• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2001년도 가을 학술발표회 논문집
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• pp.187-190
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• 2001

The poly(vinyl alcohol) (PVA) fiber is recognized as the best candidate because of its good machanical properties together with excellent resistance to alkalis[1-5]. PVA cannot be prepared by the direct polymerization due to tautomerism of vinyl alcohol monomer. Thus PVA is obtained by the saponification of poly(vinyl ester) like poly(vinyl acetate) (PVAc). (omitted)

• Fibers and Polymers
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• 제5권4호
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• pp.253-258
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• 2004

Living nature of photoinduced cationic polymerization of isobutyl vinyl ether (IBVE) in the presence of various combinations of diphenyliodonium halide (DPIX), a photocationic initiator and zinc halide $(ZnX_2)$ in methylene chloride has been investigated. Attainment of $100\%$ conversion and a linear relationship between $\%$conversion and number average molar mass of the resulting polymer, strongly suggests the living nature of this system. Livingness of the polymerization system was observed irrespective to the type of halide anion of the initiator and zinc salts unless the reaction temperature is not higher than $-30^{\circ}C$. The rate of polymerization decreases in the order of iodide > bromide > chloride when halide salt of DPIX and $ZnX_2$ are used. It is postulated that the cationic initiation is started by the insertion of weakly basic monomer in to the activated C-X terminal of the monomer adduct which is a reaction product of monomer and HX, a photolytic product of DPIX, formed in situ during the photo-irradiation process. It was concluded that polymerization is initiated by the insertion of weakly basic monomer into activated C- X terminal of monomer adduct due to the pulling action of$ZnX_2$, which successively producing a new polarized C-X terminal for the propagation in cationic nature. This led us to a conclusion that the living nature of this cationic polymerization is ascribable to the polarized C-X growing terminal, which is stable enough to depress the processes of chain transfer or termination process.

• 청정기술
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• 제16권2호
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• pp.73-79
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• 2010

본 연구에서는 여러 가지 친환경적인 장점을 가지고 있는 초임계이산화탄소를 이용하여 비닐아세테이트 (vinyl acetate, VAc)를 분산중합하였다. 일반적인 유화중합에서보다 더 큰 분자량의 폴리비닐아세테이트(poly(vinyl acetate), PVAc)를 더 높은 수율로 생성시키고자 온도를 333.15 ~ 343.15 K, 압력을 20 ~ 40MPa, 개시제를 0.5 ~ 5%, 실리콘계 안정제를 1 ~ 10%, 반응시간을 2 ~ 50 시간으로 변화시켜 가면서 초임계이산화탄소 내에서 VAc를 반응시킨 후 생성되는 PVAc의 수율과 분자량 변화를 알아보았다. 그리고 최종 목표물인 폴리비닐알코올(poly(vinyl alcohol, PVA))를 PVAc로부터 합성하기 위해 비누화를 시키고 비누화 조건이 PVA의 분자량에 미치는 영향을 검토하였다.

• Fibers and Polymers
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• 제2권1호
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• pp.131-134
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• 2001

Living cationic polymerization behaviors of isobutyl vinyl ehters (IBVE), initiated by iodomethyl methyl ether (IMME)/zinc iodide ($Znl_2$) have been investigated. The polymerization was carried out at 0, -15, and $-30^{\circ}C$ in toluene. It was found that the rate of polymerization increased as the IMME concentration increased and decreased as temperature decreased. 100% conversion was always achieved without exception. Furthermore, the number-average molecular weight ($M_{n}$) of polymers increased in direct proportion to monomer conversion. The molecular weights of polymers were in good agreement with the theoretical values, calculated on the basis that one polymer chain was formed by one IMME molecule and the values of polydispersity index are always less than 1.2, revealing the living nature. The living nature was also confirmed by synthesis of poly(IBVE-b-TBVE) by subsequent monomer addition of t-butyl vinyl ether (TBVE).

• 대한화학회지
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• 제13권4호
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• pp.373-377
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• 1969

In order to determine the monomer reactivity ratio in copolymerization of acrolein, the copolymerization of acrolein with styrene, methyl methacrylate and vinyl acetate respectively was studied. The Q and e value of acrolein in each copolymerization were also calculated from those of monomer reactivity ratios, but the calculated values were slightly different from each other. The Q and e of acrolein for the system of acrolein-styrene copolymerization were Q = O.64 and e = O.62 respectively. Relations among the Q and e value, the composition and structure of copolymers and the mean sequence length in copolymerization were also discussed for acrolein copolymers.

• Fibers and Polymers
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• 제4권4호
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• pp.182-187
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• 2003

Low molecular weight copolymers of maleic anhydride and vinyl acetate were prepared to develop formaldehyde free cross-linking agents. Since lower molecular weight is favorable for efficient penetration of the finishing agent into the cotton fibers in the padding process, the concentration of the initiator, chain transfer agent and the monomer ratios were varied to obtain copolymers of low molecular weights. The prepared polymers were characterized by GPC, $^1{H-NMR}$, FTIR, DSC and TGA. Copolymers of molecular weights of 2 000 to 10 000 were obtained and it was found that the most efficient method of controlling the molecular weight was by varying the monomer ratios. Poly(maleic anhydride-co-vinyl acetate) did not dissolve in water, but the maleic anhydride residue hydrolyzed within a few minutes to form poly(maleic acid-co-vinyl acetate) and dissolved in water. However, the maleic acid units undergo dehydration to form anhydride groups on heating above ${160}^{\circ}C$ to some extent even in the absence of catalysts. The possibility of using the copolymers as durable press finishing agent for cotton fabric was investigated. Lower molecular weight poly(maleic anhydride-co-vinyl acetate) copolymers were more efficient in introducing crease resistance, which appears to be due to the more efficient penetration of the cross-linking agent into cotton fabrics. The wrinkle recovery angles of cotton fabrics treated with poly(maleic anhydride-co-vinyl acetate) copolymers were slightly lower than those treated with DMDHEU and were higher when higher curing temperatures or higher concentrations of copolymer were used, and when catalyst, $NaH_2$$PO_2$, was added. The strength retention of the poly(maleic anhydride-co-vinyl acetate) treated cotton fabrics was excellent.

• Nuclear Engineering and Technology
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• 제4권1호
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• pp.23-30
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• 1972

감마선 중합에 의한 목재와 프라스틱의 복합체 제조에 있어서, 각종 목재들에 대한 단량체의 침투량과 침투속도를 검토하였으며, 중합에 있어서는 국산 목재를 주로 하여 이에 각종 단량체 및 그 혼합물, 방사선의 조사량, 조사율, 이에 따르는 중합속도 등을 검토하여 다음과 같은 결과를 얻었다. 1) 단량체 침투에 있어서, 침투속도나 침투량은 모두 포플라에서 컸다. 2) 목재내에서의 단량체의 중합속도는 비닐 아세테이트-메찔메타아크릴레이트-스타이렌의 순서이며 필요한 전 조사량은 조사율 4$\times$$10^4$rad/hr에서 3~15Mrad의 범위었다. 따라서 중합속도의 관점에서 볼때 비닐아세테이트나 메찔메타아크릴레이트가 좋은 단량체 이다. 3) 단량체와의 결합에 있어서 리기다송, 육송등이 중합속도로 보아 효과적인 목재이다. 4) 목재 내부에서 단량체는 비교적 낮은 조사율인 2.1$\times$$10^4$rad/hr에서 더 용이하게 중합되었다.

• 청정기술
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• 제11권3호
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• pp.117-122
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• 2005

N-vinyl caprolactam (NVCL)은 초임계 분산 중합에 사용될 수 있는 비닐 아마이드 계열의 단량체이다. 이때 NVCL을 초임계 이산화탄소 상에서 분산 중합하기 위해서는 중합 초기 단계에 단량체가 $CO_2$에 모두 용해되어야 한다. 또한 최종 고분자로부터 미반응 단량체를 제거하기 위해서 중합 용매인 $CO_2$와 단량체 NVCL의 상거동 자료가 필수적이다. 하지만 단량체의 순수 물성은 측정 시 중합의 가능성이 있기 때문에 실험적인 제약이 있다. 본 연구에서는 이러한 단량체인 NVCL과 이와 유사한 작용기를 갖고 있는 N-methyl caprolactam (NMCL)의 순수 물성을 보다 정확하게 얻기 위하여 기존에 알려져 있는 그룹기여 방법을 수정하였다. 이때 유사한 구조를 갖는 ${\varepsilon}$-caprolactam을 바탕으로 새롭게 그룹 기여값을 얻고, 이를 NVCL, NMCL에 적용하였다. 또한 새롭게 수정된 순수 물성을 바탕으로 $CO_2$ + N-vinyl caprolactam과 N-methyl caprolactam 계에 대해 Peng-Robinson EOS와 van der Waals 1-fluid mixing rule을 이용하여 계산하고 실험값과 비교하였다.

• 한국염색가공학회지
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• 제5권3호
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• pp.194-205
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• 1993

Plasma polymerization in prepared glow discharge was carried out to improve the bathochromic of dyed PET fabrics by using silicon containing vinyl monomer in plasma polymerization equipment which consists of a pair of electrodes was connected to the 13.56MHz RF generator. The optimum condition for the bathochromic effect was investigated on various plasma polymeriztion parameters. By plasma polymerization used silicon containing vinyl monomer, the bathochromic of dyed PET fabrics was very enhanced. The optimum conditions on this equipment were as follows ; electrode distance : 3cm, discharge output : 60W, gas pressure : 0.3 Torr, monomer flow rate : 30㎤/min. plasma polymerization time : 60sec. The apparent strength of plasma polymerized PET fabrics was increased about 40∼47% with decreasing about 3 of L value.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.697-702
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• 2001

Numerical simulations of 1,2 dichloroethane(EDC) pyrolysis are conducted to understand the process on the production of the vinyl chloride monomer(VCM) and by-products. A chemical kinetic mechanism is developed, the adopted scheme involving 44 gas-phase species and 260 elementary forward and backward reactions. Detailed sensitivity analyses and the rates of production analysis are performed on each of the reactions and the various species, respectively. The concentrations of EDC, VCM, and HCI predicted by this mechanism are in good agreement with those deduced from experiments of commercial and laboratory scale. The mechanism is found to accurately predict the VCM yield and the production of by-products by varying the ranges of pyrolysis temperature, residence time, and pressure which impact on the pyrolysis of 1,2 dichloroethane. The influence of reactions related to H atom on the relative sensitivity of EDC becomes important as the residence time increases. The pyrolysis of EDC mainly occurs through $C_{2}H_{4}Cl_{2}+Cl=CH_{2}ClCHCl$.