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2000
39.
Preparation and solubility in acid and water of partially deacetylated chitins
Yong-Woo Cho, Jinho Jang, Chong Rae Park, and Sohk-Won Ko
Biomacromolecules 2000, 1 (4),
609-614.
December 12, 2000
Abstract
Partially deacetylated chitins with different degrees of deacetylation (DD) were prepared by alkaline treatment under homogeneous conditions, and the effect of DD on their solubility was discussed in terms of crystal structure and mode of hydrogen bonding. With an increase in the treatment time, the DD of chitin increased proportionally. The chitin became soluble in dilute acetic acid at the DD of ca. 28% or over and soluble in water at the DD of ca. 49%. The solubility of the partially deacetylated chitins had a close relationship with their crystal structure, crystallinity, and crystal imperfection as well as the glucosamine content. The wide-angle X-ray diffractometry (WAXD) revealed that the chitin with ca. 28% DD retained the crystal structure of α-chitin with significantly reduced crystallinity and perfection of the crystallites. The water-soluble chitin of ca. 49% DD had a new crystal structure similar to that of β-chitin rather than either α-chitin or chitosan, suggesting that the homogeneous deacetylation transformed the crystal structure of chitin from the α to the β form. Some hydrogen bonds existing in raw α-chitin were found to be missing at a DD of ca. 49%.
DOI:
10.1021/bm000036j
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38.
New film-forming aromatic poly(amide-imide)s containing isoindoloquinazolinedione unit in the backbone. 2. Physical properties of the film cast from poly(BPDA-ODA-DACB)
Seog Joo Kang, Sung Il Hong, Chong Rae Park
Journal of Applied Polymer Science 2000, 78 (1),
118-123.
October 3, 2000
Abstract
New aromatic poly(amide-imide) films containing isoindoloquinazolinedione unit in the backbone chain were directly obtained by thermal cyclization of the prepolymer of poly(amic acid-carbonamide) type, i.e., poly(biphenylphthalic dianhydride-oxydianiline-4,4′-diamino-3′-carbamoyl-benzanilide) [poly(BPDA-ODA-DACB)]. The films, before heat treatment, exhibited the tensile strength of 30 ≈ 40 MPa and the tensile modulus of 1.3 ≈ 1.9 GPa. After heat treatment, the strength and modulus increased to 135 ≈ 150 MPa and 2.6 ≈ 2.7 GPa, respectively. The films remained transparent throughout the thermal treatment. The cyclized films were much more chemically resistant to alkali than the commercial products such as “Kapton” film and “P84” film, while thermal properties were comparable. The isoindoloquinazolinedione unit induced in the chain backbone on the heat treatment of the films was considered to be a major factor responsible for the superior physical properties of the films.
DOI:
10.1002/1097-4628(20001003)78:1<118::AID-APP150>3.0.CO;2-7
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37.
Preparation and properties of activated carbon fabric from acrylic fabric waste
So Young You, Yun Heum Park, Chong Rae Park
Carbon 2000, 38 (10),
1453-1460.
October 1, 2000
Abstract
With the aim of developing a cheap but high performance activated carbon fabric, acrylic fabric wastes were reused to produce an activated carbon fabric. The precursor fabric was stabilized in the condition of as-obtained at 250°C for 5 h to get the degree of stabilization of 79%. The stabilized fabric was subsequently carbonized with stepwise sequential heat treatment, denoted as the sequential multistage carbonization technique, followed by activation with steam. The specific surface area and the total pore volume changed little through stabilization and sequential multistage carbonization while the total weight loss increased almost linearly with the increase of heat treatment temperature. When the carbonized fabric was activated at 900°C for 5 min, both the specific surface area and the total pore volume increased abruptly to 2400 m2/g and 1.15 cm3/g, respectively. We also obtained the iodine number of 1800 mg/g, methylene blue number of 300 mg/g, and benzene adsorptivity of about 54%. All these performances of the prepared PAN-based ACFs are superior to those of conventional commercial PAN-based ACFs.
DOI:
10.1016/S0008-6223(99)00278-X
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36.
Preparation and properties of aromatic polyamide homologs containing chlorine substituents
Seog Joo Kang, Sung Il Hong, Chong Rae Park
Journal of Applied Polymer Science 2000, 77 (6),
1387-1392.
August 8, 2000
Abstract
In order to study systematically the effect of halogen substituents on both the solubility and the thermal stability of aromatic polyamides, new diamine monomers have been synthesized by introducing chlorine groups onto various positions of 4,4′-diaminobenzanilide for the preparation of chlorinated aromatic polyamides. The monochlorinated aromatic polyamides, i.e., P-LCl and P-RCl, exhibited liquid crystalline property in 100% sulfuric acid solution in the temperature range from 40 and 60°C. However, the dichlorinated sample, i.e. P-LRCl, did not exhibit the liquid crystalline property due to the bulkiness of two chlorine groups. Both P-LCl and P-RCl exhibited unimodal decomposition behavior in contrast to the chlorinated poly(p-phenylene terephthalamide) (PPTA) that has been known to show bimodal decomposition behavior. The decomposition onset temperature of both P-LCl and P-RCl was 567°C, which was higher than 549°C of unchlorinated polyamide, P-NCl, but the same as that of PPTA. The char yield was about 50% for both P-LCl and P-RCl and higher than 40% of both PPTA and P-NCl. In the case of P-LRCl, the decomposition onset temperature was 480°C, but the highest char yield of 60% was obtained.
DOI:
10.1002/1097-4628(20000808)77:6<1387::AID-APP26>3.0.CO;2-6
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35.
Preparation and properties of a new aromatic polyamide with an ethoxycarbonyl pendant group: Poly(4,4'-diamino-2'-ethoxycarbonyl-benzanilide terephthalamide)
Seog Joo Kang, Sung Il Hong, Chong Rae Park
Journal of Polymer Science Part A-Polymer Chemistry 2000, 38 (6),
936-942.
March 15, 2000
Abstract
A new aromatic polyamide containing a pendant ethoxycarbonyl group was successfully synthesized from the reaction between 4,4′-diamino-2′-ethoxycarbonylbenzanilide and terephthaloyl chloride. The new polymer was soluble in organic solvents such as N-methyl-2-pyrrolidone and dimethylacetamide, and a tough and transparent film was cast from the polymer solution with viscosities ranging from 2.6 to 5.6 dL/g. When the polymer film was heat-treated at a temperature greater than 300 °C, a cyclization reaction occurred between the ethoxycarbonyl group and the adjacent amide bond to form a benzoxazinone unit in the polymer backbone. The thermal decomposition onset temperature of the cyclized film was about 523 °C, which was somewhat lower than that of poly(p-phenylene terephthalamide) (PPTA; 566 °C); however, the decomposition rate was slower than that of PPTA to yield a higher char residue. The dispersion temperature of the uncyclized poly(4,4′-diamino-2′-ethoxycarbonylbenzanilide terephthalamide) (PDEBTA) was about 340 °C, whereas that of the cyclized PDEBTA was not clear.
DOI:
10.1002/(SICI)1099-0518(20000315)38:6<936::AID-POLA2>3.0.CO;2-6
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34.
Preparation and physical properties of poly(4,4 '-diamino-3 '-carbamoylbenzanilide terephthalamide) and poly(4,4 '-diamino-3 '-carbamoylbenzanilide isophthalamide) films
Seog Joo Kang, Sung Il Hong, Chong Rae Park
Journal of Polymer Science Part A-Polymer Chemistry 2000, 38 (4),
775-780.
February 15, 2000
Abstract
To prepare thermally stable and high-performance polymeric films, new solvent-soluble aromatic polyamides with a carbamoyl pendant group, namely poly(4,4′-diamino-3′-carbamoylbenzanilide terephthalamide) (p-PDCBTA) and poly(4,4′-diamino-3′-carbamoylbenzanilide isophthalamide) (m-PDCBTA), were synthesized. The polymers were cyclized at around 200 to 350 °C to form quinazolone and benzoxazinone units along the polymer backbone. The decomposition onset temperatures of the cyclized m- and p-PDCBTAs were 457 and 524 °C, respectively, lower than that of poly(p-phenylene terephthalamide) (566 °C). For the p-PDCBTA film drawn by 40% and heat-treated, the tensile strength and Young's modulus were 421 MPa and 16.4 GPa, respectively. The film cyclized at 350 °C showed a storage modulus (E′) of 1 × 1011 dyne/cm2 (10 GPa) over the temperature range of room temperature to 400 °C.
DOI:
10.1002/(SICI)1099-0518(20000215)38:4<775::AID-POLA13>3.0.CO;2-N
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33.
Properties of molecular composite film of poly(4,4 '-diamino-2 '-carbamoylbenzanilide terephthalamide)(p-PDCBTA) and poly(4,4 '-diamino-2 '-chlorobenzanilide terephthalamide) (P-LCI)
Seog Joo Kang, Sung Il Hong, Chong Rae Park
Polymer Bulletin 2000, 43 (6),
505-510.
January 1, 2000
Abstract
A new thermally stable, high strength and high modulus aromatic polyamide film was obtained via the formation of the molecular composite of p-PDCBTA and P-LCl. The two polymers exhibited good miscibility identified with the measurement of dynamic mechanical property and FTIR spectra. By the combination of drawing by 40% and subsequent heat treatment, the tensile property of the composite film could be achieved to the strength of 450 MPa and the modulus of 24 GPa, which were sustainable upto 400 °C.
DOI:
10.1007/s002890050008
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32.
Sequence Structure and Thermal Property of Poly(butylene terephthalate) (PBT)/p-Acetoxybenzoic Acid(ABA) Copolymers Obtained Through Melt Trans-esterification Reactio
Do Gyung Kim, Soo Young Park, Chong Rae Park
Polymer-Korea 2000, 24 (1),
58-64.
January 1, 2000
Abstract
Poly(butylene terephthalte-co-oxybenzoate) (PBOT) was synthesized by melt trans-esterification of poly(butyldne terephthalate(PBT) and p-acetoxybenzoic acid(ABA)at 250, 260, and 270 ℃ with the compositions of PBT/ABA of 4/6, 5/5, 6/4. The sequence analysis of PBOT with a 1H FT-NMR indicated that the number of consecutive oxybenzoate units range from 1.2 to 1.5, which is larger than that of the corresponding poly(ethylene terephthalate)(PET)/ABA(PEOT) obtained at the same reaction conditions as the PBOT. The difference in the block length influenced the thermal degradation behavior: Polyoxybenzoate(POB), PBT and PBOT showed one-step degradation whereas PBOT exhibited two-step degradation. THe results suggested that PBOT consisted of three phases of PBT-rich phase, random phase of PBT andABA, and ABA-rich phase.
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31.
Kinetic Consideration of Melt-copolymerization of Poly(butylene terephthalate) (PBT) and p-Acetoxybenzoic Acid (ABA)
Do Gyung Kim, Soo Young Park, Chong Rae Park
Polymer-Korea 2000, 24 (1),
16-22.
January 1, 2000
Abstract
Poly(butylene terephthalate-co-oxybenzoate)(PBOT) containing mesogenic oxybenzoate units in the main chain was synthesized through ester exchange reaction by melt mixing of poly(butylene terephthalate)(PBT) and p-acetoxybenzoic acid(ABA). From the kinetics of the copolymerization reaction, the activation energies and the rate constants of homopolymerization and copolymerization, kb and kc, could be determined. From the reaction conditions of different compositions, 4/6, 5/5, and 6/4 of PBT/ABA, at 250, 260, and 270 ℃, it was revealed that copolymerization between PBT and ABA proceeds on a pseudo-second order reaction if the ABA content and its conversion are low. In this case, the ratio of rate constants of homopolumerization to copolymerixation was in the range from 1.08 to 3.17, indicating that the copolymer with more notable block character was obtained at the higher mole fraction of ABA and at higher temperature.
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1999
30.
[특집]
The Eco-labelling Scheme for Textile Products-Present Position and Prospects
Eun Kyung Choe, Eun Jong Son, Sang Yong Kim, Chong Rae Park
Fiber Technology and Industry 1999, 3 (3~4),
85-103.
March 1, 1999
*Domestic Journal Article
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29.
[특집]
High Performance Fiber Reinforcements for Advanced Composites
Chong Rae Park
Polymer Science and Technology 1999, 10 (1),
55-64.
January 1, 1999
*Domestic Journal Article
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1998
28.
Monte Carlo simulation of copolymerization by ester interchange reaction in miscible polyester blends
Seung Soon Jang, Wan Shik Ha, Won Ho Jo, Ji Ho Youk, Jun Ho Kim, Chong Rae Park
Journal of Polymer Science Part B-Polymer Physics 1998, 36 (10),
1637-1645.
July 30, 1998
Abstract
The effects of reaction variables on the degree of randomness in copolymers formed by ester interchange reaction in miscible polyester melt blends were systematically investigated using a Monte Carlo method. Three reaction variables such as the molecular weight difference between two component polymers, the blend ratio, and the reaction ratio of end attack to bond flip, were particularly considered on the cubic lattice model. Ester interchange reactions were assumed to take place during reptational chain motions. It was found that the copolymerization was dependent upon the molecular weight difference and reaction ratio: As the molecular weight difference becomes smaller and when both end attack and bond flip reactions are involved simultaneously, the copolymerization is accelerated. However, the blend ratio does not affect the copolymerization process. This result is discussed in relation to the polymer chain conformation for the ester interchange reaction.
DOI:
10.1002/(SICI)1099-0488(19980730)36:10<1637::AID-POLB5>3.0.CO;2-M
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27.
Development of High Temperature Filter Media Based on Textile Wastes (2) -Adsorption Behavior of Activated Carbon Fabrics Based on Acrylic Wastes-
So Young You, Chang Hun Yun, Yun Heum Park, Chong Rae Park
Journal of Korean Fiber Society 1998, 35 (7),
402-411.
July 1, 1998
*Domestic Journal Article
Abstract
Activated carbon fabrics were prepared by activating the acrylic waste fabrics containing methylacrylate (MA) only as the comonomer. The stabilization, carbonization and activation processes were monitored in terms of the changes in the chemical composition, density and activation yield. Whereas the newly prepared activated carbon fabric showed somewhat inferior specific surface area, iodine adsorption and methylene blue adsorption capacities to a foreign commercial activated carbon fiber nonwovens based on polyacrylonitrile, its performance is comparable to the active carbon granules of the first grade.
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26.
A Monte Carlo Simulation of Ester Interchange Reaction in Miseible Polyester Blends
Ji Ho Youk, Seung Soon Jang, Chong Rae Park, Won Ho Jo
Polymer-Korea 1998, 22 (4),
651-658.
July 1, 1998
Abstract
The effects of ester interchange reaction parameters, such as type of interchange reaction mechanism (end-attack or direct interchange), blend ratio, and reactivity ratio of reacting polyesters on the polydispersity index and the degree of randomness (DR)
were simulated using a Monte Carlo method. The initial increasing rates of polydispersity and DR were linearly increased and linearly decreased, respectively, with the fraction of end-attack reaction in ester interchange reaction. The characteristic of the two interchange reaction mechanisms was discussed in terms of the fraction of reactions increasing, decreasing and not changing the DR with the number of reaction per segment. The DR was independent of the blend composition. The equilibrium values of DR were not 1.0 when the reactivity ratio between two reacting polyesters deviated from unity, while the initial increasing rate of DR was independent of the reactivity ratio.
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25.
Development of High Temperature Filter Media Based on Textile Wastes (1) -Thermal Stabilization Mechanisms of Waste Acrylic Fabric Containing Methylacrylate only as the Comonomer-
So Young You, Chang Hun Yun, Yun Heum Park, Chong Rae Park
Journal of Korean Fiber Society 1998, 35 (6),
351-361.
June 1, 1998
*Domestic Journal Article
Abstract
Thermal stabilization mechanisms of a waste acrylic fabric containing methylacrylate (MA) only as the comonomer were studied using differential scanning calorimetry (DSC) and subsequent Fourier transform infrared spectroscopy (FTIR). It has been found first that the thermal stabilization behavior of the waste fabric containging :VIA depends on the heating rate and environmental atmospheric condition : atmosphere and the slow heating rate (e.g. 2 'C/min) produce double exotherms whereas the nitrogen atmosphere and fast heating rate(e.g. 10 'C/min) result in a single exotherm. The different thermal behaviO{ is explained with the newly established stabilization mechanisms which are extracted from the computer analysis of the FTIR spectral changes based on the curve fitting and curve-resolution techniques.
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24.
A Study on the Permanent Set of Wool Fabric by Utilizing Natural Protein Polymers (1) -Adsorption Behavior of Hydrolyzed Wool Keratins onto Wool Fabrics-
Mun Seb Hwang, Yun Heum Park, Boong Soo Jeon, Chong Rae Park, Kuen Yong Lee, Myung Hack Lee, Heung Su Park, Yong Ju Cho
Journal of Korean Fiber Society 1998, 35 (5),
314-320.
May 1, 1998
*Domestic Journal Article
Abstract
Adsorption behavior of hydrolyzed wool keratins onto wool fabric was first studied systematically for the purpose of improving the permanent set of a wool fabric. The adsorption isotherm of the kera tin onto wool fabric sho1red a Langmuir type and was found to be influenced by pretreatments such as swelling and reduction of wool fabric. Indeed, by the reduction, the diffusion coefficient of the hydrolyzed keratin was increased by about 10 times as large as that of the untreated wool fabric. It was indicated from the solubility test and washing test that new crosslinks were possibly formed h!' the adsorption of keratin and the subsequent oxidation. Dyeing behavior of the keratin adsorbed wool fabric was also discussed in terms of the adsorbed amount of hydrolyzed keratin.
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1997
23.
Effect of chemical structure on crystallization behavior of poly(phenylene alkylene dicarboxylate) (PPAD)
Ji Ho Youk, Wan Shik Ha, Won Ho Jo, Chong Rae Park
Journal of Applied Polymer Science 1997, 66 (8),
1575-1582.
November 21, 1997
Abstract
Various poly(p-phenylene alkylene dicarboxylates) (PPADs) were synthesized and their crystallization behavior was examined as functions of the length and the odd/even numbers of carbon atoms in the aliphatic component. PPADs with longer aliphatic units of even-numbered carbon atoms were found to crystallize faster than do those of other cases. The results are compared with the crystallization behavior of conventional poly(alkylene terephthalate)s (PATs), e.g., poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT), which have the same chemical composition as the corresponding PPAD but the reversed direction of the ester group. The effects of this structural difference on the melting temperature and the crystallization kinetics are also discussed.
DOI:
10.1002/(SICI)1097-4628(19971121)66:8<1575::AID-APP19>3.0.CO;2-2
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22.
A study on the ester interchange reaction between poly(ethylene terephthalate) and poly(ethylene naphthalate)
Woo Sung Kim, Ji Ho Youk, Wan Shik Ha, Soo Young Park, Chong Rae Park
Polymer-Korea 1997, 21 (5),
794-802.
September 1, 1997
Abstract
The effect of two ester interchange reactions, end-attack and direct interchange, on the polydispersity index and the degree of randomness in the copolymer of poly (ethylene terephthalate) (PET)/poly(ethylene naphthalate) (PEN) was systematically investigated using both computer simulation and experimental methods. It is revealed from the computer simulation that the end-attack reaction leads the polydispersity index much rapidly to the equilibrium value at about 2 while direct interchange reaction brings the degree of randomness much effectively to the equilibrium value at about l. It was experimentally confirmed from the ester interchange reaction in the pairs, i.e. PET/PEN, 8-PET/PE:N, PET/ 8-PEN. B-PET/8-PEN that end-attack reaction was much more dominant than the direct interchange reaction.
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21.
New modified poly(ethylene terephthalate) (MPET)-based adsorbent for heavy metal ions
Yun Heum Park, Jeong Mook Lim, Chong Rae Park
Journal of Applied Polymer Science 1997, 63 (6),
773-778.
February 7, 1997
Abstract
Modified poly(ethylene terephthalate) (MPET) samples of both powder and fiber types, which contain sodium 5-sulfodimethyl isophthalate as the third comonomer component, were explored as an adsorbent for the elimination of heavy metal ions, e.g., Cr3+, Pb2+, and Cd2+, in wastewater. The ions were preferentially adsorbed on finer particles at a lower temperature and pH 4 and were exothermically chemisorbed onto the MPETs via an ionic interaction. It was also found that among the ions Cr3+ is the most preferentially adsorbed, followed by Pb2+ and Cd2+ ions and the adsorption capability of MPETs increased considerably with the presence of phenol. The separation factor indicated that the MPET fiber wastes may possibly be reutilized as an economical adsorbent for heavy metal ions in wastewater.
DOI:
10.1002/(SICI)1097-4628(19970207)63:6<773::AID-APP9>3.0.CO;2-K
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20.
Preparation of poly(ethylene terephthalate-co-isophthalate) by ester interchange reaction in the PET/PEI blend system
Wan Shik Ha, Yong Kun Chun, Seung Soon Jang, Do Mook Rhee, Chong Rae Park
Journal of Polymer Science Part B-Polymer Physics 1997, 35 (2),
309-315.
January 30, 1997
Abstract
Optimum conditions for the synthesis of PEI of considerable molecular weight have been established. Poly(ethylene terephthalate-co-isophthalate) (PETI) has been prepared through the ester interchange reaction of a blend of poly(ethylene terephthalate) (PET) and poly(ethylene isophthalate) (PEI). NMR analysis has indicated that the PETI changes from a block-type copolymer to a random type copolymer as the ester interchange reaction proceeds. If the reaction is limited to 20 min, the resulting PETI is crystallizable. The effects of catalysts that have been used during the synthesis of PEI on the characteristics of PETI are also discussed.
DOI:
10.1002/(SICI)1099-0488(19970130)35:2<309::AID-POLB8>3.0.CO;2-M
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19.
Molecular Structural Defects in High Molecular Weight Polyacrylonitrile Prepared in Aqueous Sodium Thiocyanate Solution
Jeong Ki Kim, Chong Rae Park, Yun Heum Park, Byung Ghyl Min, Tae Won Son, Joo Hwan Ryu
Journal of Korean Fiber Society 1997, 34 (1),
49-53.
January 1, 1997
*Domestic Journal Article
Abstract
Studied is the applicability of Patron and Bastianeli's polymerization condition[6] i.e. high monomer and low initiator concentrations. to the polymerization of AN in 51.5% aqueous sodium thiocyanate solution with very low cham transfer constant of the order of 10-7 Although Parton and Bastianeli's condition is known to produce polyacrylonitriles(PANs) with defect free structures in organic solvents such as ethylene carbonate(EC)/propylene carbonate(PC) with a relatively high chain transfer constant of the order of 10 ', it is found from this work that, if the polymerization reaction is carried out at a conventional polymerization temperature, e.g. 55"C, the condition is not helpful even in the inorganic solvent to suppressing the formation of the defect structures such as keteneimine and enaminonitrile in a linear high molecular weight PAN. The possible overestimation of molecular weight of PAN due to the molecular defect structures is questioned.
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1996
18.
[기술해설]
Textile Materials as Environmental Problem Sovers(Green Tex): Activated Carbon Fiber
Chong Rae Park, Seog Joo Kang
Journal of Korean Fiber Society 1996, 33 (12),
1148-1156.
December 1, 1996
*Domestic Journal Article
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17.
Mechanism of Structural Transformation by Heat Treatment of Poly(biphenylphthalic dianhydride-oxydianiline-4,4'-diamino-3'-carbamoylbenzanilide) (Poly(BPDA-ODA-DACB))
Seog Joo Kang, Chong Rae Park
Journal of Korean Fiber Society 1996, 33 (11),
1004-1008.
November 1, 1996
*Domestic Journal Article
Abstract
In order to clarify the thermal cyclization mechanism for the introduction of isoindoloquinazolinedione(IQ) unit in the backbone of poiyimides. three model compounds I, Il, and Ill of poly(biphenyiphthalic dianhydridc-oxydianiline-4,4'-diamino-3'-carbamoylbenzanilide) (Poly(BPDA-ODA-DACB)) have been synthesized. It has been found that two possible mechanisms are operating during the structural change by heat treatment of the model compound; one is the formation of quinazolone ring first, i.e. the compound IV. followed by the formation of IQ unit, i.e. the compound VI. and the other is the formation of imide ring, i.e. the compound V. precedes the formation of IQ ring structure, i.e. the compound VII, which finally transforms to more stable IQ structure i.e. the compound VI on further heat treatment at high temperatures. It turns out that a gradual heat treatment favors the second reaction mechanism.
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16.
Effect of Surface Treatment on the Morphology and Mechanical Behavior of Torayca T300 Carbon Fiber
Chong Rae Park, Soonho Lim, Joon Seok Lee
Journal of Korean Fiber Society 1996, 33 (11),
997-1003.
November 1, 1996
*Domestic Journal Article
Abstract
The effect of surface treatment at high temperatures on the morphology and mechanical behavior of Torayca T300 carbon fiber is studied. It is found that the surface treatment results in a considerable change in the surface and cross-sectional morphology of the carbon fiber. Accordingly, there arc sizable change in mechanical properties of the fiber: in particular, compressional failure mechanism changes from buckling to simple shear mode as the surface treatment temperature increases. There is not an apparent relationship between the surface structural parameters such as surface area, pore volume, etc. and the mechanical properties such as tensile and compressive strengths.
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15.
Preparation and properties of conducting arachidic acid/polypyrrole composite Langmuir-Blodgett films
Yun Heum Park, Seong Yoon Park, Sung Woo Nam, Chong Rae Park, Young Jun Kim
Journal of Applied Polymer Science 1996, 60 (6),
865-870.
May 9, 1996
Abstract
Electrically conducting arachidic acid/polypyrrole (PPy) composite films were prepared by exposing the arachidic acid LB films containing ferric chloride to pyrrole vapor. The optimum conditions to deposit matrix LB film were the subphase temperature of 23–25°C, pH of 6.0 and ferric chloride concentration of 5.0 × 10−5M. The formation of PPy in the arachidic acid matrix LB films was confirmed by UV-visible spectra, FTIR spectra, and scanning electron micrographs. The average thickness of the composite LB films prepared at 0°C was 1525 Å. The composite films prepared at lower temperatures have more uniform surface and exhibit higher electrical conductivity than the films prepared at higher temperatures do. The in-plain conductivity and the transverse conductivity of the composite film were 10−3−10−2 S/cm and 10−6S/cm, respectively, and, thus, the conductivity anisotropy was about 103
DOI:
10.1002/(SICI)1097-4628(19960509)60:6<865::AID-APP9>3.0.CO;2-H
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14.
[특집]
Activated Carbon Fibers as a Pioneering Problem Solver of Environmental Problems
Chong Rae Park, Seog Joo Kang, Chang Hun Yun
Polymer Science and Technology 1996, 7 (2),
130-139.
April 1, 1996
*Domestic Journal Article
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13.
[고분자분석기술 지상강좌]
Scanning Electron Microscopy and X-ray Microanalysis of Polymeric Materials
Chong Rae Park
Polymer Science and Technology 1996, 7 (1),
75-85.
February 1, 1996
*Domestic Journal Article
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1995
12.
Structure-compressional property relations in carbon fibres
M.G. Dobb, H. Guo, D.J. Johnson, C.R. Park
Carbon 1995, 33 (11),
1553-1559.
November 1, 1995
Abstract
Microstructural features of carbon fibres based on both polyacrylonitrile (PAN) and mesophase pitch (MP) are discussed in relation to their compressional performance estimated by the recoil test. The compressive strength of carbon fibres is influenced by a combination of various structural features and not by any single feature. In particular, the compressive failure strength increases linearly with increasing amounts of both inter- and intracrystalline disorder. For a given amount of disorder, the more recently developed PAN-based fibres exhibited much higher compressive failure stresses than older PAN- and MP-based carbon fibres; this is due to the more homogeneous distribution of microstructural features. In order to promote compressive strength it is suggested that all crystallite dimensions should be limited to below 5 nm whilst maintaining good orientation.
DOI:
10.1016/0008-6223(95)00114-S
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1994
11.
Relationship between Characteristics and Thermal Behavior of DMSO-Solution Polymerized PANs
Byung Ghyl Min, Byoung Chul Kim, Chul Joo Lee, Tae Won Son, Chan Ho Ahn, Chong Rae Park, Yun Heum Park, Soon Sik Kim
Journal of Korean Fiber Society 1994, 31 (12),
983-992.
December 1, 1994
*Domestic Journal Article
Abstract
For both polyacrylonitrile homopolymer and copolymers(homo- and co-PANs) prepared in dimethylsulfoxide(DMSO) solution by radical polymerization induced by azo-bis-isobutyronitrile(AIBN), the thermal
behavior studied via DSC technique was discussed in relation to the characteristics of polymers. It has been
found that for the non-isothermal stabilization of homo-PANs under nitrogen and air atmospheres. the initiation and the maximum temperatures for the stabilization are not influenced by molecular weight and
molecular weight distribution characteristics of polymers. However, under isothermal stabilization under air, longer time is required by the polymers with higher content of high molecular weight fraction, i.e. Mw > 3x10^5. It has also been confirmed that the addition of comonomer and air atmosphere favour the stabilization of polymers by lowering the intiation temperature, slowing down the reaction rate, and extending the temperature range within which the stabilization may be completed. From the isothermal stabilization of co-PANs. it
was believed that the temperature of 240oC have practical significance.
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10.
Polymerization Behavior of AN in DMSO Solution
Chan Ho Ahn, Chong Rae Park, Yun Heum Park, Byung Gil Min, Tae Won Son
Journal of Korean Fiber Society 1994, 31 (11),
894-903.
November 1, 1994
*Domestic Journal Article
Abstract
For both homo-and co-polyacrylonitriles(homo- and co-PAN) prepared in dimethylsulfoxide(DMSO) solution by radical polymerization induced by azo-bis-isobutyronitrile(AIBN), the reaction kinetics was studied. It has been found that the polymerization rate increases with increasing concentrations of monomer and initiator, and the polymerization temperature, while molecular weight, polydispersity, and high molecular-weight-fraction(over 3x10^5 in Mw) decrease.
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9.
Studies on the On-line Dry-Jet Wet Spinning of Polyacrylonitrile (1) -Design Factors of Polymerization to Match Desired Spinnability-
Byung Ghyl Min, Byoung Chul Kim, Chul Joo Lee, Tae Won Son, Chan Ho Ahn, Chong Rae Park, Yun Heum Park, Soon Sik Kim
Journal of Korean Fiber Society 1994, 31 (8),
602-607.
August 1, 1994
*Domestic Journal Article
Abstract
The polymerization factors to meet the desired physical properties of polyacrylonitrile (PAN) spinning dope for on-line spinning were examined, The spinning dope was prepared by solution polymerization in
dimethylsulfoxide solution induced by azobis-iso-butyronitrile. The physical properties of the spinning dope
could be controlled by manipulating monomer concentration, initiator concentration, and polymerization temperature.
At the unusually high monomer concentrations, required in the on-Iine spinning process, the polymerization of PAN exhibited a little deviation from the theoretical prediction
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8.
Tensile-Recoil-Compressional Behaviour of Kevlar Fibers
Chong Rae Park
Journal of Korean Fiber Society 1994, 31 (6),
459-464.
June 1, 1994
*Domestic Journal Article
Abstract
The compressional behaviour of Kevlar type aramid fibres i.e. Kevlar 49, Kevlar 981, and Kevlar 149 has been studied by means of a single-fibre-recoil test method followed by scanning electron microscope (SEM) examination. The poor compressive strengths of the fibres examined are considered due to the high degree of order and their inherent pleated sheet like structures which originate from the features of nematic liquid crystalline. SEM micrographs of compressed fibres show somewhat different types of failure depending on the types of the fibres and the supporting environment around the fibres. Namely the fibres with a surrounding support exhibit essentially the formation of kink bands due to Euler bending. The difference in failure mechanisms is discussed in terms of the structural characteristics of fibre variants.
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1993
7.
[기술해설]
High Functionalization of Polyester Fibers through Physical and Chemical Modifications (2)
Tae Whan Ahn, Chong Rae Park, Yun Heum Park
Journal of Korean Fiber Society 1993, 30 (9),
617-628.
September 1, 1993
*Domestic Journal Article
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6.
[기술해설]
High Functionalization of Polyester Fibers through Physical and Chemical Modifications (1)
Tae Whan Ahn, Chong Rae Park, Yun Heum Park
Journal of Korean Fiber Society 1993, 30 (6),
403-411.
June 1, 1993
*Domestic Journal Article
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1992
5.
Preparation of Antistatic Polyester Materials and Their Properties (2) -Electrical Properties-
Yun Heum Park, Hak Soo Park, Chong Rae Park
Journal of Korean Fiber Society 1992, 29 (12),
921-929.
December 1, 1992
*Domestic Journal Article
Abstract
Various electrical properties such as electrical conductivity, electrostatic charge and its half-life time, and electromagnetic shielding effetiveness were studied for antistatic polyester film and fabric prepared by exposing modified poly( ethylene terephtalate) (M -PET) containing ferric chloride as an oxidant to pyrrole vapor. Higher content of FeCl3 led to higher eletrical conductivity, however shorter time to the saturation conductivity. It was found that just above the critical polypyrrole(PPy) content, 1.5wt% , electrical conductivity increased rapidly to the saturation value, 10^-3 S/cm. Morphological feature of the antistatic film, i. e. homogeneous and dense distribution of PPy on the film surface, was found to be another preferential factor improving the electrical conductivity. The initial electrical conductivity of antistatic film was retained even after 30 days at room temperature under atmospheric environment. As compared with the M-PET fabric itself, the antistatic fabric was found to have lower maxium electrostatic charge by about three orders and shorter half-life time by about two orders. Also the antistatic fabirc exhibited good electromagnetic shielding effectiveness which read 24 dB at 300 MHz.
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4.
Role of microvoids in aramid fibres
M. G. Dobb, C. R. Park, R. M. Robson
Journal of Materials Science 1992, 27 (14),
3876-3878.
July 15, 1992
Abstract
The distribution of microvoids in high-strength aramid fibre has been established. The tensile and compressive behaviours of both untreated and silver sulphide-impregnated Kevlar 981 fibre are reported and the results are discussed in terms of the influence of microvoids on the mechanical performance.
DOI:
10.1007/BF00545470
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3.
Preparation of Antistatic Polyester Materials and Their Properties (1) -Characterization-
Yun Heum Park, Hak Soo Park, Sung Woo Nam, Chong Rae Park
Journal of Korean Fiber Society 1992, 29 (7),
512-520.
July 1, 1992
*Domestic Journal Article
Abstract
Modified polyethylene terephtale (M-PET) was obtained by copolymerizing dimethyl terephtalate(DMT), ethylene glycol, and dimethyl 5-sulfoisophthalate(DMS) and antistatic polyester material has been prepared by exposing M-PET containg ferric chloride to pyrrole vapor. The DMS component in M-PET was confirmed by the analysis of IR and NMR spectra. The formation of polypyrrole(PPy) in M-PET matrix was also confirmed by the analysis of IR spectrum. The changes of physical structure due to the insertion of ferric chloride and formation of PPy in M-PET have been investigated by analysing wide-angle X-ray diffraction curves. The surface of the antistatic polyester film showed the continuous phase of granular PPy which was formed through the film thickness The physical properties of antistatic polyester was satisfiable, that was, the tensile strength and the elongation at break retained 80 and 90% of those of M-PET matrix, respectively. But the modulus retained about 60% of M-PET matrix.
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1990
2.
Compressional behavior of carbon fibers
M.G. Dobb, D.J. Johnson and C.R. Park
Journal of Materials Science 1990, 25 (2A),
829-834.
February 1, 1990
Abstract
The compressional behaviour of polyacrylonitrile (PAN)-based and mesophase-pitch (MP)-based carbon fibres has been studied by means of a single-fibre-recoil test method followed by scanning electronn microscope (SEM) examination. PAN-based carbon fibres have relatively high compressive strengths compared with MP-based carbon fibres. The improved tensile and compressive strengths of some recent PAN-based fibres are discussed in terms of a two-phase structure; one phase is the normal layer-plane structure, the other phase is a disordered carbon structure. The relatively low compressive strengths of the MP-based fibres are considered to be due to the high degree of order (graphitization) and their inherent sheet-like structure. SEM micrographs of compressed fibres show different types of failure depending upon the origin of the fibres. Consequently, two different mechanisms of deformation have been proposed, namely the formation of multiple kink bands associated with bending in the case of PAN-based fibres, and a single kink band associated with classical shear failure in the case of most MP-based fibres.
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1982
1.
[총설]
양모에의 그라프트 반응
Jong Lae Park, Wan Shik Ha
Journal of Korean Fiber Society 1982, 19 (3),
201-207.
June 1, 1982
*Domestic Journal Article