• Fibers and Polymers
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• 제7권3호
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• pp.229-234
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• 2006

Poly(vinyl acetate) (PVAc)/poly(vinyl alcohol) (PVA)/montmorillonite (MMT) clay nanocomposite microspheres with a core/shell structure have been developed via a suspension polymerization approach. In order to prepare the PVAc/ MMT and PVAc/PVA/MMT nanocomposite microspheres, which are promising precursor of PVA/MMT nanocomposite microspheres, suspension polymerization of vinyl acetate with organophilic MMT and heterogeneous saponification were conducted. A quaternary ammonium salt, cetyltrimethylammonium bromide, was mixed with the MMT in the monomer phase prior to the suspension polymerization. The rate of conversion decreased with an increase in MMT concentration. The incorporation of MMT into the PVAc was verified by FT-IR spectroscopy. Organic vinyl acetate monomers were intercalated into the interlayer regions of organophilic clay hosts and followed by suspension polymerization. Partially saponified PVA/MMT nanocomposite microspheres with a core/shell structure were successfully prepared by heterogeneous saponification.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.46-48
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• 2003

Poly(vinyl alcohol) (PVA) obtained from PVPi has the highest syndiotacticity among (PVA)s obtained via radical polymerization, and the s-diad content of PVA prepared by low temperature polymerization of vinyl pivalate (VPi)[1-5] comes to eve. 60%, Therefore, we an obtain (PVA)s with various tacticities through the copolymerization of vinyl acetate (VAc) and VPi and can examine the relation between physical properties of (PVA)s and their tacticities. (omitted)

• 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.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2000년도 봄 한국섬유공학회 학술발표회 논문집(Proceedings of the Korean Textile Conference)
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• pp.5-8
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• 2000

• 한국인쇄학회지
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• 제11권1호
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• pp.31-43
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• 1993

• 폴리머
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• 제32권2호
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• pp.95-102
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• 2008

The $\alpha$,$omega$-diacrylate poly(dimethylsiloxane) (DA-PDMS) containing vinyl ester of versatic acid/vinyl acetate (Veova-10/VAc) was prepared by emulsion copolymerization of (DA-PDMS), Veova-10 (with VAc), and auxiliary agents at $85^{\circ}C$ in the presence of ammonium peroxodisulfate (APS) as an initiator. Sodium dodecyl sulfate (SDS) and nonylphenol ethylene oxide-40 units (NP-40) were used as anionic and nonionic emulsifiers, respectively. The resulting copolymers were characterized by using Fourier transform infrared spectroscopy (FT-IR). Thermal properties of the copolymers were studied by using thermogravimetric analysis(TGA) and differential scanning calorimetry (DSC). The morphology of copolymers was also investigated by scanning electron microscopy (SEM) and then the effects of variables such as temperature, agitation speed, surfactant kinds, molecular weights, initiator, and DA-PDMS concentrations on the properties of the silicone-containing Veova-10/VAc emulsions were examined. The calculation of monomer conversion versus time histories indicates that by increasing the DA-PDMS concentration the polymerization rate and the number of polymer particles decrease, respectively.

• 접착 및 계면
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• 제12권1호
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• pp.1-10
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• 2011

자동화된 반응 열량계를 이용하여 중합비율을 관찰하면서 blockiness가 다른 PVOH를 이용하여 VAE 에멀젼을 합성하였다. 입자 분포도를 관찰 결과 단량체와 물과 비율에 따른 일정한 그라프트율은 없었다. 초기 단량체-물의 비율이 낮은 곳에서 겔 효과가 관찰되었다. 또한 입자 분포는 넓고 이중 피크가 관찰되었다. 지속적으로 제한적으로 응징집되면서 입자성장이 이루어지는 것이 관찰되었다. 이것은 제한적인 응집현상과 사슬이 PVOH로 그라프팅되어 발생한 결과로 판단된다.

• Elastomers and Composites
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• 제35권2호
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• pp.106-114
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• 2000

상온에서의 충격 흡수특성과 compression set 특성을 향상시키기 위하여 ethylene vinyl acetate copolymer (EVA)와 styrene vinyl isoprene styrene triblock copolymer (SVIS)를 블렌드하여 발포체를 제조하였다. 발포제 및 EVA/SVIS 블렌드비가 발포배율 및 기계적 물성에 미치는 영향을 조사하였다. SVIS 함량이 증가함에 따라 블렌드의 점도는 증가하였고 가교 속도는 감소하였으며, 발포배율은 감소하여 비중은 증가하였다. 발포제 함량 증가, 즉 발포배율 증가에 따른 반발탄성은 변화가 없는 반면에, SVIS 함량 증가에 따라 발포체의 상온에서의 tan ${\delta}$ 값은 증가하였으며 따라서 반발 탄성은 감소함을 알 수 있었다. EVA/SVIS 블렌드 발포체에서 SVIS 함량 증가에 따라 가교밀도와 비중이 증가하므로 compression set 값도 낮은 값을 나타내었다.

• 폴리머
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• 제24권5호
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• pp.579-588
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• 2000

보호콜로이드에 따른 입체 안정제 (steric stabilizer)작용이 폴리초산비닐 (poly(vinyl acetate), PVAc) 라텍스의 안정성에 미치는 영향을 조사하였다. 보호콜로이드로서 중합도 1080, 검화도 78.4%인 반응성 poly(vinyl alcohol) mono thiol (PVALT)를 사용한 것이 중합도 1100, 검화도 81.6%인 poly(vinyl alcohol) (PVA)를 사용하는 것보다 PVAc 라텍스의 안정성이 양호하였으며, 반응성 PVALT의 첨가량이 증가할수록 PVAc 라텍스의 안정성은 향상되었다. PVAc 라텍스 입자의 표면 형태 변화는 투과전자 현미경으로 관찰하였다. 입자크기는 반응성 PVALT의 첨가량이 증가할수록 감소하였다. 결과적으로 에멀젼의 중합 시 PVA보다 반응성 PVALT를 사용하는 것이 PVAc 라텍스의 안정성이 양호함을 알 수 있었다. 이는 반응성 PVALT로 인해 PVAc 라텍스 입자계면에 PVA와의 화학 결합을 유도할 수 있는 다량의 티올 (thiol)기가 도입되어 PVAc와 반응성 PVALT간의 화학반응으로 인한 PVALT-b-PVAc 블록 공중합체가 생성됨에 기인하는 것으로 사료된다. 아울러 제타전위는 탄산나트륨의 농도가 증가할수록 감소하였다.

• 한국안전학회지
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• 제25권3호
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• pp.61-65
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• 2010

Most of the chemical reactions performed in the chemical industry are exothermic, meaning that thermal energy is released during the reaction. It is also important to understand the thermal hazards such as thermal stabilities and runaway reactions, which are governed by thermodynamics and reaction kinetics of the mixed materials. The paper was described the evaluation of thermal behavior caused by an exothermic batch process in manufacture of the vinyl acetate resin. The aim of the study was to evaluate the thermal stabilities of raw materials with operating conditions such as a reaction inhibitor, heating rate, reaction atmosphere and the mount of methanol charged in the vinyl acetate polymerization process. The experiments were performed in the differential scanning calorimeter(DSC), C 80 calorimeter, and thermal screening unit($TS^u$). It was suggested that we should provide the thermal characteristics for raw materials to present safe precautions with operating conditions in the vinyl acetate polymerization process.