• Polymer(Korea)
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• v.24 no.5
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• pp.664-672
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• 2000

It is generally agreed that transesterification provides the, copolymer in the melt blending of poly(ethylene naphthalate) (PEN) and poly($\varepsilon$-caprolactone) (PCL). Effects of the conditions of transesterification reaction and catalyst on the degree of randomness and average sequence length of PEN/PCL blends were investigated and results were used to interpret the biodegradability of PEN/PCL blends. It was found that degree of randomness values of obtained copolymer lied between 0 and 1, and it indicated that this blend consisted with physical blends of PEN/PCL and PEN/PCL block copolymers. The degree of randomness reached almost 1 which is the theoretical value of random copolymers and the average sequence length became shorter by the further transesterification reaction. In additions, it was found that the increase of copolymers, especially random copolymers reduced the biodegradability in PEN/PCL blends.

• Polymer(Korea)
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• v.25 no.5
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• pp.699-706
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• 2001

The effects of uniaxial drawing conditions on the molecular orientation of poly (ethylene 2,6-naphthalate) (PEN) are investigated. Birefringence measurements show that the orientation is significantly enhanced at high draw ratio, low drawing temperature, and fast drawing speed. The characteristics of orientation examined by FTIR- ATR dichroism method represent almost same results. Amorphous orientation function increases with drawing rate at $120^{\circ}C$, but it decreases with drawing rate at $141^{\circ}C$. These behaviors can be explained with the relation between crystallization and chain relaxation rates. It is observed that the orientation of PEN film is accompanied by significant alignment of the naphthalene rings of PEN parallel to the film surface.

• Fibers and Polymers
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• v.4 no.4
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• pp.156-160
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• 2003

Poly(ethylene 2,6-naphthalate) (PEN)/Poly(ethylene glycol) (PEG) copolymers were synthesized by two step reaction during the melt copolymerization process. The first step was the esterification reaction of dimethyl-2,6-naphthalenedicarbox-ylate (2,6-NDC) and ethylene glycol (EG). The second step was the condensation polymerization of bishydroxyethylnaphthalate (BHEN) and PEG. The copolymers contained 10 mol% of PEG units with different molecular weights. Structures and thermal properties of the copolymers were studied by using $^1{H-NMR}$, DSC, TGA, etc. Especially, while the intrinsic viscosities of PEN/PEG copolymers increased with increasing molecular weights of PEG, but the glass transition temperature, the cold crystallization temperature, and the weight loss temperature of the copolymers decreased with increasing molecular weights of PEG. Consequently, the hydrophilicities by means of contact angle measurement and moisture content of the copolymer films were found to be significantly improved with increasing molecular weights of PEG.

• Journal of the Korean Applied Science and Technology
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• v.24 no.2
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• pp.167-173
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• 2007

The surface of poly(ethylene naphthalate) film applicable to high temerature insulator for convection microwave oven was modified with silicone coating solutions in the presence of silane crosslinking agent. The structure and properties of the PEN films were investigated by using Fourier transform IR spectroscopy, viscometry, microscopy, and tensile tests. The experimental results showed that the coating with silicone enhanced thermal stability up to $200^{\circ}C$, and slightly lowered the tensile strength and elongation of the PEN films. Judging from dimensional stability results the silicone coated PEN films can not be used for higher temperature insulator above $230^{\circ}C$. Serious dimensional contraction of films was obtained during heat treatment at $250^{\circ}C$ even for 1h. However, the surface of those films still have same chemical structure of silicones. Therefore, If we use PEN film prestretched at $230^{\circ}C$ as base one it will be possible to prepare a high temperature insulator up to $230^{\circ}C$. Conclusively, a silicone coated PEN film can be suitable for the application to convection microwave oven door insulator at high temperature up to $230^{\circ}C$.

• Polymer(Korea)
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• v.35 no.2
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• pp.146-151
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• 2011

The physical properties of poly (ethylene 2,6-naphthalate) (PEN) copolymers were studied. PEN copolymers were synthesized successfully from the mixtures of ethylene glycol(EG), 1,3-propanediol (PD) and l,4-butanediol (BD) with 2,6-dimethyl naphthalene dicarboxylate. The results indicated that PEN copolymers showed an amorphous state when the content of BD(PD) in applied EG/BD(EG/PD) mixtures was less than 40% during the polycondensation. As a result, the lowering of thermal properties, orientation, and mechanical properties was found, however, the dimensional stability was improved. This is a promising result to apply the synthesized PEN copolymers as flexibles substrates.

• Macromolecular Research
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• v.10 no.1
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• pp.44-48
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• 2002

The supermolecular structures of poly(ethylene terephthalate) (PET), poly(ethylene 2,6-naphthalate) (PEN), and their blend were investigated with optical microscopy and small angle light scattering. With increasing the crystallization temperature, incomplete spherulitic texture was developed for the PET samples. At a high crystallization temperature of 220 $^{\circ}C$, the light scattering pattern represented a random collection of uncorrelated lamellae. The general morphological appearances for the PEN samples were similar to that of the PET. A notable feature was that the spherulites of the PEN formed at 200 $^{\circ}C$ showed regular concentric bands arising from a regular twist in the radiating lamellae. The spherulitic morphology of the PET/PEN blend was largely influenced by the changes of the sequence distribution in polymer chains determined by the level of transesterifcation. The increased sequential irregularity in the polymer chains via transesterification caused a morphological transition from a regular folded crystallite to a tilted lamellar crystallite.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.70-73
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• 2003

최근 들어 poly(trimethylene terephtha)ate)(PTT)를 폴리에스터계 고분자들인 PET, PTN, PBN 등과 블렌드하고 이들의 특성 변화에 대해 검토한 결과가 많이 발표되고 있다. PTT를 PET나 PTN과 블렌드시키면 혼화성이 없으나, 이들 블렌드물을 용융시키면 점차 하나의 T$_{g}$를 나타내어 혼화성을 갖는다[1-3]. 반면에 PTT와 PBN을 블렌드시키면 처음부터 혼화성이 존재한다[4]. 이같이 PTT와 혼합되는 고분자의 종류에 따라 혼화성이 달라지는데, 본 연구는 PTT와 poly(ethylene naphthalate)(PEN)을 블렌드시키면 혼화성이 어떻게 되는가를 검토한 것이다. (중략)

• Polymer(Korea)
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• v.24 no.1
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• pp.113-123
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• 2000

Poly(p-hydroxybenzoate) (PHB)/poly(ethylene terephthalate) (PET) 8/2 thermotropic liquid crystalline copolyester, poly(ethylene 2,6-naphthalate) (PEN) and PET were mechanically blended to obtain the pseudo liquid crystalline (LC) phase of ternary blends. The torque values of blends with increasing PHB content were abruptly decreased above 40 wt% of PHB content, because the melt viscosity of ternary blends decreased. Tensile strength and initial modulus of blends containing above 30 wt% PHB were improved with increasing PHB content. Tensile strength and modulus of fiber were increased with PHB contents and take-up speed. Degree of transesterification and randomness of blends were increased with blending time. The blend of 40 wt% PHB was shown pseudo LC phase in the polarized optical photographs. Crystallinity of PHB/PEN/PET ternary blend were increased with PHB content.

• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.38-43
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• 1997

Poly(ethylene 2, 6-naphthalate-co-tetramethylene 2, 6-naphthalate) (PEN/PBN) copolymers were synthesized and studied by 13C NMR spectroscopy, DSC analysis and X-ray diffraction. A minimum in the melting point vs. composition curve was found at approximately 60 mol% tetramethylene 2, 6-naphthalate. The PEN/PBN copolymers were shown to be statistically random throughout the range of 1, 4-butanediol compositions. The melting point depression behavior of annealed PEN/PBN copolymers depended upon the sequence propagation probability, PS, which is suggested by indivisual crystal formation of two pure comonomers; that is, ethylene-naphthalate-ethylene, EE, and tetramethylene-naphthalate-tetramethylene, BB. However, it can be seen from the X-ray curve that the peaks of PEN/PBN copolymers appear from a crystal lattice which is governed only by the rich component between two different aliphatic units in the copolymer composition.

• Macromolecular Research
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• v.14 no.2
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• pp.146-154
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• 2006

Organic and inorganic hybrid nanocomposites based on poly(ethylene 2,6-naphthalate) (PEN) and silica nanoparticles were prepared by a melt blending process. In particular, polymer nanocomposites consisting mostly of cheap conventional polyesters with very small quantities of inorganic nanoparticles are of great interest from an industrial perspective. The crystallization behavior of PEN/silica hybrid nanocomposites depended significantly on silica content and crystallization temperature. The activation energy of crystallization for PEN/silica hybrid nanocomposites was decreased by incorporating a small quantity of silica nanoparticles. Double melting behavior was observed in PEN/silica hybrid nanocomposites, and the equilibrium melting temperature decreased with increasing silica content. The fold surface free energy of PEN/silica hybrid nanocomposites decreased with increasing silica content. The work of chain folding (q) for PEN was estimated as $7.28{\times}10^{-20}J$ per molecular chain fold, while the q values for the PEN/silica 0.9 hybrid nanocomposite was $3.71{\times}10^{-20}J$, implying that the incorporation of silica nanoparticles lowers the work required to fold the polymer chains.