• Polymer(Korea)
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• v.37 no.4
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• pp.420-430
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• 2013

Polymer blends were prepared by solution blending poly(amic acid) (PAA) and poly(o-hydroxy amide) (PHA) having imide groups in the main chain. The polymers and their blends were characterized by using FTIR, FT NMR, DSC, TGA, SEM, XRD, UTM, and LOI. The solubility study revealed that the blends were readily soluble in aprotic solvents such as DMF, DMAc, DMSO, and NMP. The maximum weight loss of the blends occurred in the range of $578-645^{\circ}C$, and the maximum weight loss temperature increased with increasing the PHA content. The PBO/PI blends showed relatively high char yields (i.e. 56-69 wt%). The LOI values of the blends were in the range of 24.5-28.1% and increased with increasing the PHA content. The initial modulus and tensile strength of the blends increased by 57 to 121% and by 67 to 107%, respectively, compared to the values of PAA. Especially the initial modulus and tensile strength of the PHA/PAA=2/8(wt/wt) showed the highest values of 4.87 GPa and 108 MPa, respectively. The PHA domains of $0.03-0.1{\mu}m$ in their size were more or less uniformly dispersed. The interfacial adhesion between PAA and PHA was found to be good.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.6029-6038
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• 2013

In this study we attempt to modify the backbone structure and improve processibility of PBO having high melting and glass transition temperature. A series of aromatic poly(o-hydroxyamide)s(PHAs) were synthesized by direct polycondensaton of diacides containing diimide unit with two types of bis(o-aminophenol)s including 3,3'-dihydroxybenzidine and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. PHAs were studied by FT-IR, $^1H$-NMR, DSC and TGA. PHAs exhibited inherent viscosities in the range of 0.34~0.65 dL/g at $35^{\circ}C$ in DMAc solution. The PHA 1 and 6F-PHA 6, introducing o-phenylene unit in the main chain showed excellent solubilities in aprotic solvents such as NMP etc. However, the PHA 3, having p-phenylene unit was not even dissolved perfectly with LiCl salt. 6F-PHAs were readily soluble at room temperature in aprotic solvents except 6F-PHA 3. But they showed better solubility than that of PHAs. The polybenzoxazoles(PBOs) were quite insoluble in other solvents except partially soluble in sulfuric acid. PBOs exhibited relatively high glass transition temperatures(Tg) in the range of 306~$311^{\circ}C$ by DSC. The maximum weight loss temperature and char yields of PHA3 and 6F-PHA3 showed the highest values of $658^{\circ}C$ and $653^{\circ}C$, 62.6 % and 62.1 %, respectively.