• Polymer(Korea)
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• v.27 no.1
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• pp.33-39
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• 2003

In this study, the bisphenol-based DGEBA/GEBS blend systems were studied in cure kinetics, thermal stabilities, and fracture toughness of the casting specimen. The content of DGEBA/DCEBS was varied in 100 : 0, 90 : 10, 80 : 20, 70 : 30, and 60 : 40 wt%. The cure activation energies ($E_a$) of the blend systems were determined by Ozawa's equation. The thermal stabilities, including initial decomposed temperature (IDT), temperatures of maximum rate of degradation ($T_{max}$), and integral procedural decomposition temperature (IPDT) of the cured specimen were investigated by thermogravimetric analysis (TGA). For the mechanical interfacial properties of the specimens, the critical stress intensity factor ($K_{IC}$) test was performed and their fractured surfaces were examined by using a scanning electron microscope (SEM). As a result, $E_a$, IPDT, and $K_{IC}$ show maximum values in the 20 wt% DGEBS content compared with the neat DGEBA resins. This was probably due to the fact that the elevated networks were farmed by the introduction of sulfonyl groups of the DCEBS resin.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.16-21
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• 2006

In this study, PEO blend fibers mixed with polyaniline (PANI)/10-camphor sulfonic acid (CSA) and PANI/dodecylbenzene sulfonic acid (DBSA) were electro spun to investigate the influence of PANI content. CSA and DBSA were used as a functionalized doping acid having a bulky volume. PANI/PEO blend solution was prepared by dissolving PEO and PANI doped with CSA or DBSA. The thermal properties were measured by thermogravimetric analyzer (TGA). As a result, with increasing of the PANI content in PANI/CSA and PANI/DBSA, although initial decomposition temperature (IDT) was decreased, thermal stability was increased due to the increase of $A^*{\cdot}K^*$ and integral procedural decomposition temperature (IPDT). The electrical conductivities measured by the 4-probe method. The electric conductivity was increased with increasing of PANI content in PANI/CSA and PANI/DBSA. However, electrical conductivity did not change significantly beyond 30% content of PANI. From CV results, PANI/CSA showed the better defined peak shpae and higher peak current density compared to PANI/DBSA. This was probably related to the slightly higher electrical conductivity or better morphology for easy charge transfer in the case of PANI/CSA.

• Journal of Adhesion and Interface
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• v.5 no.1
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• pp.3-11
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• 2004

In this work, the cure behaviors of the DGEBA/PMR-15 blends initiated by N-benzylpyrazinium hexafluoroantimonate (BPH) as a cationic latent catalyst were performed in DSC and DMA analyses. And, the thermal stabilities were carried out by TGA analysis and their mechanical interfacial properties of blends were measured in the context of critical stress intensity factor ($K_{IC}$). As a result, the curing activation energy ($E_a$) determined from Ozawa's equation in DSC and the relaxation activation energy ($E_r$) from DMA were increased with increasing PMA-15 content. Also, the thermal stabilities obtained from the integral procedural decomposition temperature (IPDT) and the glass transition temperature ($T_g$) were highly improved with increasing the PMR-15 content, which were probably due to the high heat resistance. And, the $K_{IC}$ showed a similar behavior with $E_a$, which was attributed to the improving of the interfacial adhesion or hydrogen bondings between intermolecular chains.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.527-531
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• 2006

We have prepared organophilic inorganic particles and polyimide (PI) nanocomposite having excellent thermal stability and high dielectric constant that can be used for electronic application such as capacitor. We have chosen barium titanate (BT), a high dielectric constantmaterial and its surface was coated with nylon 6 to improve the affinity with PI. The FT-IR and TEM studies showed that the organophilic inorganic particle (BTN) has a polymer shell with thickness of 5 nm. We have suggested that it is possible to control the thickness of coating surface and also indicated the relationship between the ratio of inside and outside radius of BTN and the weight fraction of BT. The PI nanocomposite films based on poly(amic acid) and BTN were prepared by cyclodehydration reaction. The homogeneous dispersion of BTN in PI matrix was identified by using SEM. We have investigated the effect of BTN content on the coefficient of thermal stability, integral procedural decomposition temperature (IPDT), and dielectric constant of PI nanocomposite films.