• Title/Summary/Keyword: photocrosslinking

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Octadecane Fixation via Photocrosslinking of Polyethylene Film (폴리에틸렌 필름의 광가교에 의한 옥타데칸의 고정화)

  • Yun, Deuk-Won;Jang, Jin-Ho
    • Textile Coloration and Finishing
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    • v.22 no.3
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    • pp.214-219
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    • 2010
  • Polyethylene(PE) films were photocrosslinked by continuous UV irradiation. Benzophenone addition as low as 1wt% into the PE film increased the gel fraction up to 96%. The photocrosslinking was attributed to the recombination of PE radicals generated upon UV irradiation, which was enhanced by the hydrogen abstraction of the added benzophenone. Also the crossliked PE showed higher thermal stability and decreased crystallinity with increasing UV energy as shown by TGA, XRD and DSC analysis. It was also possible to fix 5.4% octadecane into PE by the photocrosslinking. The crosslinked PE film containing octadecane showed lower tensile strength and modulus coupled with higher extension compared to that without octadecane, which can be used as a new plasticizing method for the crosslinked PE film.

Photopatternability of Poly(vinylcarbazole) Bearing Cinnamate Pendants and Its Blends with a Soluble Poly(p-phenylene vinylene) Derivative

  • Yu, Young-Jun;Lee, Seung-Hun;Choi, Dong-Hoon;Jin, Jung-Il;Tessler, Nir
    • Macromolecular Research
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    • v.15 no.2
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    • pp.142-146
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    • 2007
  • Poly[(1-(9-carbazoly1)ethylene)-co-(3-cinnamoyloxyoctyl-9-carbazolyl)] ethylene (PVK-Cin) was prepared by tethering cinnamate pendants to a carbazole group via an octylene spacer. The photopatternability of the new PVK based-polymer was investigated using a photocrosslinking reaction under UV light illumination $(\lambda=254nm)$. Blends of the PVK-Cin and a soluble poly(phenylene vinylene) (CzEh-PPV) were employed to study the photocrosslinking behavior. Well resolved lithographic patterns were observed in these polymer systems. PVK-Cin produced a blue light emitting pattern both before and after the photocrosslinking reaction. The blends of PVK-Cin and CzEh-PPV also showed corresponding emissions at 398 and 525 (560) nm in the film state.

Synthesis and Properties of Photocrosslinkable Polymers Containing Rosin Moiety (2) (로진을 함유하는 광경화성 고분자의 합성과 특성(2))

  • 김우식;류상철;홍기헌;이동호;민경은
    • Polymer(Korea)
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    • v.24 no.6
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    • pp.757-762
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    • 2000
  • Vinylbenzyloxystyrylpyridine (VSP) as a photosensitive monomer was synthesized by the reaction of 4-hydroxystyrylpyrydine with 4-vinylbenzyl chloride. Photocrosslinkable polymers containing rosin moiety were then prepared by radically copolymerizing VSP with a methacrylic monomer having rosin moiety. In these copolymerizations, the VSP feed ratios of 5 to 20 mol% were used. The contents of VSP units in the copolymers were determined by UV spectroscopy to be 5.3 to 17.3 mol%. The numberaverage molecular weights of these polymers were in the range of 18000 to 28000 and the polydispersity indexes were about 1.8. The glass transition temperatures were about 15$0^{\circ}C$ and the initial decomposition temperatures were about 34$0^{\circ}C$. The polymers were relatively fast photocrosslinked and the photocrosslinking reaction could be traced by the UV spectroscopy and the residual yield method.

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Photocrosslinking of Polyester by UV irradiation (자외선 조사에 의한 폴리에스터의 광가교)

  • Yun, Deuk-Won;Jang, Jin-Ho
    • Proceedings of the Korean Society of Dyers and Finishers Conference
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    • 2011.11a
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    • pp.7-7
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    • 2011
  • Poly(ethylene terephthalate)(PET) is one of the most widely used materials in textile industry. It can have a low cost, silk-like handle, and excellent mechanical properties. Low thermal stability of PET had been a common problem limiting its high temperature application. The polyester have been known to have the disadvantage of degradation under ionized irradiation compared to crosslikable polymers such as polyethylene, polypropylene and polystylene. To improve thermal stability of PET, the PET films were photocrosslinked by UV irradiation. A hydrogen-abstractable photoinitiator was used to photocrosslink of PET by continuous UV irradiation. Photoinitiator addition increased the gel fraction. The photocrosslinking was attributed to the recombination of PET radicals generated upon UV irradiation, which was enhanced by the hydrogen abstraction of the PET polymer chains by the added photoinitiator. Also the crosslinked PET showed higher thermal stability and mechanical strength with increasing UV energy. Polyester type films such as poly(ethylene naphthalate)(PEN) and poly(butylene terephthalte)(PBT) were also increased the gel fraction and improved thermal stability and mechanical properties by UV irradiation.

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The Improvement of Thermal Stability and Tensile Toughness by the Photocrosslinking of Poly(phenylene sulfide) containing Acetophenone (아세토페논을 함유한 Poly(phenylene sulfide)의 광가교에 의한 내열성과 인장인성 강화)

  • Jang, Yong-Joon;Jang, Jinho
    • Textile Coloration and Finishing
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    • v.24 no.4
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    • pp.281-287
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    • 2012
  • Poly(phenylene sulfide) films containing acetophenone as a photoinitiator were photocrosslinked under UV irradiation using a continuous UV irradiator. The gel fraction of the irradiated PPS in 1-Chloro naphthalene reached 94.7% with increasing UV energy and the photoinitiator concentration in the film upto $200J/cm^2$ and 12wt% respectively. Solid state $^1C$ NMR analysis suggested that the crosslinking occurred between the phenylene chains in PPS, indicating that the acetophenone may the phenylene hydrogens and subsequently adjacent polymer radicals could be recombined to form the crosslinked structure. The crosslinking improved the thermal behavior of PPS such as loss of $T_g$ and $T_c$, higher melting point and lower melting enthalphy as well as significantly higher peak pyrolysis temperature as much as $63.5^{\circ}C$. Surprisingly the tensile toughness of the most crosslinked PPS increased by 842%, resulting from the substantial enhancements in tensile modulus, strength and strain as much as 76%, 236% and 240% respectively. Also dynamic mechanical measurement indicated that the distance between crosslinks in the crosslinked PPS reached 85.3 g/mol corresponing to a crosslink density of 0.012 mol/g.

Photocrosslinking of PEO Films Using PEGDMA (PEGDMA를 이용한 PEO 필름의 광가교)

  • Gu, Gwang-Hoi;Jang, Jin-Ho
    • Proceedings of the Korean Society of Dyers and Finishers Conference
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    • 2008.10a
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    • pp.11-12
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    • 2008
  • Poly(ethylene oxide)(PEO) of molecular weight of 300,000 was crosslinked by UV irradiation in the presence of crosslinker. The photochemical crosslinking of PEO was enhanced by the addition of dimethacrylate crosslinkers in the film. Percent conversion of the polymer into gel as well as water absorbency were investigated gravimetrically. Gel fraction of PEO films increased with increasing crosslinker concentration. In the case of photocrosslinked PEO films with benzophenone, gel fraction reached about 95%. The thermal behavior of crosslinked PEO films was characterized by thermogravimetric analysis. The maximum decomposition temperature increased with increasing crosslinker concentration.

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Effect of Photopolymerization on the Rate of Photocrosslink in Chalcone-based Oligomeric Compounds

  • Choe, Dong Hun;O, Sang Jun;Ban, Si Yeong;O, Gwang Yong
    • Bulletin of the Korean Chemical Society
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    • v.22 no.11
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    • pp.1207-1212
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    • 2001
  • A new photochemically bifunctional epoxy and dimethacrylate compounds were synthesized for investigating the photosensitivity under UV irradiation. Photosensitivity of the synthesized chalcone-based compounds was investigated by using UV-visible absorption and Fourier transformed infrared (FT-IR) spectroscopies. The result of spectroscopic analysis substantiated that the two chalcone-based compounds have functions of both photocrosslinking and photopolymerization by UV exposure in the presence of photoinitiator. Two kinds of photochemical reactions proceeded competitively during UV exposure. Particularly, we studied the effect of photopolymerization on the rate of photocrosslink due to cycloaddition in the two oligomeric compounds.

Synthesis of Poly(cinnam-4'-yl methyl methacrylate) Derivatives and Their Thermal Stability as Photoalignment Layer

  • Lee, Jong U;Kim, Hak Won;Kim, Hong Du
    • Bulletin of the Korean Chemical Society
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    • v.22 no.2
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    • pp.179-182
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    • 2001
  • Photocyclizable poly(cinnam-4'-yl methyl methacrylate) derivatives bearing methoxy benzene (PMCMMA), anthracene (PACMMA), and coumarin (PCCMMA) have been synthesized via Heck type reaction. Three different types of polymers are photoreactable usin g linearly polarized UV light and applicable as liquid crystal alignment layer. Anthracence and coumarin containing polymers (PACMMA, PCCMMA) have better thermal stability than PMCMMA. This observation may be attributed to the glass transition temperature elevation due to the bulky size and another photocrosslinking site provided by anthracene or coumarin group.