• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.71-75
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• 1998

Segmented block copolymer인 polyurethane은 열역학적으로 불친화성을 갖는 두 segment unit (Hard segment unit과 Soft segment unit)에 의해 미세 상분리 현상이 나타나며 그 결과 hard-segment-rich hard domain과 soft-segment-rich soft matrix 구조를 갖는다. 상온보다 높은 유리전이온도를 갖는 hard segment와 낮은 유리전이온도를 갖는 soft segment의 특성으로 인해 polyurethane은 열가소성 탄성체의 성질을 갖으며 두 성분의 조성비에 따라 넓은 범위의 역학적인 성질을 나타낸다.(중략)

• Macromolecular Research
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• v.10 no.6
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• pp.365-368
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• 2002

Thermoplastic polyurethanes (TPUs) with different hard segment length has been prepared from a fixed molar ratio of poly(tetramethylene ether glycol), 4,4'-diphenylmethane diisocyanate, and 1,4-butanediol by different polymerization procedures. Results reveal that the on-set temperature of endotherms ( $T_{cc}$ ) due to the crystallization of hard segments by cooling the TPUs from melt and the peak temperature of endotherms due to the melting of hard segments ( $T_{mh}$ ) by heating the TPUs increased and levelled off with increasing the hard segment length of TPUs. It has also been observed that soft segment glass transition temperature ( $T_{gs}$ ) of TPU decreased slightly with increasing the hard segment length, which explains less mixing of soft segments and hard segments. In tensile measurement of TPUs, strain hardening is observed with increasing the hard segment length, which is attributed to the strain induced crystallization of soft segments.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.466-469
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• 2002

Polyurethane(PU)은 segmented 블록공중합체로써 상온보다 높은 유리전이온도(glass transition temperature, Tg)를 갖는 hard segment(H.S)와 상온보다 낮은 Tg를 갖는 soft segment (S.S)로 구성되어 있다. 이들 두 segment간의 열역학적 불친화성으로 인해 미세 상분리 구조를 갖는다$^1$. 그 결과 hard segment-rich hard domain과 soft segment-rich soft matrix의 구조를 이룬다. 이중 hard domain(HD)은 상온에서 glassy한 성격을 띄므로 물리적 가교점과 충진제의 역할을 하며 soft domain(SD)은 rubbery한 성질을 가지므로 polurethane에 탄성을 부여하는 역할을 한다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.56-59
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• 2003

열가소성 폴리우레탄 탄성체는 유리전이온도가 낮은 soft segment와 융점이 높은 hard segment로 이루어진 블록공중합체이다. 이들 두 블록은 서로 상분리가 일어남으로써 각각 의 domain을 형성하며, 그 결과 hard segment는 가교의 역할을 행함으로써 우수한 탄성을 발휘할 수 있다. 이의 물성은 hard segment 및 soft segment의 조성과 화학구조 및 이들의 상분리 정도에 따라 다양하게 되며 또한 이의 전이온도도 다르게 변화시킬 수 있다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.350-351
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• 2003

Polyurethane은 물리적, 화학적 성질이 매우 다른 두 segment(hard/soft)로 이루어진 block copolymer로서 hard segment의 화학적 구조가 hard segment의 packing정도에 영향을 미쳐, PU의 미세상분리 현상을 결정하며 결과적으로 PU의 물리적 성질에 큰 영향을 미치게 된다$^1$. 본 연구에서는 hard segment의 packing을 향상시켜 PU은 열적 기계적 특성을 향상시키기 위하여 방향족환으로 구성되어 있어 aromatic diol의 일종인 hydroxyquinone-di-(beta-hydroxyl)ether(HQEE)를 chain extender로 사용하여 PU를 합성하였다. (중략)

• Polymer(Korea)
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• v.31 no.6
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• pp.543-549
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• 2007

We synthesized various polyurethanes(PU) haying different hard segments with different molecular weights of the soft segment to explore the effect of structure on the dispersion of silver particle in the phase of synthesized polyurethanes matrix. The thermal stability was increased by increasing the number of aromatic compound, while the degree of dispersion for silver particle was decreased. Silver particles showed better dispersion in the PU matrix having aromatic compounds when the soft segments were held constant. On the contrary, when the hard segment was held constant, silver particles on the PU matrix haying low $M_w$ of soft segment showed better dispersion than high $M_w$ of soft segment because poor chain mobility of low $M_w$ of soft segment restricted re-aggregation of silver particle. A sheet resistance of composite materials showed different aspects. In this case, the inter connection between silver particles was more important than its dispersion. In this study, the NDI-PEG 900/silver particle composite film showed the best thermal stability and electro conductivity.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.33-36
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• 1998

Segmented block copolyetheresters defined as copolymers having sequences of alternating polyester hard blocks and polyether soft blocks create labile physical cross-links upon crystallization of hard polyester blocks Since the nature of the physical interlocking is a crystallite formed exclusively from the crystallizable hard segment, the hard segment content (HSC) and hard segment length (HSL) will play an important role in determining the properties such as mechanical property and dynamic mechanical property. (omitted)

• Fibers and Polymers
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• v.7 no.4
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• pp.367-371
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• 2006

Thermal properties of copolyetherester/silica nanocomposites were examined by using DSC and TGA. The segmented block copolyetheresters with various hard segment structures and hard segment contents (HSC) were synthesized and their silica nanocomposite films were prepared by solution casting method. The nano-sized fumed silica particles were found to act as a nucleating agent of the copolyetheresters. The nanocomposites always showed reduced degree of supercooling or faster crystallization than the corresponding copolyetheresters. The nanocomposites also showed increased hard segment crystallinity except HSC 35 sample which had short hard segment length. In case of 2GT [poly(ethylene terephthalate)] copolyetheresters, which were not developed commercially because of their low crystallization rate, the hard segment crystallinity increased considerably. The copolyetherester/silica nanocomposites showed better thermal stability than copolyetheresters.

• Textile Coloration and Finishing
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• v.5 no.4
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• pp.60-66
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• 1993

Aqueous polyurethane(PU) anionomer dispersions were prepared from isophorone diisocyanate (IPDI), polytetramethylene adipate glycol(PTAd) and dimethylol propionic acid(DMPA) as potential anionic centers. The effects of polyol molecular weight(Mn) on the state of dispersion, thermal, mechanical, and viscoelastic properties and swelling of emulsion cast film were determined. With increasing Mn of PTAd, particle size of emulsion and soft segment T$_{g}$ decreased, and solvent swell, emulsion viscosity, and hard segment $T_{g}$ increased. Tensile strength showed minimum with PTAd 1000, and elongation at break generally increased with the Mn of PTAd. These results were possibly nterpreted in terms of soft segment-hard segment phase separation and crystallization of high molecular weight PTAd.

• Fibers and Polymers
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• v.4 no.3
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• pp.114-118
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• 2003

The prepolymer and the final polyurethane (PU) block copolymer were synthesized by reacting 4,4-methylene bis(phenylisocyanate) with poly(tetramethylene glycol) and the prepolymer with 1,4-butanediol as a chain extender, respectively, to investigate the relation between phase separation and it's resulting properties. According to FT-IR data, the phase separation of hard and soft segments in the prepolymer and the PU block copolymer grew bigger by increasing the hard segment content, and the PU showed more dominant phase separation than the prepolymer. The heat of fusion due to soft segments decreased in both the prepolymer and the PU by increasing the hard segment content, whereas the heat of fusion due to hard segments increased in the PU did not appear in the prepolymers. The breaking stress and modulus of the prepolymer increased by increasing the hard segment content, and the elongation at break decreased gradually, and the PU showed the highest breaking stress and modulus at 58% hard segment content. However, the best shape recovery of the PU was obtained at 47% hard segment content due to the existence of proper interaction among the hard segments for shape memory effect. Consequently, the mechanical properties and shape memory effect of the PU were influenced by the degree of phase separation, depending on the incorporation of chain extender as well as the hard segment content.