• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.144-150
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• 2013

The kinetics of the transesterification of dimethyl terephthalate (DMT) with ethylene glycol (EG) was studied in a batch reactor. Bishydroxyethyl terephthalate (BHET), which is poly(ethylene terephthalate) (PET) monomer, can be produced by the transesterification reaction. Zinc acetate was used as a catalyst. Previous kinetic studies was carried out in a semi-batch reactor where generated methanol was removed so that reverse reactions were not considered in the kinetic expressions, resulting in inaccuracy of the kinetic model. Mathematical models of a batch reactor for the tranesterification reaction were developed and used to characterize the reaction kinetics and the composition distribution of the reaction products. More accurate models than previous ones were obtained and found to have a good agreement between model predictions and experimental data. Effect of process variables on the esterification reaction was investigated based on the experimental and simulation results.

• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.58-67
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• 2013

PBT (polybutylene terephthalate) has excellent mechanical properties such as low absorption, dimensional stability, abrasion resistance. It is used in manufacturing electronic components, the automobile part and the various precise parts. Bis (hydroxybutyl) terephthalate (BHBT) which is a PBT monomer, can be produced by transesterification reaction of DMT (dimethyl terephthalate) with 1,4-butandiol (BD). The kinetics of transesterification reaction of DMT with BD using zinc acetate as a catalyst was studied in a batch reactor. Previous kinetic studies was carried out in a semibatch reactor where generated methanol was removed so that reverse reactions were not considered in the kinetic expressions, resulting in inaccuracy of the kinetic model. Mathematical models of a batch reactor for the transesterification reaction were developed and used to characterize the reaction kinetics and the composition distribution of the reaction products. More accurate models than previous models was obtained and found to have a good agreement between model predictions and experimental data.

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.253-261
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• 2015

The kinetics of the transesterification of dimethyl terephthalate (DMT) with diethylene glycol (DEG) was studied in a batch reactor. bis-hydroxyethoxytethyl-terephthalate (BHEET), which is polyester polyol monomer, can be produced by the transesterification reaction. Zinc acetate was used as a catalyst. Previous kinetic studies was carried out in a semi-batch reactor where generated methanol was removed so that reverse reactions were not considered in the kinetic expressions, resulting in inaccuracy of the kinetic model. Mathematical models of a batch reactor for the tranesterification reaction, which took the reverse reaction into account, were developed and used to characterize the reaction kinetics and the composition distribution of the reaction products. More accurate models than previous ones were obtained and found to have a good agreement between model predictions and experimental data. Effect of process variables on the esterification reaction was investigated based on the experimental and simulation results.

• Journal of the Korean Chemical Society
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• v.40 no.1
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• pp.87-95
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• 1996

The binary random copolyesters of poly(butylene succinate-co-butylene terephthalate) (PBS/PBT) were synthesized and their sequence distributions were investigated over the entire range for PBS/PBT copolyester compositions by 1H NMR spectroscopy. The melting point (Tm) of these copolyesters were depressed gradually with the increase of dimethyl terephthalate (DMT) mol% in composition and appeared an eutetic behaviour which appears a minimum at ST3 (DMT 65.8 mol%). The melting behaviour of PBS/PBT copolyester was not directly depended on molar fraction (Xa) but on only the sequence propagation probability (P) which occurs in triad fraction. It also can be seen that when the succinate units (or terephthalate units) were abundant enough, PBS/PBT Copolymers formed only PBS (or PBT) crystal with complete rejection of the terephthalate units (or succinate units).

• Polymer(Korea)
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• v.29 no.1
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• pp.41-47
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• 2005

The transesterification of dimethyl terephthalate (DMT) with 1,3-propanediol (PDO) was investigated in the presence of catalyst, titanium (IV) butoxide (TBO), at 175~190 $^{\circ}C$ . The degree of transesterification reaction was measured by the output of methanol which was distilled from the reactor. The amount of methanol increased as the reaction temperature, molar ratio and catalyst concentration increased. The observed overall rate of the transesterification was third order; first order with respect to DMT, PDO, and the concentration of catalyst, respectively. Using calculated rate constants, the activation energy for transesterification was 26.93 kcal/mole. The melting temperature of bis(2-hydroxytrimethyl) terephthalate (BHTMT) was 85.2$^{\circ}C$ and heat of fusion 141.3 J/g.

• Proceedings of the Korean Fiber Society Conference
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• 1994.04a
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• pp.111-112
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• 1994

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.351-354
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• 2001

Poly(ethylene terephthalate) (PET)는 물리적, 기계적 성질이 우수한 엔지니어링 플라스틱의 하나로 섬유, 필름, 및 여러 가지 용도로 다양하게 사용되고 있다. PET는 DMT(dimethyl terephthalate) 또는 TPA(terephthalic acid)와 EG(ethylene glycol)를 축합 중합하여 제조한다. (중략)

• Clean Technology
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• v.13 no.1 s.36
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• pp.46-53
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• 2007

We depolymerized PET in supercritical methanol and observed the yield of DMT at various reaction conditions. At subcritical state below $240^{\circ}C$, the yield of DMT was very low, about only 50%. It increased dramatically to 80% at supercritical state above $260^{\circ}C$, thereafter the increasing rate was reduced significantly. Similarly, at subcritical state of 6.89 MPa, the DMT yield was only 50%, but it increased abruptly to 85% at supercritical state of 10.34 MPa, yielding no further increase above the pressure. Within 10 minutes after the beginning of the reaction, the DMT yield reached 80%, indicating that the significant portion of the reaction has proceeded, and then, the yield increased slowly. The methanol/PET ratio of 8 showed the maximum DMT yield. We found the optimum depolymerization condition fur PET methanolysis is temperature $300^{\circ}C$, pressure 10.34 MPa, reaction time 40 minutes, and methanol/PET ratio of 8.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.294-298
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• 2017

Six new fluorescent whitening agent's candidates with 4,4'-di((E)-styryl)-1,1'-biphenyl skeleton which is the same as that of Uvitex FP family were synthesized using methyl 4-formylbenzoate (MFB) as a starting material. MFB has been disposed as a by-product of dimethyl terephthalate (DMT) production process. Six candidates were synthesized by the reaction of MFB, and its derivatives with tetraethyl biphenyl-4,4'-diylbis(methylene)diphosphonate (3) using Wittig-Horner reaction. A series of UV spectra were recorded and the results were used for estimating molar absorptivities of each candidates in order to find their potential application as fluorescent whitening agents. Considering the molar absorptivity (log ${\varepsilon}$ 3.95~2.60) for all candidates was lower than that of the commercial Uvitex FP 127 (log ${\varepsilon}$ 4.85), it was concluded that they are not suitable for fluorescent whitening agent applications.

• Elastomers and Composites
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• v.47 no.2
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• pp.96-103
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• 2012

This paper reviews recent technologies for recycling poly (ethylene terephthalate) wastes. Wide application and non-biodegradability of the PET creates huge amounts of waste and disposal, leading to an environmental problem and economic loss. Chemical recycling can be a promising technology to deal with these problems by converting the waste into useful feedstock material for polyester production. Chemical recycling of polyethylene terephthalate are processes where the PET polymer chain is destructed by the impact of glycol (MEG) causing glycolysis, methanol causing methanolysis or water causing hydrolysis. After intensive purification polyester oligomers or the monomers MEG, dimethyl telephthalate (DMT) or purified terephthalic acid (PTA) are received which are re-used to produce polyester products.