• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.239-242
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• 2001

Melting and crystallization are not reversible because supercooling is always needed for crystal growth. But, recently reversible melting and crystallization phenomena in semi-crystalline polymers, based on modulated differential scanning calorimetry(MDSC) with quasi-isothermal experiment mode were observed in the melting range and continuously proved by others. (omitted)

• Bulletin of the Korean Chemical Society
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• v.25 no.12
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• pp.1941-1944
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• 2004

• Bulletin of the Korean Chemical Society
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• v.17 no.1
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• pp.11-15
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• 1996

A series of poly(1,4-phenylene terephthalates) with pendant NLO chromophores was prepared by the solution polycondensation of 2,5-NLO chromophore substituted terephthalic acid with hydroquinone. The polymers obtained gave satisfactory NMR and elemental analysis results when taking into account their expected structures and the inherent viscosity value proved the polymeric character of all polymers. DSC, optical polarizing microscopy and WAXS studies revealed that none of these polymers exhibited liquid crystalline mesophases. Preliminary results on NLO properties of these polymers showed a surprisingly large second harmonic signal relative to a Y-cut quartz plate.

• Clean Technology
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• v.8 no.4
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• pp.223-228
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• 2002

The biodegradable Properties of various polyester resins with different chemical structures have been studied by applying the controlled compost test and soil burial test. Celluose was taken as a fully biodegradable reference resin while PVC and PE were empolyed as non-biodegradable reference chains or ester group were rather easily degraded by hydrolase, meanwhile copolymer type polyesters which contain aromatic rings showed relatively low biodegradability. According to the results from controlled compost test, cellulose(the positive reference) showed 70.6% degradation after 45 days, whereas synthetic poly(butylene adipate-co-succinate), poly(butylene succinate), poly(butylene adipate-co-succinate-co-terephthalate) showed 44.0%, 32.0% and 23.4% degradation respectively. In this regard, it was concluded that biodegradable properties of polymers are largely dependant on the chemical structures constituting the polymers.

• Macromolecular Research
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• v.12 no.2
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• pp.195-205
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• 2004

We have synthesized new aromatic polyesters (DiPEG-HQ and DiPEG-BP) by condensation polymerization of a terephthalic acid derivative bearing a pendant oligo(oxyethylene) (DP = 7, MW = 350), which has a methoxy terminal group, and two different aromatic diols, hydroquinone and 4,4'-biphenoI. The synthesized polymers were characterized by differential scanning calorimetry (DSC), polarizing microscopy, and X-ray diffractometry for their liquid crystallinity (LC), thermal transitions, and structural morphologies in mesophases. The morphology of the LC phases depends strongly on the length of the rigid backbone repeating unit. The DiPEG-BP polymer having a longer repeating unit exhibits both layered and nematic structures before isotropization, whereas the DiPEG-HQ polymer having a shorter repeating unit shows only the layered structure in the mesophase. We found that the layer spacing for DiPEG-HQ is larger than that for DiPEG-BP. Both polymers easily form complexes with LiCF$_3$SO$_3$; we studied this complex formation by FT-IR spectroscopy. The layer spacing of the polymer-electrolyte composites increases upon increasing the amount of the lithium salt. The polymer/salt electrolyte mixtures we investigated at molar ratios of EO:salt in the range of 5-20 exhibit electrical conductivity values at 40$^{\circ}C$ of 2.4${\times}$10$\^$5/ and 1.1${\times}$10$\^$－5/ S/cm for DiPEG-HQ/LiCF$_3$SO$_3$ and DiPEG-BP/LiCF$_3$SO$_3$, respectively. At 80 $^{\circ}C$, these values are higher: 4.6${\times}$10$\^$－3/ and 1.1${\times}$10$\^$－4/ S/cm, respectively. The activation energy of conductivity depends strongly on the salt concentration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.4041-4046
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• 2010

Wholly aromatic polyesters having flexible alkoxy side chain were synthesized by direct polycondensation. The synthetic polymers have been characterized by $^1H$-NMR, FT-IR. DSC, TGA, optical polarizing microscope and X-ray diffractometer. The inherent viscosities (${\eta}_{inh}$) measured in 1,1,2,2-tetrachloroethane (TCE) were 0.46~2.41 dL/g. The polymers having side chain showed double melting transition, ie, solid-sanidic liquid crystalline (LC) phase transition ($T_{m1}$) and sanidic LC phase-nematic LC phase transition ($T_{m2}$). As incresing length of alkoxy side chain, phase transition temperatures decreased and solubilities in organic solvents incresed. The peaks of $2{\theta}\;{\simeq}5$ and $2{\theta}\;{\simeq}20$ in X-ray diffractograms are due to crystallization of polymer main chain and of long side chain, respectively.

• Journal of the Korean Applied Science and Technology
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• v.22 no.3
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• pp.270-280
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• 2005

To maximize a synergy effect in flame-retardancy of flame-retardant coatings, phosphorus and chlorine were introduced in polymer chains. Two-components PU flame-retardant modified polyesters (ABTTC-10C, -20C, -30C) were prepared by curing, at room temperature, of isocyanate (allophanate-trimer) and prepared modified polyesters which contain phosphorus and chlorine. To examine the film properties of the prepared flame-retardant coatings, film specimens were prepared with the prepared coatings. The film properties of ABTTC, ABTTC-10C and ABTTC-20C, which contain 0, 10 and 20wt%, 2,4-dichlorobenzoic acid (2,4-DCBA), respectively, were proved to be good, whereas the film properties of ABTTC-30C, which contains 30wt% 2,4-DCBA, were proved to be a little bit poor. Two kinds of flame retardancy tests, $45^{\circ}$Meckel burner method and LOI method, were performed. With the $45^{\circ}$Meckel burner method, three flame-retardant coatings except ABTTC showed less than 3.4 cm of char length, and showed less than 2 seconds of afterflaming and afterglow. From this result, the prepared flame-retardant coatings were proved to have the 1st grade flame retardancy. With the LOI method, the LOI values of the coatings containing more than 10wt% 2,4-DCBA were higher than 30wt%, which means that the coatings possess good flame-retardancy. From these results, it was found that synergistic effect in flame-retardancy was taken place by the introduced phosphorus and chlorine.

• Journal of the Korean Applied Science and Technology
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• v.23 no.1
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• pp.26-36
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• 2006

The aim of this study is to synthesis basic resins for the preparation of PU flame-retardant coatings that contain phosphorus and chlorine. After synthesizing intermediates of tetramethylene bis(orthophophate) (TMBO) and neohexanediol trichlorobenzoate (TBA-adduct), the condensation polymerization was performed with the intermediates, 1,4-butanediol, and adipic acid to obtain four-component copolymers. In the condensation polymerization, the content of phosphorus was fixed to be 2%, and the content of trichlorobenzoic acid (TBA) that provides chlorine component was varied to be 10, 20, and 30wt%, and we designated the prepared modified polyesters containing chlorine and phosphorus as TTBA-10C, TTBA-20C and TTBA-30C. Average molecular weight and polydispersity index of the prepared TTBAs decreased with increasing TBA content because of the increase in the number of hydroxyl groups that retards reaction. We found that the thermal stability of the prepared TTBAs increased with chlorine content at high temperatures.

• Journal of the Korean Applied Science and Technology
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• v.22 no.2
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• pp.123-135
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• 2005

Reaction intermediates PCP/BZA (PBI) and tetramethylene bis(orthophosphate)(TBOP) were synthesized from polycaprolactone (PCP) and benzoic acid (BZA) and from pyrophosphoric acid and 1,4-butanediol, respectively. Benzoic acid modified polyesters containing phosphorus (APTB-S, -10, -15) were synthesized by polycondensation of the prepared PBI (containing 5, 10, 15wt% of benzoic acid), TBOP, adipic acid, and 1,4-butanediol. Network structured PU flame-retardant coatings (APHD) were prepared by curing the synthesized benzoic acid modified polyesters containing phosphorus (APT B - 5 , -10, -15) with hexamethylene diisocyanate (HDI)-timer. From the TGA analysis of APTBs, it was found that the afterglow decreased with the amount of BZA content at the high temperatures. With the introduction of BZA, the film viscosity and film hardness of APHD decreased. With the introduction of caprolactone group, the flexibility, impact resistance, accelerated weathering resistance of APTBs increased. Flame retardancy of the coatings was tested. In a vertical burning method, APHD shows 210$^{\sim}$313 seconds, which indicates that the coatings are good flame-retardant coatings. Moreover, the amount of afterglow and flame retardancy of the coatings are decreased with increasing BZA content.

• Elastomers and Composites
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• v.48 no.4
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• pp.306-311
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• 2013

A series of liquid crystalline polyesters containing the 4-chloro benzoate group on the hydroquinone unit of rigid group were synthesized through solution polymerization of 2,5-di(4-chlorobenzoate)hydroquinones and 4,4'-dicarboxy-${\alpha},{\omega}$-diphenoxy alkane. The structure and properties for synthesized polymers were investigated by $^1H$-NMR, FT-IR, DSC, TGA, and POM. As result of investigations, The presence of the methylene group and bulky lateral groups in polymer chain have a great influence on the properties of polymers such as solubilities and thermal transitions. The optical textures of polymers revealed a weak birefringence in the melt and indicated that they form nematic mesophase. All polymers have very narrow mesophase temperature ranges.