• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.367-371
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• 2007

Nanocomposites prepared by PP(Polypropylene) based compatibilizers modified with GMA(Glycidyl methacrylate) and HEMA(Hydroxyethyl methacrylate) were used to investigate the clay dispersion and mechanical properties of them. XRD patterns showed the improvement of dispersion through clay intercalation according to the compatibilizers and comonomer. GMA modified polypropylene gave the best mechanical properties of the nanocomposite with respect to the balance of Flexural modulus (FM) and Notched izod impact strength(IS). Compatibilizers with comonoer commonly have higher grafting yield and lower melt flow rate than those of comonomer free. And they enhanced the clay dispersion and mechanical properties of nanocomposites. Optimum ratio of monomer to comonomer for nanocomposites having better mechanical properties is about 1 to 1 ratio.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.623-632
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• 1996

The reactivity ratios, melting temperature and polymer morphology in propylene/butene-1 and propylene/hexene-1 copolymerization reactions were studied by examining comonomer compositions of resulting polymers. The catalysts used here are different in their supports which are silica(catalyst I) and magnesium(catalyst II). As the content of comonomer(butene-1 and hexene-1) increased in the copolymer, the melting temperature of the copolymer decreased. The morphology of polymer was amorphous in the range of comonomer(butene-1) composition over 40% in the propylene/butene-1 copolymerization and comonomer(hexene-1) composition over 80% in the propylene/hexene-1 copolymerization. The reactivity ratios were obtained by the Fineman-Ross and Kelen-$T{\ddot{u}}d{\tilde{o}}s$ methods.

• Macromolecular Research
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• v.11 no.6
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• pp.425-430
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• 2003

Two types of poly(n-butyl acrylate) copolymer/silicate nanocomposites have been produced: poly(n-butyl acrylate-co-methyl methacrylate) [P(BA-co-MMA)]/silicate nanocomposites and poly(n-butyl acrylate-co-styrene) [P(BA-co-ST)]/silicate nanocomposites. The P(BA-co-MMA)/silicate nanocomposites shows the exfoliated structures but a P(BA-co-ST)/silicate nanocomposites have intercalated structures, because the BA/MMA comonomer has a higher polarity (e-value in Q-e scheme) than the BA/ST comonomer. The BA/MMA comonomer expanded the interlayer space of the silicate wider than did the BA/ST comonomer. The thermal degradation onset point of the P(BA-co-MMA)/silicate nanocomposites was 43$^{\circ}C$ higher than that of pure P(BA-co-MMA). P(BA-co-MMA)T5%, P(BA-co-MMA)T10%, and P(BA-co-MMA)T20% exhibit 134,302, and 195% increases, respectively, in their storage moduli at -20$^{\circ}C$ relative to the pure copolymer.

• Polymer(Korea)
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• v.31 no.5
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• pp.369-373
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• 2007

In this study, solvent-free pressure sensitive adhesives (PSA) using acrylic copolymer was prepared by UV radiation to investigate the effect of comonomer on the adhesion properties. Adhesive force value of PSA was increased with the amount of comonomer having shorter side chain due to the enhanced intrinsic surface energy. Peel and shear strength were also influenced by chemical properties of comonomer. The addition of comonomer, ethyl and n-butyl acrylate allows PSA sample with high peel and shear strength. This nay be explained in terms of correlation between loss modulus and glass transition temperature of PSA. As the addition of acrylic comonomers with long side chain length decreases the loss modulus of PSA, the deformation of PSA can not be inhibited.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.673-679
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• 2011

Bimodal high-density polyethylenes with different comonomer type and content were synthesized by polymerization of ethylene using Ziegler-Natta catalyst. Their structure and properties were studied using GPC, NMR, DSC and tensile test. It was found that ethylene/1-hexene copolymer exhibits higher tensile strength and elongation at break than that of ethylene/1-butylene copolymer with similar comonomer content. The molecular weight decreases as the comonomer content of the polymer increases. Short chain branching affects the crystallinity and thus the morphology and consequently the mechanical properties of the corresponding bimodal high-density polyethylenes. After SSA treated, the multiple endothermic peaks were observed. Multiple endothermic peaks are mainly attributed to the heterogeneity of ethylene sequence length and lamellar thickness. The difference of broadness index indicates that SCB distribution of polyethylene containing higher comonomer content has improved uniformity.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.50.1-50
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• 2001

Dynamic optimization with partially structured model in a slurry-phase HDPE reactor is implemented by the modified hierarchical dynamic optimization. Optimal trajectories of MI and density of HDPE are calculated as controlled variables and optimal profiles of the concentrations of ethylene, hydrogen and comonomer are calculated as manipulated variables in dynamic optimization. MI, density, the concentrations of ethylene, hydrogen and comonomer are used as controlled variables and flow rates of ethylene, hydrogen and comonomer are sued as manipulated variables in control implementation. Two-level hierarchical method is applied in dynamic optimization to reduce computation time. In the upper level formulation ...

• Macromolecular Research
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• v.17 no.6
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• pp.397-402
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• 2009

In emulsifier-free, emulsion polymerization with ionizable comonomer, the ionization of the comonomer is critical in determining the size of the final polymerie particles at sub-micrometer scale. In this study, polystyrene latex beads with carboxylates on the surface were synthesized using acrylic acid as a comonomer. Specifically, ammonium hydroxide was added to the emulsifier-free polymerization system to promote the ionization of acrylic acid by increasing pH. Smaller polystyrene latex particles were produced by increasing the ammonium hydroxide concentration in the reaction system, due to the enhanced stability promoted by the ionization of acrylic acid during the nucleation step. In addition, the surface morphology of the polystyrene latex particles was controlled by the concentration of acrylic acid, the dissociation of which was influenced by the ammonium hydroxide concentration.

• Journal of the Korean Wood Science and Technology
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• v.25 no.3
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• pp.75-82
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• 1997

To improve the quality of coated paper, the continuous research to the coating components and development of alternative latices is required. Recently, amphoteric latex is getting a great concern due to their changable properties of surface charge through controlling pH and some methods have been tried to prepare amphoteric latices. This study was carried out to synthesize amphoteric latex using seeding polymerization method with low concentration emulsifier. Styrene was used as a main monomer in addition to acrylonitrile for a hydrophilic comonomer. acrylic acid for a anionic comonomer and N,N-dimethylaminoethyl methacrylate for a cationic comonomer. Particle size and viscosity of latex were greatly affected by addition of acrylic acid and ammonium persulfate as an initiator. Negative charge of latex in alkali condition was changed to zero to positive charge in around pH 4.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.493-499
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• 2009

The properties of polystyrene and styrenic copolymer nanocomposites containing carbon nanotubes (CNT) and nanoclays were studied. Polystyrene and styrenic copolymer containing styrene and vinylbenzyl trimethylammonium chloride (SVTAC) were synthesized by emulsion polymerization. Polystyrene/CNT/clay and SVTAC/CNT/clay nanocomposites with various concentrations of CNT and different types of clay were prepared via mixing of polystyrene emulsion and clay. SVTAC/CNT nanocomposites showed a better electrical conductivity than PS/CNT nanocomposites. Nanocomposites with more surfactant during polymerization showed a better electrical conductivity than the ones with less surfactant. These indicated the positive effect of comonomer and surfactant on the electrical conductivity. Transmission electron microscopy (TEM) was used to analyze the state of CNT dispersion. TEM results showed that CNT loading, comonomer composition and amount of surfactant affected the final dispersion of CNT in nanocomposites. In order to confirm the effects of CNT loading, comonomer composition and the amount of surfactant on the thermal and dynamic mechanical properties, DSC and DMA analyses were conducted.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.516-521
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• 2007

The copolymerization characteristics of a newly-synthesized catalyst, $rac-Me_2Si(2-p-tolylindenyl)_2ZrCl_2$, and its analogue, $rac-Me_2Si(Ind)_2ZrCl_2$, were examined in the ethylene/1-octene copolymerization while varying the concentration of 1-octene in the reaction mixture. The activity of $rac-Me_2Si(2-p-tolylindenyl)_2ZrCl_2$ catalyst was decreased with increase of comonomer concentration, which is different from the usual comonomer effect of the metallocene catalysts with a bridge structure. The contents of 1-octene in the copolymer from the catalyst with 2-p-tolyl substituent were higher than those from the catalyst without that substituent. The melting point, crystallinity, and molecular weight decreased with comonomer content which was more apparent for $rac-Me_2Si(2-p-tolylindenyl)_2ZrCl_2$ catalyst.