• Elastomers and Composites
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• v.52 no.2
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• pp.143-153
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• 2017

Herein we studied the characterization of the PBO films formed via solution casting and thermal cyclization of poly(o-hyroxyamide)s(PHAs) that were synthesized by direct polycondensation of 3,3'-dihydroxybenzidine with 4,4'-(2,3-quinoxalinedioxy) dibenzoic acid and/or 4,4'-(2,3-pyridinedioxy) dibenzoic acid. All the PHAs exhibited inherent viscosities in the range of 0.55~0.84 dL/g in DMAc solution. The copolymers, CPH-2-5, were partially soluble in less polar solvents like pyridine and THF. However, all the PBOs were not soluble in polar solvents, but only partially soluble in sulfuric acid. The temperatures corresponding to 10% weight loss of the PBOs with increasing content of quinoxalinedioxy unit were higher than those of the PHAs, and the char yields at $900^{\circ}C$ in $N_2$, tensile strength, and initial modulus of the PBOs were 1.1~1.3 times, 1.2~1.8, and 1.6~3.3 times higher, respectively, than those of the PHAs. The LOI value of CPB-2 was 38.5%, while that of CPB-1 was the highest at 40.0%. The LOI test confirmed that excellent flame retardants were synthesized.

• 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.

• Elastomers and Composites
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• v.51 no.3
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• pp.195-205
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• 2016

A series of aromatic poly(hydroxyamide)s (PHAs) containing varying oligo(oxyethylene) substituents and 1,3-phenylene imide ring unit in the main chain were synthesized by the direct polycondensation reaction. The inherent viscosities of the PHAs exhibited in the range of 0.89~1.12 dL/g in DMAc or DMAc/LiCl solution. The PH-2~5 copolymers were easily soluble in strong aprotic solvents: DMAc, NMP, DMSO etc. and the PH-5 copolymer was soluble in less polar solvents such as m-creasol and pyridine with LiCl salt on heating. However, all PBOs were quite insoluble in other solvents, but only partially soluble in sulfuric acid. All copolymers (PH-2~5) could afford the flexible and tough films by solution casting. We identified that the PHAs were converted to the PBOs by the thermal cyclization reaction in the range of $200{\sim}380^{\circ}C$. The 10% weight loss temperatures and char yields of the PBOs were recorded in the range of $382{\sim}647^{\circ}C$ and 38.7~73.1% values at $900^{\circ}C$. The tensile strength and initial modulus of the PH-5 in the copolmers showed the highest values of 2.46 GPa and 49.55 MPa, respectively. The LOI values of the PHAs were in the range 26.6~29.0%, and increased with increasing 1,3-phenylene imide ring unit.