• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.1
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• pp.51-57
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• 2023

Because of the global pollution caused by plastic disposal, demand for eco-friendly transformation in the packaging industry is increased. As part of that, the utilization of polylactic acid (PLA) as a food packaging material is increased. However, it is necessary to improve the crystallinity of PLA by adding nucleating agents or to improve the modulus by adding fillers because of the excessive brittleness of the PLA matrix. Thus, the cellulose nanofiber (CNF) was fabricated and dried to obtain a powder form and applied to the CNF/PLA nanocomposite. The effect of CNF on the morphological, thermal, rheological, and dynamic mechanical properties of the composite was analyzed. We can confirm the impregnated CNF particle in the PLA matrix through the field emission scanning electron microscope (FE-SEM). Differential scanning calorimetry (DSC) analysis showed that the crystallinity of not annealed CNF/PLA nanocomposite was increased approximately 2 and 4 times in the 1st and 2nd cycle, respectively, with the shift to lower temperature of cold crystallization temperature (T_cc) in the 2nd cycle. Moreover, the crystallinity of annealed CNF/PLA nanocomposite increased by 13.4%, and shifted T_cc was confirmed.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.518-527
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• 2015

In this study, nanocomposite mats consisting of cellulose nanocrystals (CNCs) and poly(lactic acide) (PLA) were electrospun from a suspension mixture consisting of tetrahydrofuran at room temperature. Morphology study showed that fibers of electrospun composite mats were aligned in three dimensional surface along the fiber long-axis. Average diameter of the electrospun fibers decreased with an increase in the CNC loading level. Tensile strength of the electrospun fibers mat decreased with an increase in the CNC loading level because of bead formation in the formed fibers and low interfacial bond strength between PLA and CNC. Meanwhile, thermal stability of the electrospun nanocomposite mats was effectively improved as the amount of CNC increased.

• Composites Research
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• v.33 no.4
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• pp.213-219
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• 2020

Recently, global facing environmental issues have been raised caused by plastic waste. Hence, increasing the demand for interest in environmentally friendly materials. In this row, research on engineering composite materials also replacing the synthetic reinforcement by introducing natural fibers. However, focus on the strength and interfacial adhesion between matrix and reinforcement is very essential in natural fiber composite, which is insufficient in the literature. There are number of approaches for improving the mechanical strength of the composites, one of the common methods is to reinforce additive nanoparticles. The present investigation, bio-additives were synthesized utilizing bio-waste, cheap, bio-degradable sea-weed powder that could replace expensive nanomaterials and reinforced into the CFRP composite through Hand lay-up followed by a vacuum process. Mechanical properties were evaluated and analyzed through microanalysis. The results concluded that synthesized additives are effective for improving mechanical properties such as tensile, flexural, impact, and shear strength. Overall, the results confirmed that the fabricated composites have potential applications in the field of engineering applications.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.1
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• pp.35-41
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• 2013

In this study, we investigated the effect of the number of passes through agrinder on the pore characteristics of nanofibrillated cellulose (NFC) mat. The beaten pulp suspension was used to make NFC suspension using a grinder. To evaluate the pore characteristics of a NFC mat, the surface morphology of the dried NFC mat was observed with FE-SEM and the specific surface area was analyzed with BET nitrogen gas adsorption. The structure of NFC mat was changed with the different number of passes and drying methods. The specific surface area of NFC mat increased with the increase in the number of passes. The 20-passed NFC mat had 20 times larger specific surface area ($141m^2/g$) compared to the 0-passed NFC mat. The specific surface area was strongly correlated with the average pore size in NFC mat. The average pore diameter in NFC mat was calculated from the gas sorption isotherms using BJH model. The value was 13 - 15 nm, indicating that the NFC mat had mesoporous structure.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.2
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• pp.42-52
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• 2015

In this study, cellulose nanofibrils (CNF) were modified through carboxymethylation or TEMPO-mediated oxidation and their effects on ionicity and characteristics of sheet, film, and foam were investigated. Carboxymethylation was carried out on pulp fibers as a pre-treatment before preparation of CNF. The gel-like and translucent CNF hydrogel was obtained by grinding of carboxymethylated cellulose fibers. Carboxymethylated CNF film and freeze dried sheet showed higher transparency than that of untreated CNF. The CNF sheet with high strength and the CNF foam without large ice crystals were obtained by using the carboxymethylated CNF. TEMPO-mediated oxidation was carried out as a post-treatment of CNF. The zeta potential and charge demand of TEMPO-oxidized CNF were increased with an increase in oxidation time and addition amount of NaClO. The density of sheet made of TEMPO oxidized CNF was increased with the amount of oxidizing agent. The TEMPO oxidized cellulose nanofiber (TOCN) which was obtained from supernatant after centrifugation could be converted to transparent film.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.78-86
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• 2014

Since cellulose nanofibrils (CNF) has large specific surface area and high water holding capacity, it is very difficult task to remove water from the CNF suspension. However, dewatering of CNF suspension is a prerequisite of following processes such as mat forming and drying for the application of CNF. In this study, we evaluated the drainage of cellulose fibers suspension under vacuum and pressure conditions depending on the number of grinding passes. Also, the effect of the addition of cationic polyelectrolyte on dewatering ability of CNF suspension was investigated. Regardless of dewatering condition, the total drained water amount as well as the drainage rate were decreased with an increase in the number of grinding passes. Pressure dewatering equipment enables us to prepare wet CNF mat with relatively higher grammage. The cationic polyelectrolytes improved the dewatering ability of CNF suspension by controlling the zeta potential of CNF. The fast drainage was obtained when CNF suspension had around neutral zeta potential.

• Journal of Radiation Industry
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• v.4 no.4
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• pp.353-357
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• 2010

Silver nanoparticles (AgNPs) can be used in the areas such as integrate circuit, cell electrode and antimicrobial deodorant. In this study, AgNPs have been prepared by using $AgNO_3$ aqueous solution in the carboxymethyl cellulose (CMC) hydrogel. CMC powders were dissolved in deionized water, and then irradiated by a gamma-ray with a radiation dose of 50 kGy to make CMC hydrogel. CMC hydrogels were dipped into $1.0{\times}10^{-2}M$ $AgNO_3$ solution for 1 hour. After that, the swollen hydrogels were irradiated by gamma-ray for the formation of AgNPs. The characteristics of silver nanoparticles in the CMC hydrogels were monitored by UV-Vis and the morphological study and dispersed coefficient of particles were investigated by FE-SEM/EDX. It was observed that the sodium salt in the CMC is crucial to the formation of silver nanoparticle. Finally, antibacterial tests indiacted that the hydrogel containing silver nanoparticle has antibacterial activity.

• Textile Coloration and Finishing
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• v.33 no.1
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• pp.40-47
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• 2021

As modern society develops, it becomes very complex and diverse, and interests in the convenience of life and the natural environment are gradually increasing. Products used in our daily life are also changing according to the needs of consumers, and food packaging is one of them. In particular, retort packaging materials have been used for the purpose of long-term preservation of contents, but the appearance of products suitable for recent environmental issues has been somewhat delayed. Therefore, in order to develop eco-friendly and human-friendly products by replacing the metals used in the existing retort packaging materials, the possibility of substitution was examined using cellulose nanofibers, a natural material. As a result, it can be seen that all functions can be replaced according to the existing long-term storage characteristics for retort packaging films. In particular, not only oxygen permeability and water vapor permeability, which are one of the most important factors, but also heat resistance, which is heating durability, is evaluated as applicable to commercialization compared to products using metals currently in use.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.284-288
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• 2022

Polypropylene (PP) powder/cellulose nanofibers (CNF) 1 wt% slurry composites were prepared by filtering their suspension under reduced pressure and dried them in an oven followed by the use of a twin screw extruder. PP modified with side branches and polar groups was used. The side branches and polar groups were introduced into PP by using divinylbenzene and maleic anhydride (MAH), respectively. As a result of examining the dispersibility of CNF and the physical properties of the composite, it was confirmed that the composite prepared from PP powder/CNF 1 wt% slurry showed equal or higher levels in tensile and flexural strength as compared with those using the composite prepared from CNF powder.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.114-119
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• 2016

In this study, we tried to add the conductivity to natural polymer like bacterial cellulose (BC) coated with the conductive polymer PEDOT:PEG, graphene and silver nano-wire (AgNW). Sulfuric acid of 10 to 20% was previously mixed with PEDOT:PEG and then the solution was electron spin-coated on the BC membrane. And then, additive coating with graphene and AgNW were done to improve conductivity, which was examined by hall effect. As the result, we confirmed a considerable improvement of conductivity compared to BC-coated film without sulfuric acid treatment as $2.487{\times}10^{10}$ vs $8.093{\times}10^{15}$ ($1/cm^3$), showing higher electron density with $3.25{\times}10^5$ times. Also, we identified that changed particle type to the polymer type by sulfuric acid using SEM analysis. For FT-IR analysis, it was confirmed that S-O radical ($1200cm^{-1}$) increased in the sulfuric acid treatment than non-treated sulfuric acid. As the method used very small amount of PEDOT:PEG, its transparency could be kept, and pre-treatment process of sulfuric acid will be able to simplify the production process.