• Title/Summary/Keyword: Polyhydroxyamides

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Synthesis and Cyclization of Aromatic Polyhydroxyamides Containing Trifluoromethyl Groups

  • Baik, Doo-Hyun;Kim, Hae-Young;Simon W. Kantor
    • Fibers and Polymers
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    • v.3 no.3
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    • pp.91-96
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    • 2002
  • Polyhydroxyamides derivatized with trifluorormethyl ether and trifluoromethyl ester groups were investigated as possible candidates for a new flame retardant polymer. Model compounds for these derivatized polyhydroxyamides were synthesized and their cyclization chemistry was investigated. The model compound study revealed that trifluorornethyl ester group containing model compounds can cyclize on heating, while trifluoromethyl ether group containing model compounds cannot. The non-fluorinated ether and ether derivatives behaved similarly. The trifluoromethyl ester derivatized polyhydroxyamides were synthesized according to the procedures for the model compounds. TGA characterization revealed that the fluorinated polymers have nearly same thermal stability as the underivatized PHA after cyclization.

Synthesis and Cyclization of Aromatic Polyhydroxyamides. 2. Polyhydroxyamides Containing Trifluoromethyl Group

  • Kim, Myung-Kyoon;Kim, Hae-Young;Baik, Doo-Hyun;Simon Kantor
    • Proceedings of the Korean Fiber Society Conference
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    • 1998.10a
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    • pp.41-44
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    • 1998
  • Wholly aromatic polybenzoxazoles (PBO) are well established as high performance materials with excellent thermal stability and mechanical properties. Heterocyclic precursor polymers such as polyhydroxyamides (PHA) have been interested in the field of high performance flame retardant polymers. The PHAs can be converted to PBOs when ignited. (omitted)

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Thermal Cyclization of Aromatic Polyhydroxyamides and its Derivatives(I) (폴리히드록시아미드와 그 치환체의 고리화 반응(I))

  • Kim, Eun-Kyoung;Kim, Myung-Kyoon;Baik, Doo-Hyun
    • Proceedings of the Korean Fiber Society Conference
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    • 2002.04a
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    • pp.347-350
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    • 2002
  • Wholly aromatic polybenzoxazoles(PBO) are well established as high performance materials with excellent thermal stability and mechanical properties. Heterocyclic precursor polymers such as polyhydroxyamides(PHA) have been interested in the field of high performance flame retardant polymers.[1] Precusor polymers have the advantages that they are easier to process, don't require strong solvents and can adsorb large amounts of heat energy during the cyclization process. (omitted)

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Synthesis and Cyclization of Aromatic Polyhydroxyamides. 1. Model Compound Study

  • Kim, Hae-Young;Kim, Myung-Kyoon;Baik, Doo-Hyun;Simon Kantor
    • Proceedings of the Korean Fiber Society Conference
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    • 1998.10a
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    • pp.37-40
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    • 1998
  • Aromatic polybenzoxazoles have been known since 1964 as a class of aromatic heterocyclic polymers that exhibit excellent thermal stability. Polyhydroxyamides (PHA), precursor polymers to PBO, can cyclize to farm stable heterocyclic polymers with the simultaneous release of small molecules, which can be expected to act as a fire quencher. (omitted)

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Synthesis and properties of PBO precursors having bulky groups and ether linkages in the main chain (주사슬에 벌키그룹과 에테르 연결고리를 갖는 PBO 전구체의 합성 및 특성)

  • Yoon, Doo-Soo;Kim, Hee-Sun;Choi, Jae-Kon;Hong, Wan-Hae
    • Elastomers and Composites
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    • v.43 no.4
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    • pp.271-280
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    • 2008
  • Aromatic polyhydroxyamides (PHAs) having bulky groups and ether linkages in the polymer main chain were synthesized by the low temperature solution polycondensation reaction. FT-IR, $^{1}H-NMR$, DSC, and TGA were used to study the properties of these polymers. The PHAs were converted into polybenzoxazoles (PBOs) by a thermal cyclization reaction, and endothermic peaks were observed in the range of $220{\sim}400^{\circ}C$. The introduction of the ether and bulky groups in the main chain improved the solubility of the PHAs in aprotic solvents such as DMSO and DMF, but the PBOs were nearly insoluble in common solvents. All the PBOs, except for PBO 5 with 2,6-dimethylphenoxy pendant and 2,3-dihydroxyquinoxaline ring, and PBO 6 with 2,6-dimethylphenoxy pendant and 2,3-dihydroxyquinoxaline ring, exhibited $T_g's$ in the range from 149 to $217^{\circ}C$ by DSC. The thermogravimetric analyses indicated that most of the PBOs were thermally stable up to $400^{\circ}C$ in nitrogen. Maximum weight loss temperatures of PHA 5 and PBO 5 with 2,6-dimethylphenoxy pendant and 2,3-dihydroxyquinoxaline ring were $707^{\circ}C$ and $683^{\circ}C$, respectively, which were the hightest temperatures among the corresponding copolymers. The PBOs in nitrogen exhibited relatively high char yields in the range of $63{\sim}70%$ at $900^{\circ}C$.

Synthesis and Thermal Properties of Aromatic Polyhydroxyamides Containing Imide Ring in the Main Chain (주 사슬에 이미드 고리를 갖는 방향족 polyhydroxyamides의 합성 및 열적 특성)

  • Wee, Doo-Young;Choi, Jae-Kon;Lee, Chang-Hoon
    • Elastomers and Composites
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    • v.46 no.4
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    • pp.295-303
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    • 2011
  • A series of new aromatic polyhydroxyamides (PHAs) containing imide ring were prepared by direct polycondensation reaction of imide-diacids and two types of bis(o-aminophenol)s including 3,3'-dihydroxybenzidine and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. The polymers were characterized by FT-IR, FT-NMR, DSC and TGA. The inherent viscosities of the PHAs measured at $35^{\circ}C$ in DMAC solution were in the range of 0.49-1.13 dL/g. PHA 2 and 3, except PHA 1, were soluble in polar solvents such as DMAc, DMF and NMP. PHA 4, 5, and 6 containing 6F group showed a higher solubility in less polar solvents. But the polybenzoxazoles (PBOs,) were insoluble in a variety of solvents except partially soluble in sulfuric acid. The PBO 1, 2 and 3 showed maximum weight loss temperature in the range of $650-656^{\circ}C$ and relatively high char yields in the range of 57.4-61.9 % under a nitrogen atmosphere. These results suggested that the introduction of imide or diimide ring in the main chain was effective in improving the thermal stability of PHAs and PBOs.

Preparation and Properties of Aromatic Polybenzoxazoles with high char yields (높은 char 수득률를 갖는 방향족 polybenzoxazoles의 제조 및 특성)

  • Sohn, Jun-Youn;Moon, Sung-Chul;Yoon, Doo-Soo;Choi, Jae-Kon
    • Elastomers and Composites
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    • v.42 no.4
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    • pp.238-248
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    • 2007
  • A series of polyhydroxyamides(PHAs) having ether linkages in the polymer backbone were prepared via solution polycondensation at low temperature. These polymers were studied by FT-IR, $^1H-NMR$, DSC, TGA and PCFC. The PHAs exhibited inherent viscosities in the range of $0.5{\sim}1.1dL/g\;at\;35^{\circ}C$ in DMAc solution. Most of PHAs except PHA 3 were soluble in polar organic solvents such as N,N-dimethylacetamide(DMAc), N-methyl-2-pyrrolidone(NMP), and N,N-dimethylform-amide(DMF). Subsequent thermal treatment of PHAs afforded polybenzoxazols(PBOs). However, the PBOs were insoluble in a variety of solvents. Most of the PBOs except PBO 3 showed glass-transition temperature($T_g$) in the range of $200{\sim}246^{\circ}C$ by DSC and maximum weight loss temperature in the range of $597{\sim}697^{\circ}C$ in nitrogen by TGA. PBOs showed high char yields in the range of $51{\sim}64%$. PCFC results of the PBOs showed the heat release(HR) capacity, $8{\sim}65J/gK$ and total heat release(total HR), $2.4{\sim}4.7kJ/g$.

Syntheses and Characterization of PBO Precursors Containing Dimethylphenoxy and/or MPEG Pendant Groups (Dimethylphenoxy와 MPEG 팬던트 그룹을 갖는 폴리벤즈옥사졸 전구체의 합성 및 특성)

  • Yoon Doo-Soo;Choi Jae-Kon;Jo Byung-Wook
    • Polymer(Korea)
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    • v.29 no.5
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    • pp.493-500
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    • 2005
  • Polyhydroxyamides(PHAs) having poly(ethylene glycol)methyl ether (MPEG) and/or dimethylphenoxy pendant groups were synthesized by solution polycondensation at low temperature. The inherent viscosities of the PHAs measured at $35^{\circ}C$ in DMAC or DMAc/LiCl solution were in the range of $0.51\~2.31dL/g$. This precursor polymers were studied by FT-IR, $1H-NMR$, DSC, and TGA. Solubility of the precursors with higher MPEG unit was increased, especially the polymer having MPEG $(M_n=1100)$ was soluble or partially soluble in ethanol, methanol, and water as well as aprotic solvents, but the PBOs were nearly insoluble in a variety of solvents. PHAs were converted to polybenzoxazoles (PBOs) by thermal cyclization reaction with heat of endotherm. In case of the precursors having MPEG nit, the precursor polymers with a higher $M_n$ were fully cyclized at a lower temperature than one with a lower $M_n$.

Physical Properties and Flame Retardency of Polyhydroxyamides (PHAs) Having Pendant Groups in the Main Chain (주사슬에 곁사슬기를 갖는 폴리히드록시아미드의 물성 및 난연특성)

  • Yoon, Doo-Soo;Choi, Jae-Kon;Jo, Byung-Wook
    • Polymer(Korea)
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    • v.30 no.6
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    • pp.478-485
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    • 2006
  • Physical properties and flammability of polyhydroxyamides (PHAs) haying poly (ethylene-glycol) methyl ether (MPEG) and/or dimethylphenoxy pendants were studied by using DSC, TGA, FTIR, pyrolysis combustion flow calorimeter (PCFC), and X-ray diffractometer. The degradation temperatures of the polymers were recorded in the ranges of $276{\sim}396^{\circ}C$ in air. PCFC results showed that the heat release (HR) capacity and total heat release (total HR) values of the PHAs were increased with in-creasing molecular weight of MPEG. In case of M-PHA 2 annealed at $290^{\circ}C$, the values of HR capacity were siginificantly decreased from 253 to 42 J/gK, and 60% weight loss temperatures increased from 408 to $856^{\circ}C$ with an annealing temperature. The activation energy for the decomposition reaction of the PHAs showed in the range of $129.3{\sim}235.1kJ/mol$, which increased with increasing conversion. Tensile modulus of PHAs were decreased as increasing chain of MPEG, and showed an increase more than initial modulus after converted to PBOs.

Preparation and Properties of PAA/PHA/Organoclay Nanocomposite (PAA/PHA/Organoclay 나노복합재료의 제조 및 특성)

  • Yoon, Doo-Soo;Choi, Jae-Kon;Jo, Byung-Wook
    • Polymer(Korea)
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    • v.34 no.4
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    • pp.326-332
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    • 2010
  • Nanocomposite films were prepared by blending poly(amic acid)(PAA), poly(o-hydroxyamide)( PHA) and organically modified montmorillonite (OMMT) that has a layered structure. XRD, SEM and TEM were used to study the morphology of PAA/PHA nanocomposites, and DMA, TGA, UTM, LOI and PCFC techniques were used to characterize the mechanical and thermal properties, and flame retardancy of the nanocomposites. TEM images revealed that OMMT layers were well dispersed in the PAA/PHA matrix and showed exfoliation and intercalation behavior. The addition of 3 wt% OMMT to the PAA/PHA blend increased the initial modulus of PAA/ PHA blend to 3.68 GPa that was ca. 48% higher than that of the control PAA/PHA blend. Above 4 wt%, however, both the initial modulus and the tensile strength were found to decrease, which might be due to the aggregation of OMMT in PAA/PHA matrix. When the OMMT content was below 3 wt%, the thermal stability and flame retardancy of the PAA/PHA nanocomposites increased with increasing OMMT content.