CL is to align CNFs so as to make strong hydrogen bond between CNFs. To achieve this, alignment of CNF is very important. In this study, high dc magnetic field is introduced to align the CNFs. The CNFs are aligned perpendicular to the direction of dc magnetic field due to its negative diamagnetic anisotropy. CNFs isolated by TEMPO oxidation and aqueous counter collision method are used in this experiment. The CNF emulsion is located in the high dc magnetic field and cured. Alignment of CNF is investigated by using optical microscopy, scanning electron microscopy and mechanical tensile test.
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.
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.
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.
The objectives of this study are to prepare and investigate the optical and tensile properties of the obtained cellulose nanopaper structures. A ball mill mechanical pretreatment combined with a wet pulverization process by using an aqueous counter collision machine were used to extract CNFs from softwood and hardwood bleached kraft pulps. Cellulose nanofiber (CNF) nanopapers were fabricated via vacuum filtration and oven drying method. The mechanical and optical properties of the fabricated nanopaper were investigated by using tensile test and UV-vis spectrometer. Results have shown that the softwood sample demonstrated better mechanical properties than the hardwood sample. UV-vis transmittance measurements did not indicate significant differences.
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.
Cellulose is one of abundant renewable biomaterials in the world. Over 1.5 trillion tons of cellulose is produced per year in nature by biosynthesis, forming microfibrils which in turn aggregate to form cellulose fibers. Using new effective methods these microfibrils can be disintegrated from the fibers to nanosized materials, so called cellulose nanocrystal (CNC) and cellulose nanofiber (CNF). The CNC and CNF have extremely good strength properties, dimensional stability, thermal stability and good optical properties on top of their renewable behavior, which can be a building block of new materials. This paper represents recent advancement of cellulose nanocrystals and cellulose nanofibers, followed by their possibility for smart materials. Natural behaviors, extraction, modification of cellulose nanocrystals and fibers are explained and their synthesis with nanomaterials is introduced, which is necessary to meet the technological requirements for smart materials. Also, its challenges are addressed.
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.
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.
In this present study experimental and finite element analysis of cellulose based electro-active paper energy harvester is presented. Electro-active paper coated with metal electrode is a smart form of cellulose and exhibit piezoelectric effect. Specimens were prepared by depositing electrodes on both sides of the cellulose film. A 50 mm x 50 mm cellulose film coated with aluminum electrodes was bonded on 100 mm x 50 mm x 1 mm aluminum host structure. The voltage output to input acceleration frequency response across a load resistor of 1 MΩ is recorded by conventional energy harvesting experimental setup at the fundamental vibration mode of the EAPap cantilever beam. A coupled piezoelectric-circuit finite element model is developed in which load resistor is directly connected to energy scavenging device. Voltage output FRF is measured for the cases, without proof mass, and by adding a 2 grams proof mass near the tip of the cantilever. The experimental voltage FRF value is 7.6 V/g at 75.1 Hz and is improved to 13.8 V/g at 62.2 Hz when a stainless steel proof mass of 2 grams is added. The presented CPC-FEM model results agree reasonably well with the experimental results. Despite the fact that the electro-mechanical coupling coefficient of electro-active paper is lower than other available piezoelectric materials, it is biocompatible, cheap and naturally occurring polymeric material. It is also very flexible and posses similar piezoelectric characteristics such a PVDF which inspire to use EAPap in energy harvesting applications.
In the recent times, cellulose-based Electro-Active Paper (EAPap) has been investigated to have electro-mechanical coupling and piezoelectric effects which are promising characteristics for a smart material. In this paper, the effects of electrodes of EAPap are investigated for vibration energy harvesting. Although piezopolymers have smaller value of electro-mechanical coupling constants as compared to the piezoceramics, but are very flexible, which motivates to use these materials as potential media for flexible energy harvesting. Cellulose based Electro-active papers are deposited with different metal electrodes like aluminum, gold and silver. The fabricated samples are tested with aluminum cantilever beam under an input excitation. The effects of area of electrodes are also investigated by comparing the output voltage at the different area of electrodes ranging from 400mm2 to 1200mm2. EAPap cantilever are tested at lowest resonant frequency and under varying acceleration amplitude to maximize the output voltage. From the experimental results, it is concluded that the potential of EAPap as a flexible energy harvester are very promising.
Cellulose films coated with ZnO nanoparticles constitute an important material for practical applications ranging from the film paint industry to the technologically appealing area of optoelectronic paper. ZnO-cellulose hybrid nanocomposite was fabricated by growing ZnO on regenerated cellulose directly. This organic-inorganic nanocomposite exhibits excellent piezoelectric behavior. This paper reports electrical and electromechanical behaviors of the ZnOcellulose hybrid nanocomposite. The fabrication process is briefly introduced, and induced voltage, remnant polarization as well as piezoelectricity between cellulose substrate and ZnO-layers are investigated. Also its charging and discharging behaviors are studied, and its application possibility for super capacitor, paper battery, field effect transistor will be discussed.
This paper investigates a direct inkjet printing method for electrode patterning on cellulose Electro-Active Paper
(EAPap). Flexibility and transparency of the EAPap are advantageous for a versatile substrate in flexible printable
electronics. The effects of curing conditions are evaluated by electrical resistivity and morphological analysis. To
fabricate EAPap device, inter-digital transducer (IDT) electrodes are printed on the EAPap with drop-on-demand inkjet
printing method. Silver patterns are obtained from organometallic silver ink by jetting and heat treatment at 160°C in air.
IDT patterns are made on cellulose for variety and extensive application of inkjet printing electronics.