Recently, cellulose fiber reinforced ecofriendly polymer composite for structural material is one of issue due to its sustainability, high mechanical properties, light weight and abundancy. For high strength and sustainable blend, a resin with sustainable, high strength and cellulose compatibility is demanded. PVA-lignin composite is one of good candidate for resin materials due to its high mechanical properties and good adhesion with cellulose. However, low waterproof ability is significant disadvantage of this material. In this paper, esterification reaction with maleic acid was adopted to enhance the mechanical properties. The esterification reaction enhanced waterproof ability and adhesion of PVA-lignin resin to cellulose material.
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.
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.
ZnO nanorods grown cellulose film is a fascinating inorganic-organic hybrid nanocomposite in terms of synergistic
properties with semiconductive functionality of ZnO and renewability and flexibility of cellulose film. This paper reports
the fabrication and evaluation of cellulose ZnO hybrid nanocomposite (CEZOHN). ZnO nanorod is well grown on a
cellulose film by simple chemical reaction with direct seeding and hydrothermal growing. CEZOHN has unique electric,
electro-mechanical and photo-electrical behaviors. The performance of CEZOHN is estimated by measuring induced
photocurrent under UV exposure. Mechanism of UV sensing and its possible applications for flexible and wearable UV
sensor are addressed.
Vertically aligned arrays of ZnO nanowire can be used for many applications such as energy harvesters, UV sensors and mechanical sensors. Here we report the feasibility of a miniaturized accelerometer made with ZnO nanowire. For improving the sensitivity of miniaturized piezoelectric accelerometer, size of piezoelectric ceramic should be large which results in heavy accelerometer and low resonance frequency. To resolve the problem for the miniaturized accelerometer fabrication, ZnO nanowire is chosen. ZnO nanowire, which has piezoelectric property with Wurtzite structure. Since it has high aspect ratio, the use of ZnO nanowire leads to increase deformation and piezoelectric response output. The vertically ZnO nanowire array is grown on a copper substrate by hydrothermal synthesis process. Detail Fabrication process of the miniaturized accelerometer is illustrated. To prove the feasibility of the fabricated accelerometer, dynamic response test is performed in comparison with a commercial accelerometer.
In these days, consumer electronics and medical device for optical diagnosis are minimalized and mobilized. The focusing part is one of crucial parts of optical diagnosis systems to reduce the size and weight. Thus, demand for tunable lens that change the focus itself is increased. To meet the demand, many tunable lens has been studied by utilizing smart materials that responded under mechanical, magnetic, optical, thermal, chemical, electrical or electrochemical stimuli. This paper reports a cellulose nanocrystal (CNC) and poly[di(ethylene glycol) adipate] (PDEGA) blend that is able to respond under electromechanical stimulus. The preparation of CNC/PDEGA and its characterization are illustrated and its actuation behavior is tested . Because the material has high dielectric constant and high reflection index, it is good candidate material for tunable lens.
Electroactive hydrogels are attractive for soft robotics and reconfigurable lens applications. Here we describe the design
and fabrication of cellulose-poly vinyl alcohol based hydrogels. The fabricated hydrogels were confirmed by Fourier
transformer spectroscopy, swelling studies, thermal analysis, surface morphology of fabricated hydrogel was study by
using scanning electron microscopy. The effect of poly vinyl alcohol concentration on the optical and electrical behavior
of hydrogels was studied.
Array haptic actuator to realize texture of button for virtue flight simulator is fabricated by using cellulose acetate (CA)
film. The haptic actuator has independent 3 × 3 cells for identical vibration. Each cell consists of topside CA layer and
bottomside CA layer with two pillars. Two ends of topside CA layer are fixed on the pillars similar with fixed end beam.
By an electrostatic force in the presence of electric field, the topside CA layer vibrates. Each cell shows its resonance
frequency peak in the capable frequency range of vibrotactile feeling from 100 Hz to 500 Hz. The acceleration
performance is shown to be higher than vibrotactile threshold on wide frequency band from 100 Hz to 400 Hz.
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.
Paper based composite with semiconductor nanomaterial is a fascinating orgnic-inorganic hybrid composite that has improved properties of flexibility, biocompatibility and functionality. Cellulose Electro-Active Paper (EAPap) is a kind of paper electric device. To improve functionality of EAPap, ZnO is used as hybrid inorganic composition. Cellulose- ZnO hybrid nanocomposite (CEZOHN) is fabricated by seeding and growing ZnO on cellulose film with a simple chemical reaction. CEZOHN reveals not only electrical, eletromechanical behavior but also photoelectrical behavior. This paper reports specially photo-response and sensitivity of CEZOHN under several light source: UV light, sun and fluorescent light. The fabrication process is briefly introduced, and induced voltage, induced current under light source are investigated. Also, the ZnO effect of CEZOHN and its mechanism is studied and its possibility of application as photosensor, photodiode, photovoltaic device will be discussed.
ZnO is well known semiconductor material with high band gap as well as piezoelectricity. Because of its high performance of electromechanical behavior, ZnO based piezoelectric devices have taken great attention from many research groups. However, ZnO should be grown on a flexible substrate so as to allow its flexibility. Since cellulose is renewable, flexible and biocompatible, ZnO is grown on cellulose by hydrothermal process, then a novel flexible piezoelectric material. We report the fabrication and strain sensor behavior of cellulose ZnO hybrid nanocomposite(CEZOHN) In this research, simple piezoelectric strain sensor based on CEZOHN is made by directly stretching it and by boding it on a cantilever. Its performance is measured in terms of longitudinal and bending strain. This strain sensor shows a good linearity.
Semiconducting ZnO layer chemically grown on regenerated cellulose and its flexible paper transistor were studied. ZnO
layer-cellulose composite was prepared by a simple chemical reaction process which included alkaline hydrolysis at low
temperature lower than 100 °C and used wet regenerated cellulose as a hydrophilic substrate. By increasing the
concentration of ZnO seeding layer on cellulose, the area of ZnO cluster also increases. In the low concentration
conditions from 20 mM to 50 mM, it is observed that the average size of ZnO nanorods increases as the seeding
concentration increases. However, flower-shaped ZnO structure is observed in higher concentration over 50 mM due to
clustering effect during the growth of ZnO rods. Thin ZnO layer composed of nano-rods seemed to be grown well on
regenerated cellulose and layer thickness of ZnO was well controlled by reaction time. Structural data of as grown
ZnO/cellulose provides the crystal orientation-limited growth mechanism of ZnO nano-rod, which can be controlled by
the reaction time of chemical process. Using conventional lift-off process, thin ZnO layer based transistor was fabricated
by forming source/drain as well as gate electrode. More detailed ZnO-cellulose based transistor is discussed.
This paper presents the influence of reaction time for the thickness and particle density of ZnO layer. Paper-like ZnOCellulose
hybrid nanocomposite was fabricated using a low temperature hydrothermal synthesis in the aqueous solution.
This ZnO nanostructure on the cellulose as thin ZnO layer, utilized substrate via simple reaction including the alkaline
hydrolysis, was composed by hydrothermal synthesis. It is revealed that growth mechanism of ZnO nano-rod of the
ZnO-Cellulose hybrid nanocomposite is governed as the crystal orientation limited by structural and morphological
analysis. As the reaction time of chemical process increases, the size of the ZnO nanostructure also increases. These
composite materials can be used to smart materials for flexible electronic or electro-mechanical devices such as
transistors and strain sensors.
We report a flexible paper transistor made with regenerated cellulose and covalently bonded single-walled carbon
nanotubes. Functionalized single-walled carbon nanotubes (SWNTs) are reacted with N, N-Carbonyldiimidazoles to
obtain SWNTs-imidazolides. SWNTs can be covalently bonded to cellulose by acylation of cellulose with SWNTsimidazolides.
Using the product, SWNTs covalently bonded cellulose (S/C) composite paper is fabricated and it is
mechanically stretched to align SWNTs with cellulose chains. Finally, inter-digital comb shaped source and drain
electrode and bottom gate electrode is formed on the paper via lift-off process. Aligned SWNTs can contribute to
establishing stable electron channel paths in the cellulose layer. The alignment of SWNTs can be key a role in improving
characteristics of the paper transistor. The characteristics of the paper transistor are evaluated by measuring mobility, onoff
ratio depending on the alignment of SWNTs in S/C composite paper transistors.