• Korean Journal of Materials Research
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• v.26 no.9
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• pp.478-485
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• 2016

An amide group was introduced to restrain the cohesion of silica nano-particles and copolymerized with polyamic acid. Amide block copolymers were prepared using silica and (3-mercaptopropyl) trimethoxysilane (MPTMS) with a siloxane group, using 2, 6-Lutidine as a catalyst. Amide block polymers and copolymers were synthesized via ATRP after brominating pyromellitic dianhydride (PMDA) and polyamic acid of methylene diphenyl diamine (MDA) using ${\alpha}$-bromo isobutyryl bromide. Characteristic peaks of copolymer with amide and imide groups and patterns of amorphous polymers were studied using FT-IR and XRD analyses; an analysis of the surface characteristic groups was conducted via XPS. Changes in the thermal properties were examined through DSC and TGA; solubility for solvents was also studied.

• Elastomers and Composites
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• v.51 no.2
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• pp.138-146
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• 2016

It is an inconvenience for silica nano-particles to dry again when using it in that they cohere each other through moisture in the air. Acrylamide groups were introduced to improve such inconvenience and copolymerized with silica nano-particles and then we copolymerized again with polyamic acid in order to increase thermal characteristic. Amide block copolymers were prepared using silica and (3-mercaptopropyl) trimethoxysilane (MPTMS) with a siloxane group, using 2,6-Lutidine as a catalyst. Amide block polymers and copolymers were synthesized via ATRP after brominating pyromellitic dianhydride (PMDA) and polyamic acid of methylene diphenyl diamine (MDA), using ${\alpha}$-bromo isobutyryl bromide. Characteristic peaks of copolymer with amide and imide groups and patterns of amorphous polymers were researched by FT-IR and XRD analyses and the analysis of surface characteristic groups was conducted via XPS. A change in thermal properties was examined through DSC and TGA and solubility for solvents was also researched.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.58-65
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• 1998

Substituted dicyandiamide(Sub-DICY), Accelerated dicyandiamide(Acc-DICY), Trimellitic anhydride(TMA), Pyromellitic dianhydride(PMDA) and Phenolic curing agent(Ph.C.A.) are mainly used for epoxy powder coating curing agent. Various characteristics of epoxy films fully cured by optimum condition such as mechanical properties like $T_g$, tensile strength, elongation at break hardness, abrasion resistance and chemical properties like water absorption, acid resistance, alkali resistance and electrical properties, corrosion resistance are determined by various measuring devices and analyses devices. In conclusion, phenolic curing agent was shown excellent thoughness but severe color change as temperature increased. Acid anhydride has excellent insulation properties and color stability at elevated temperature but lower thoughness and adhesion to substrate. DICY curing agent was shown high water absorption and severe color chance as temperature increased.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.2
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• pp.1-7
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• 1999

The polymide thin films were fabricated by vapor deposition polymerized method of dry processes and studied the electric breakdown characteristics by self healing method. Polyamic-acid(PAA) thin films prepared by vapor deposition-polymerization (VDP) from PMDA(Pyromellitic dianhydride) and DDE(4,4'-diaminodiphenyl ether) were changed to PI thin films by thermal curing. In the same sample, electric breakdown fields increase with increasing test number, and then saturated over test number of the 25th. When the curing temperatures were 200$^{\circ}C$, 250$^{\circ}C$, 300$^{\circ}C$ and 350$^{\circ}C$, the electric breakdown strengths of PI were 1.21MV/cm, 3.94MV/cm, 4.61MV/cm and 4.55MV/cm at the test number of 40th.

• Textile Coloration and Finishing
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• v.25 no.4
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• pp.247-253
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• 2013

The enzyme-like catalytic functions of metal complex phthalocyanine derivatives those containing carboxylic acid groups could be applied as odor-removing systems and antibacterial systems. Pyromellitic dianhydride and 4-nitrophthalimide were used as starting material for synthesizing dinitro-tetracarboxylic acid iron phthalocyanine(compound 1). Then diamino-tetracarboxylic phthalocyanine(compound 2) was obtained by reduction of compound 1. For the formation of covalent bond with cellulose fiber, cyanuric chloride was introduced to the amino group of compound 2 by condensation reaction compound 3. The exhaustion method was employed for adsorbing compound 3 on cotton fiber. K/S values of each fabrics were measured by a CCM system and deodorizing rates were tested by a detector tube method for ammonia gas. K/S values of treated cotton fiber with compound 3 were arranged from 2.1 to 4.2 at $90^{\circ}C$ of exhaustion temperature. Deodorizing rates provided result of 81%, 84%, 88%, 91%, by passing time of 30 min, 60 min, 90 min, 120 min, respectively.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.380-385
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• 1996

Thin films of polyamic acid(PAA) were fabricated by vapor deposition polymerization(VDP) from pyromellitic dianhydride(PMDA) and 4,4'-diamino diphenyl ether(DDE). Thin films of polyimide(PI) were obtained by curing PAA, and their dielectric properties have been measured. The uniform thin films of PI formed by curing PAA at 300 .deg. C for 1 hr. which was confirmed by Fourier transform Infrared spectroscopy(FT-IR) absorption at 720, 1380, 1780c $m_{-1}$. Relative permittivity and tan .delta. were 3.9 and 0.008 at 10kHz, respectively. (author). 8 refs., 11 figs., 1 tab.1 tab.

• Macromolecular Research
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• v.8 no.1
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• pp.19-25
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• 2000

Aromatic diamine monomers containing allylic ester linkage, 1,5-bis(4-aminobenzoate)-1,2,3,4-tetrahydronaphthalene (4-DABTN) and 1,5-bis(3-amin obenzoate)-1,2,3,4-tetrahydronaphthalene (3-DABTN) were synthesized through the reaction of 1,5-dihydroxy-1,2,3,4-tetrahydronaphthalene and 4- or 3-nitrobenzoly chloride. By the reaction of these diamines with pyromellitic dianhydride (PMDA) or 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), poly(amic acid)s were obtained. The inherent viscosities of the poly(amic acid)s were between 0.55 and 1.31 dL/g. The poly(amic acid)s were converted to polyimides by chemical imidization. The thermogravimetric analysis (TGA) thermograms of these polyimides showed temperatures of 5% weight loss between 323 and 389$^{\circ}C$ in nitrogen atmosphere. The model compound ,1,5-bis (4-nitrobenzoate)-1,2,3,4-tetrahydronaphthalene (4-DNBTN), was decomposed to 4-nitrobenzoic acid and 5-(4-nitrobenzoate)-3,4-dihydronaphthalene upon addition of CF$_3$COOH.

• Macromolecular Research
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• v.12 no.3
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• pp.263-268
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• 2004

We have synthesized a water-soluble polyimide precursor, poly(amic acid) amine salt (PAD), from pyromellitic dianhydride (PMDA), 4,4'-oxydianiline, and N,N -dimethylethanolamine (DMEA) and have investigated in detail its properties with respect to the degree of salt formation (D$\_$sf/). The maximum value of D$\_$sf/ we obtained upon precipitation of the precursor solution into acetone was 79%. We synthesized a PAD having a D$\_$sf/ of 100% (PAD100) by the solid state drying of an organic solution. The precursors showed different solubility depending on the D$\_$sf/ to make up to 4 wt% solutions in water containing a small amount of DMEA. PAD100 is completely soluble in pure water. We investigated the imidization behavior of PAD in aqueous solution using various spectroscopic methods, which revealed that PAD 100 has faster imidization kinetics relative to that of the poly(amic acid)-type precursors. The resulting polyimide films prepared from an aqueous precursor solution possess almost similar physical and thermal properties as those prepared from N-methyl-2-pyrrolidone(NMP) solution. Therefore, we have demonstrated that PAD can be used as a water-based precursor of polyimide; this procedure avoids the use of toxic organic solvents, such as NMP.

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.556-565
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• 2023

Fast industrial and agricultural expansion result in the production of heavy metal ions (HMIs). These are exceedingly hazardous to both humans and the environment, and the necessity to eliminate them from aqueous systems prompts the development of novel materials. In the present study, a UIO-66 (COOH)₂ metal-organic framework (MOF) containing free carboxylic acid groups was post-synthetically modified with L-glutamic acid via the solid-solid reaction route. Pristine and glutamic acid-treated MOF materials were characterized in detail using several physicochemical techniques. Single-ion batch adsorption studies of Pb(II) and Hg(II) ions were carried out using pristine as well as amino acid-modified MOFs. We further examined parameters that influence removal efficiency, such as the initial concentration and contact time. The bare MOF had a higher ion adsorption capacity for Pb(II) (261.87 mg/g) than for Hg(II) ions (10.54 mg/g) at an initial concentration of 150 ppm. In contrast, an increased Hg(II) ion adsorption capacity was observed for the glutamic acid-modified MOF (80.6 mg/g) as compared to the bare MOF. The Hg(II) ion adsorption capacity increased by almost 87% after modification with glutamic acid. Fitting results of isotherm and kinetic data models indicated that the adsorption of Pb(II) on both pristine and glutamic acid-modified MOFs was due to surface complexation of Pb(II) ions with available -COOH groups (pyromellitic acid). Adsorption of Hg(II) on the glutamic acid-modified MOF was attributed to chelation, in which glutamic acid grafted onto the surface of the MOF formed chelates with Hg(II) ions.

• Applied Biological Chemistry
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• v.32 no.1
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• pp.30-36
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• 1989

Some chelating agents are evaluated as an antioxidant for the autoxidation of soybean oil. Soybean oil is autoxidized under a mild condition (the flow rate of 67ml $O_{2}/min$ and $50^{\circ}C$). The antioxidant effect is measured by active oxygen method, and the spectral change of autoxidized soybean oil examined. The antioxidant effect of chelating agents is increased in order of diphenic acid, naphthoquinone, pyromellitic acid, quinolinic acid and naphthalic acid, and particularly the effect is low in diphenic acid and naphthoquinone. It is found that the effect is more clearly demonstrated by NMR rather than IR and UV and that the effect is dependent on the functional group and geometric molecular structure of chelating agents.