Colorless and transparent polyimide nanocomposites using organically modified montmorillonite and mica.

In this study, we introduce a method for replacing the glass used in existing display electronic materials, lighting, and solar cells by synthesizing a colorless and transparent polyimide (CPI) film with excellent mechanical properties and thermal stability using a combination of new monomers. Poly(amic acid) (PAA) was synthesized using dianhydride 4,4'-biphthalic anhydride (BPA) and diamine 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (AHP). Various contents of organically modified montmorillonite (MMT) and mica were dispersed in PAA solution through solution intercalation, and then CPI hybrid films were prepared through multi-step thermal imidization.

Effect of organoclay on the physical properties of colorless and transparent copoly(amide imide) nanocomposites.

Copoly(amic acid) was prepared using the diamine monomer ,'-[2,2'-bis(trifluoromethyl)-4,4'-biphenylene]bis(4-aminobenzamide) (TFAB) and the anhydride monomers 4,4'-(hexafluoro-isopropylidene)diphthalic anhydride (6FDA) and 4,4'-biphthalic anhydride (BPA). Thereafter, a colorless and transparent copoly(amide imide) (Co-CPAI) film was synthesized through various heat treatments. Co-CPAI hybrid films with a TFAB : 6FDA : BPA molar ratio of 1 : 0.

Monomer Dependence of Colorless and Transparent Polyimide Films: Thermomechanical Properties, Optical Transparency, and Solubility.

Six poly(amic acid)s (PAAs) were synthesized by reacting bis(3-aminophenyl) sulfone with various dianhydride monomers such as pyromellitic dianhydride, 4,4'-biphthalic anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 4,4'-oxidiphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride. These PAAs were then converted to polyimide (PI) films by thermal imidization at various temperatures. To obtain colorless and transparent PI (CPI), the dianhydride monomer used in this study had an overall bent structure, a structure containing a strong electron-withdrawing -CF substituent or an alicyclic ring.

Beef Toughness and the Amount of Greenhouse Gas Emissions as a Function of Localized Electrical Stimulation.

This study investigated the effect of localized electrical stimulation on Hanwoo beef quality. It focused on the chemical and physical properties of the Longissimus thoracis (LT) and Biceps femoris (BF) muscles, and it explored the implications of carbon dioxide (CO) reduction achieved by accelerating tenderization via localized electrical stimulation. The results show that the application of localized electrical stimulation (45 V) had no significant impact on the TBARS (thiobarbituric acid reactive substances) of either the LT muscle or the BF muscle.

Effects of various types of organo-mica on the physical properties of polyimide nanocomposites.

Poly(amic acid) (PAA) was synthesized using dianhydride 4,4'-oxydiphthalic anhydride and diamine 3,3'-dihydroxybenzidine, and polyimide (PI) hybrid films were synthesized by dispersing organo-mica in PAA through a solution intercalation method. Hexadimethrine-mica (HM-Mica), 1,2-dimethylhexadecylimidazolium-mica (MI-Mica), and didodecyldiphenylammonium-mica (DP-Mica), which were obtained via the organic modification of pristine mica, were used as the organo-micas for the PI hybrid films. The organo-mica content was varied from 0.

Waste-Wood-Isolated Cellulose-Based Activated Carbon Paper Electrodes with Graphene Nanoplatelets for Flexible Supercapacitors.

Waste wood, which has a large amount of cellulose fibers, should be transformed into useful materials for addressing environmental and resource problems. Thus, this study analyzed the application of waste wood as supercapacitor electrode material. First, cellulose fibers were extracted from waste wood and mixed with different contents of graphene nanoplatelets (GnPs) in water.

Colorless and transparent poly(amide imide) nanocomposites containing organically modified hectorite.

Polyamic acid (PAA) was synthesized using the diamine monomer ,'-[2,2'-bis(trifluoromethyl)-4,4'-biphenylene]bis(4-aminobenzamide) and dianhydride monomer 4,4'-oxydiphthalic anhydride. Colorless and transparent poly(amide imide) (CPAI) hybrid films were prepared multi-step thermal imidization of PAA in which various contents of nano-filler were dispersed. The CPAI hybrid films were prepared by dispersing organoclay STN, which was obtained by organically modifying hectorite, in CPAI by solution intercalation with various contents ranging from 1 to 7 wt%.

Effects of organoclay on colorless and transparent polyimide nanocomposites: thermomechanical properties, morphology, and optical transparency.

Although aromatic polyimide (PI) exhibits excellent mechanical performance and thermal stability, its dark color limits applicability in optical displays. Therefore, it is desirable to manufacture colorless, transparent PI (CPI) nanocomposite films that retain excellent physical properties. In this study, a solution intercalation method was used to disperse organoclay (Cloisite 25A; CS25A) in poly(amic acid), which was prepared using 4,4'-oxydiphthalic dianhydride and 3,4'-oxydianiline as monomers.

Mechanical Properties and Electromagnetic Interference Shielding of Carbon Composites with Polycarbonate and Acrylonitrile Butadiene Styrene Resins.

As environmental pollution becomes a serious concern, considerable effort has been undertaken to develop power devices with minimal production of carbon dioxide (CO) and exhaust gases. Owing to this effort, interest in technologies related to hybrid and electric products that use fuel cells has been increasing. The risk of human injuries owing to electromagnetic waves generated by electrical and electronic devices has been also rising, prompting the development of mitigating technologies.

Photocatalytic VOCs Degradation Efficiency of Polypropylene Membranes by Incorporation of TiO Nanoparticles.

A class of serious environmental contaminants related to air, namely volatile organic compounds (VOCs), has currently attracted global attention. The present study aims to remove harmful VOCs using as-prepared polypropylene membrane + TiO nanoparticles (PPM + TiO NPs) via the photocatalytic gas bag A method under UV light irradiation. Here, formaldehyde was used as the target VOC.

Electromagnetic-Interference-Shielding Effectiveness of Lyocell-Based Carbon Fabrics Carbonized at Various Temperatures.

Lyocell is a biodegradable filament yarn obtained by directly dissolving cellulose in a mixture of -methylmorpholine--oxide and a non-toxic solvent. Therefore, herein, lyocell fabrics were employed as eco-friendly carbon-precursor substitutes for use as electromagnetic interference (EMI) shielding materials. First, a lyocell fabric treated with polyacrylamide via electron beam irradiation reported in a previous study to increase carbon yields and tensile strengths was carbonized by heating to 900, 1100, and 1300 °C.

Annealing effect of thermotropic liquid crystalline copolyester fibers on thermo-mechanical properties and morphology.

A series of thermotropic liquid crystal copolyesters (Co-TLCPs) was prepared by melt polymerization using 2,5-diethoxyterephthalic acid (DTA), 2,7-dihydroxynaphthalene (DHN), and p-hydroxybenzoic acid (HBA) monomers, where the HBA content was varied (0-5 mol). At 3 mol HBA, the Co-TLCPs formed nematic mesophases, while below this concentration, the liquid crystalline phase did not appear. The Co-TLCP sample with 3 mol HBA was subjected to melt spinning and heat-treated under various conditions (temperature and time) to investigate their effect on the thermo-mechanical properties and degree of crystallinity.

Comparison of Properties of Colorless and Transparent Polyimide Nanocomposites Containing Chemically Modified Nanofillers: Functionalized-Graphene and Organoclay.

Poly(amic acid) (PAA) was synthesized from dianhydride 4,4-(4,4-isopropylidenediphenoxy)bis(phthalic anhydride) and diamine bis [4-(3-aminophenoxy) phenyl] sulfone. Colorless and transparent polyimide (CPI) hybrid films were synthesized through thermal imidization after dispersing nanofillers using an intercalation method in a PAA solution. C16-GS and C16-MMT, in which hexadecylamine (C16) was substituted on graphene sheet (GS) and montmorillonite (MMT), respectively, were used as nanofillers to reinforce the CPI hybrid films.

Effects of diamine isomers on the properties of colorless and transparent copoly(amide imide)s.

To fully understand the structure-property relationship of aromatic copoly(amide-imide)s (Co-PAIs) and determine which factors lead to chain rigidity, we prepared two series of Co-PAIs. They were synthesized from two types of amine monomers containing - and -isomers and different ratios of 4,4'-(hexafluoroiso-propylidene)diphthalic anhydride (6FDA) and 4,4'-biphthalic anhydride (BPA). -Substituted and -substituted ,'-[2,2'-bis(trifluoromethyl)-4,4'-biphenylene]bis(aminobenzamide) (MPAB) diamine isomers were synthesized from 3- and 4-nitrobenzoyl chloride and 2,2'-bis(trifluoromethyl) benzidine (TFB), respectively.

Influence of hydroquinone content on thermotropic liquid crystalline copolymers and nanocomposites: thermo-mechanical properties and morphology.

Thermotropic liquid crystalline copolyesters (Co-TLCPs) were synthesized by varying the hydroquinone (HQ) molar ratio from 1-5 with respect to the 2,5-diethoxyterephthalic acid (ETA) monomer. The thermal properties and liquid crystalline mesophases of the synthesized Co-TLCP were investigated. All of the Co-TLCPs synthesized using a HQ molar ratio of 1-5 showed a nematic liquid crystalline phase.

Carbon Papers from Tall Goldenrod Cellulose Fibers and Carbon Nanotubes for Application as Electromagnetic Interference Shielding Materials.

To transform tall goldenrods, which are invasive alien plant that destroy the ecosystem of South Korea, into useful materials, cellulose fibers isolated from tall goldenrods are applied as EMI shielding materials in this study. The obtained cellulose fibers were blended with CNTs, which were used as additives, to improve the electrical conductivity. TGCF/CNT papers prepared using a facile paper manufacturing process with various weight percent ratios and thickness were carbonized at high temperatures and investigated as EMI shielding materials.

Fabrication and Characterization of Waste Wood Cellulose Fiber/Graphene Nanoplatelet Carbon Papers for Application as Electromagnetic Interference Shielding Materials.

Waste wood contains large amounts of cellulose fibers that have outstanding mechanical properties. These fibers can be recycled and converted into highly valuable materials of waste wood. In this study, waste wood cellulose fiber/graphene nanoplatelet (WWCF/GnP) papers were prepared according to the WWCF and GnP contents.

Comparison of Properties of Colorless and Transparent Polyimide Nanocomposites Containing Different Diamine Monomers.

To improve the optical properties of polyimide (PI) films, we prepared two series of colorless transparent PIs from the dianhydride 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and a diamine, either 2,2-bis(3-aminophenyl)hexafluoropropane (FDN) or 2,2-bis(3-amino-4-hydroxy-phenyl)hexafluoropropane (FDN-OH). Next, colorless PI (CPI) composite films were prepared by dispersing 0-1.00 wt % of organically modified clay (Cloisite 30B) in the intermediate poly(amic acid) (PAA) solution via solution intercalation, followed by imidization.

Electromagnetic Interference Shielding Behavior of Magnetic Carbon Fibers Prepared by Electroless FeCoNi-Plating.

In this study, soft magnetic metal was coated on carbon fibers (CFs) using an electroless FeCoNi-plating method to enhance the electromagnetic interference (EMI) shielding properties of CFs. Scanning electron microscopy, X-ray diffraction, and a vibrating sample magnetometer were employed to determine the morphologies, structural properties, and magnetic properties of the FeCoNi-CFs, respectively. The EMI shielding behavior of the FeCoNi-CFs was investigated in the frequency range of 300 kHz to 3 GHz through vector network analysis.

Thermotropic liquid crystalline copolyester fibers according to various heat treatment conditions.

Thermotropic liquid crystal copolyester (TLCP) was synthesized using a melt polymerization method, with a molar ratio composition of 2,5-diethoxy terephthalic acid (ETA), hydroquinone (HQ), and p-hydroxybenzoic acid (HBA) of 1:1:3. TLCP exhibited nematic liquid crystalline mesophase and maintained nematic textures under all heat treatment conditions applied. The synthesized TLCP was processed into fibers using a capillary rheometer.

Preparation and Characterization of Carbon Fibers from Lyocell Precursors Grafted with Polyacrylamide via Electron-Beam Irradiation.

Carbon fibers, which act as reinforcements in many applications, are often obtained from polyacrylonitrile (PAN). However, their production is expensive and results in waste problems. Therefore, we focused on producing carbon fibers from lyocell, a cellulose-based material, and analyzed the effects of the process parameters on their mechanical properties and carbon yields.

Analysis of Impact Characteristics and Detection of Internal Defects for Unidirectional Carbon Composites with Respect to Fiber Orientation.

With the increasing use of carbon fiber reinforced plastics in various fields, carbon fiber composites based on prepregs have attracted attention in industries and academia research. However, prepreg manufacturing processes are costly, and the strength of structures varies depending on the orientation and defects (pores and delamination). For the non-contact evaluation of internal defects, the lock-in infrared thermography was proposed to investigate the defects in the composites subjected to the compression after impact test (CAI).

Direct growth of flower like-structured CuFe oxide on graphene supported nickel foam as an effective sensor for glucose determination.

In this report, a novel flower like-structured CuFe oxides was directly grown on graphene nanosheets supported nickel foam substrates (CuFe-O/GR/NF) via a hydrothermal method followed by an additionally pyrolysis process. The different morphologies consistent with varied synthesis conditions, along with their catalytic activity were discussed. The CuFe-O/GR/NF material was successfully applied as an electrocatalyst for sensing glucose with a wide linear concentration range of 0.

Fabrication and Characterization of Carbon-Fiber-Reinforced Polymer-FeSi Composites with Enhanced Magnetic Properties.

In this work, we aimed to manufacture and characterize carbon-fiber-polymer-metal-particles magnetic composites with a sandwichlike structure. The composites were manufactured by stacking the plain woven carbon fiber prepregs (or carbon-fiber-reinforced polymers (CFRP)) and layers of the FeSi particles. The layer of FeSi particles were formed by evenly distributing the FeSi powder on the surface of carbon fiber prepreg sheet.