• Polymer(Korea)
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• v.38 no.6
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• pp.714-719
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• 2014

Bio-based nylon 6-morpholinone random copolymers were prepared by the anionic ring opening polymerization of ${\varepsilon}$-caprolactam and morpholinone, both of which were prepared from lysine and glucose, respectively. From this work, a new biomass based nylon 6 with improved hydrophilicity was prepared. Optimizing the polymerization condition, copolymer with a viscosity-average molecular weight of 30000 g/mol was prepared, with a yield of 80%. It was possible to improve the hydrophilicity of nylon 6 by its copolymerization with morpholinone. The prepared nylon 6-morpholinone random copolymers were then characterized using several analytical methods such as DSC, TGA, XRD, viscosity measurement with U-shaped glass capillary viscometer and contact angle measurement.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.827-833
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• 2005

This study focused on the establishment of optimum formulation of polyamide based hot melt adhesive through adhesive synthesis, study of physical property, and adhesion study. In the previous study, the optimum formulation of base resins (CM831, 843P) and tackifying resin (terpene resin) was determined. The weight ratio of CM831, 843P, and terpene resin was 75, 25, and 10, respectively. Based on the optimum formulation, the effect of wax and filler addition was examined in this study. According to the results, the maximum adhesion strength with the steel could be obtained by the addition of 5 wt% of polyethylene wax although the melt viscosity of adhesive decreased continuously with the addition of wax. In the case of filler, the optimum adhesion property could be achieved by the addition of 10 wt% of talc. However, the addition of filler caused little increase of melt viscosity of adhesive.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.288-291
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• 2005

Resol type phenol-formaldehyde (PF) resin was synthesized by addition reaction of formaldehyde (F) and phenol (P). And the PF resin was synthesized by condensation reaction in which water was removed. In this work, we studied the influence of experimental parameters in the addition reaction, such as F/P mole ratio, amount of catalyst, reaction temperature, reaction time, and so on. Also, we studied the influence of molecular weight and viscosity of PE resin as a function of condensation time. As a result, in addition reaction, the reaction time decreased remarkably as the catalyst concentration increased, and the time decreased with increasing reaction temperature at a constant catalyst concentration. Also, in condensation reaction, the viscosity of resol type PF resin increased from 1500 to 9000 cps as a function of condensation time; molecular weight showed from 500 to 1100 g/mol.

• Polymer(Korea)
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• v.32 no.5
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• pp.409-414
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• 2008

The fabrication of gelatin nanofibers by electro spinning has been examined using the TFE/DW co-solvent system. It has been found that no beads-on-string structure was formed for the solution containing ionic salts. The resulting fibers exhibited a uniform diameter ranging from 110 to 125 nm. As the concentration of ionic salts increases, the beads become smaller and more spindle like, due to the increase of viscosity and conductivity. The addition of ionic salts induces a higher charge density on the surface of ejected jet during spinning, leading that higher elongation forces are applied to the jet. The higher enhancement of viscosity and conductivity was observed in gelatin solutions by the use of divalent salt. However, the concentration of ionic salts scarcely affected the variation of fiber diameter. While very low crystallinity was observed from XRD pattern for the sample containing no ionic salt, which increased with increasing the concentration of ionic salts.

• Polymer(Korea)
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• v.24 no.5
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• pp.646-655
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• 2000

Polymerizations of higher $\alpha$-olefins were carried out in toluene by using highly isospecific catalyst, rac-(EBI)M(NMe$_2$)$_2$ (EBI=1,2-ethylenebis-(1-indenyl); M=Zr(rac-1); M=Hf(rac-2)) In the presence of Al(i-Bu)$_3$/[Ph$_3$C][B($C_{6}F_{5}$)$_4$]. The polymerization of high $\alpha$-olefin showed high activity and similar polymerization behavior. The polymerization activity was affected by both monomer size and lateral size of polymer chain. The conversion of monomer to polymer decreases with the increased lateral size in the order of 1-pentene>1-hexene>1-octene>1-decene. The same dependences of melting behavior and intrinsic viscosity of polyolefin on lateral size were observed according to the results obtained by differential scanning calorimetry and intrinsic viscosity. All poly($\alpha$-olefin)s showed very high isotacticity (triad) and the isotacticity increases in the order of poly(1-pentene)$^1H$ NMR and Raman spectra analysis showed that chain transfer to cocatalyst, which generates saturated methyl groups, Is a main chain termination. The $\beta$-hydride eliminations, which generate unsaturated vinylidene, tri-substituted, and vinylene end group. are found to be minor chain terminations.

• Polymer(Korea)
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• v.30 no.6
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• pp.505-511
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• 2006

We tried to prepare polystyrene composite particles containing carbon black by suspension polymerization with water as a reaction medium. Hydrophobic silica was selected as a stabilizer and oil-soluble azobisisobutyronitrile (AIBN), as an initiator. All polymerization reactions were carried out at a fixed temperature of $75^{\circ}C$. Stabilizer concentration was varied from $0.17{\sim}3.33wt%$ compared to water, where particles with $7.96{\mu}m$ in average diameter were obtained at 1.57 wt% of stabilizer. Increase in divinylbenzene concentration, as a crosslinking agent, from $0.1{\sim}1.0 wt%$ compared to monomer exhibited a large increase in average particle diameter Incorporation of 1wt% of carbon black compared to monomer produced an increase in average diameter It is speculated that viscosity lower than that necessary to induce even dispersion of carbon black particles led to poor dispersion, and as a result, large particles. For a styrene mixture containing 3 wt% carton black compared to monomer, enhanced dispersion due to an increase in carbon black concentration reduced average particle diameters. For styrene mixtures containing 1 and 3 wt% carbon black compared to monomer, preparticles before polymerization and polymer composite particles after polymerization showed a similar tendency towards particle formation. When carbon black concentration compared to monomer was increased to 5 and 7 wt%, styrene mixtures exhibited a large increase in viscosity and thus better dispersion of carbon black particles, which led to a decrease in preparticle diameters. However, these particles experienced agglomeration in the polymerization process, and polystyrene composite particles increased in average diameter.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.58-63
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• 1999

Biodegradable films were prepared by solution blend method in the weight ratio of chitosan for the purpose of useful biomaterials. The possibility of biomaterials prepared from natural polymer as a skin substitute was evaluated by measuring biocompatibility. These films were inserts in the back of rat and their biodegradability was investigated by the film weight and hematology as a function of time for the biotransformation. The result of rat test showed that medium, high viscosity chitosan induced some suspects of inbiocompatibility in the tissue by goreign body reaction 48 and 72 hours after implantation. Also, we prepared the official burn ointment which is made by low viscosity chitosan. This burn ointment was covered on the skin wound of artificial burn and their effect of healing was investigated by the evaluation of the naked eye and hematological change as a function of time. The result of rats test showed that burn ointments made from chitosan was effective reductio of inflammation than negative group.

• Korea-Australia Rheology Journal
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• v.12 no.2
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• pp.107-117
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• 2000

Prediction of the product shape in sheet casting process is performed from the numerical simulation. A three-dimensional finite element method is used to investigate the flow behavior and to examine the effects of processing conditions on the sheet produced. Effects of inertia, gravity, surface tension and non-Newtonian viscosity on the thickness profile of the sheet are considered since the edge bead and the flow patterns in the chill roll region have great influence on the quality of the products. In the numerical simulation with free surface flows, the spine method is adopted to update the free surface, and the force-free boundary condition is imposed along the take-up plane to avoid severe singularity problems existing at the take-up plane. From the numerical results of steady isothermal flows of a generalized Newtonian fluid, it is shown that the draw ratio plays a major role in predicting the shape of the final sheet produced and the surface tension has considerable effect on the bead thickness ratio and the bead width fraction, while shear-thinning and/or tension-thickening viscosity affect the degree of neck-in.

• Elastomers and Composites
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• v.14 no.4
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• pp.231-252
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• 1979

Polymerization of 2-pyrrolidone was carried out through anionic mechanism using $SO_2/KOH$ as catalyst. The effects of KOH concentration, $SO_2/KOH$ mole ratio and temperature on polymerization were investigated. The conversion and viscosity of polymers were measured at various polymerization conditions. It was observed that as the concentration of KOH was increased, equilibrium conversion was also increased. It was, however, found that after the concentration of KOH was reached above 8 mole percent, the equilibrium conversion was decreased. The highest rate of polymerization and maximum conversion were obtained when $SO_2/KOH$ mole ratio was around 0.5. It was also found that the rate of polymerization and the equilibrium conversion were higher at $50^{\circ}C$. than at $30^{\circ}C$. but the viscosity of polymer solution at $50^{\circ}C$. was not so high as expected. The rate constant, $K_p$ of polymerization, was determined by least square method: the value of $K_p$ was observed as 16 liter/mole hour at $50^{\circ}C$. and 2.6 liter/mole hour at $30^{\circ}C$., respectively. The mechanism of polymerization was also discussed.

• Elastomers and Composites
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• v.23 no.2
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• pp.125-133
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• 1988

The thermal degradation of polymethyl methacrylate(PMMA) blend namely polymethyl methacrylate-polycarbonate(PMMA-PC) blend and polymethyl methacrylate-polystyrene(PMMA-PS) blend were carried out by isothermal method under air at several heating temperature from 220 to $270^{\circ}C$. Molecular weight changes during the thermal decomposition were monitored by means of the viscosity average molecular weight($\bar{M}v$). The viscosity average molecular weight was determined by Gel Permeation Chromatography(GPC). The dominant process in the degradation of PMMA-PC and PMMA-PS blend were main chain scission randomly due to weak links that may be distributed along the polymer backbone and the initial rate which the bonds are broken is not sustained. The infra-red spectra of degraded PMMA-PS blend show that the presence of aromatic ketone band at $1685cm^{-1}$. However, the infra-red spectra of degraded PMMA-PC blend show that the presence of hydroperoxide band at $3450cm^{-1}$. Thus indicating that the weak links are attacked by oxygen from the air and produce hydroperoxide or ketone. The activation energies of PMMA-PC blend and PMMA-PS blend were 18.2 and 17.9 Kcal/mol, respectively.