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요오드화 알킬 존재하의 비닐아세테이트의 조절된 라디칼중합
마석일,남혜인,한규찬,권순홍,Mah, Souk-Il,Nam, Hye-In,Han, Kyu-Chan,Kwon, Soon-hong 한국섬유공학회 2002 한국섬유공학회지 Vol.39 No.5
Radical polymerization behaviors of vinyl acetate (VAc), initiated by N, N-azobisisobuty-ronitrile(AIBN) in the presence of several alkyl iodides(RI) such as chloroiodomethane(CIM), iodoform, and tridecafluorohexyliodide(TDFHI) have been investigated. Living natu.e, i.e., a fairly good agreement between the number average degree of polymerization of the resulting polymer (DP$_{n}$) and the theoretical value, determined by the molar ratio of VAc and RI, which is based on the assumption that one polymer molecule is formed by one molecule of RI. A linear relationship is observed between % conversion and DP$_{n}$ is observed when the molar ratio of AIBN/RI is kept at 2. The MWD of the resulting polymer decreases as % conversion increases. Polymers having narrow molecular weight distrbution (DP$_{n}$DP$_{n}$ <1.5) are obtained in the late. stage of polymerization. However, experimental DP$_{n}$ values show deviation from the theoretical values in the early stage of polymerization. This leads us to the conclusion that the living nature of the system is ascribable to the stabilization of the active propagating radical species by rapid iodine exchange with RI followed by the establishment of equilibrium between the active propagating radical species and polymer having a dormant carbon-iodine terminal group. The factors resulting in the loss of the living nature have also been discussed in conjunction with the results obtained from photo-induced polymerization.erization.
디메틸페나실슬포늄 헥사풀루오로포스페이트 존재하의 에피클로로히드린의 광양이온 중합
마석일,선향,이강흡,Mah, Souk-Il,Seon, Hyang,Lee, Kang-Heup 한국섬유공학회 1993 한국섬유공학회지 Vol.30 No.7
Photocationic polymerization of epichlorohydrin in the presence of dimethylphenacylsulfonium hexafluorophosphate was carried out. Polymerization behaviors and the molecular structures of resulting polymer were discussed in relation to the reaction parameters such as the degree of dryness, initiator concentration, dark reaction time, temperature and duration of photoirradiation. The kinetic studies revealed that the % conversion to polymer during the photoirradiation is negligible and the polymerization mainly proceeds in the dark reaction period which implies the living nature of this polymerization system. However, the presence of initiator fragments at the end group of the polymer, confirmed by spectroscopic analysis indicated that the initiator takes a role not only in the initiation but also in the termination, which denies the true living nature of this polymerization system. A possible polymerization mechanism was proposed, based on the kinetic and spectroscopic results.
마석일,박우선,선향,이강흡,Mah, Souk-Il,Park, Woo-Yang,Seon, Hyang,Lee, Kang-Heup 한국섬유공학회 1992 한국섬유공학회지 Vol.29 No.4
Photopolymerization of a-methylstyrene in dichloromethane solution has been carried out in the presence of diphenyliodonium hexafluorophosphate A 500W high pressure mercury lamp was used as a light source of irradiation. The conversion of the monomer to polymer and the molecular weight distribution of the resulting polymer were measured by means of gravimetry and GPC, respectively. Higher rate of polymerization and higher average molecular weight of the polymer was observed at - 78˚C than those obtained at o˚C. Furthermore, bimodal molecular weight distribution of the polymer, obtained in the early stage of the reaction, revealed the simultaneous operation of the cationic species in the free ion and ion pair state.
열유도 상분리법에 의한 고밀도 폴리에틸렌 중공사막의 제조(IV) - 금속이온 흡착 한외 여과막 -
마석일,권순홍,선향,Mah, Souk-Il,Kwon, Soon-Hong,Sun, Hyang The Korean Fiber Society 1999 한국섬유공학회지 Vol.36 No.7
Hollow fiber membrane, containing amidoxime group has been prepared via AN grafting on to the plasma treated high density polyethylene(HDPE) membrane for ultrafiltration(UF), followed by amidoximation of the nitrile group of the grafted chain. It was found that cupric ion in the aqueous phase, is efficiently exhausted by the amidoximed membrane in water purification. This means that the modified UF hollow fiber membrane is very useful not only for the removal of microorganisms but also for the removal of the various metal ions from the aqueous phase. The effect of % graft on the water permeability of the membrane and the exhaustion of the metal ion dissolved in water under relatively low operating pressure of the water purification process was also discussed in relation to the morphological change of the membrane in various treatments.
폴리비닐리덴 플루오라이드를 다이큐밀펄옥사이드로 가교 시켰을 때의 가교 효과
설창,마석일,Seoul, Chang,Mah, Souk-Il The Korean Fiber Society 1994 한국섬유공학회지 Vol.31 No.3
The super-structure control for the piezoelectric polymer, poly(vinylidene fluoride) (PVFE). has been undertaken by many researchers to improve its piezoelectricity. But the preparation methods for the B-phase-rich samples were somewhat complicated. In this investigation, a new preparation method which involves crosslinking of PVF2 is suggested. PVF2 was dissolved in DHF with dicumylperoxide at 15$0^{\circ}C$ for 30min, and then a non-solvent was put into the polymer solution. In this way, PVF2 was crosslinked and crystallized at the same time. Using the simultaneous crosslinking/crystallization method, the PVF2 samples with B and Y characteristics could be produced. When 20% aqueous sulfuric acid solution was used as the non-solvent the pure B-phase PVF2 samples were obtained. When PVF2 was crystallized in the solutions, small amount of crosslinks played a positive role regarding the P-phase content. It is recommended that crystallinity reduction by crosslinks should be avoided to achieve the high piezoelectricity in the PVF2 tramples.