• Polymer(Korea)
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• v.24 no.6
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• pp.837-844
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• 2000

The cure behavior of commercial epoxy molding compounds (EMC) commonly used for IC package was studied at constant cure temperatures as well as at constant heating rates using differential scanning calorimetry (DSC), rheometer, and dielectric analyzer (DEA). The cure kinetics were obtained using autocatalytic reaction model according to the Ryan Dutta method after assuming m+n equal to 2. The prediction of reaction rates by the model equation corresponded well to experimental data at all temperatures except for 10$0^{\circ}C$. The phase transitions such as gelation and vitrification occurred during network formation. At each isothermal cure temperature, $T_{g}$ was measured in accordance with cure time, and the vitrification point was attained when $T_{g}$ was equal to $T_{cure}$. The temperature dependence of gel points and vitrification points showed good agreement with Arrhenius relation. DEA using parallel plate electrode was effective for the monitoring of EMC cure. we knew that if the resin systems are materials of comparable quality, $_{gel}$$T_{g}$ is constant regardless of accelerator concentration in TTT (Time-Temperature-Transformation) diagram.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.6023-6028
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• 2013

Recently, biodegradable polymers are gaining more and more attention due to international environmental issues. Succinic acid is synthesised by chemical process of hydrogenation. Succinic acid synthesized has certain amount water content. To remove the water contained in succinic acid is used generally by hot air drying process. But recently, microwave drying process having the advantage of shortening the drying time and uniform drying of product are gaining more attention. In this study, hot air drying and microwave drying efficiency were compared at drying process. In addition, we confirmed commercial applicability in microwave drying process of succinic acid. Microwave drying process has higher efficiency than 70% compared with hot air drying process at thickness of 1cm. Economic efficiency were compared through examination of power consumption for complete drying of succinic acid at microwave and hot air dyring.

• Polymer(Korea)
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• v.25 no.2
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• pp.168-176
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• 2001

The effect of novel N-crotyl-N,N-dimethyl-4-methylanilinium hexafluoroantimonate (CMH) curing agent as a thermal latent initiator on thermal behaviors, rheological properties, and thermal stability of diglycidylether of bisphenol A (DGEBA) epoxy cationic system was investigated. From DSC measurements of DGEBA/CMH system, it was shown that this system exhibits an excellent thermal latent characteristic at a given temperature. The conversion and conversion rate of DGEBA/CMH system increased with increasing the concentration of initiator, due to high activity of CMH. Rheological properties of the system were investigated under isothermal condition using a rheometer The gelation time was obtained from the analysis of storage modulus (G'), loss modulus (G"), and damping factor (tan $\delta$). As a result, the reduction of gelation time was affected by high curing temperature and concentration of CMH, resulting in high degree of network formation in cationic polymerization, due to difference of activity. The thermal stability of the cured epoxy resin was discussed in terms of the activation energy for decomposition and thermal factors determined from TGA measurements.ents.

• Polymer(Korea)
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• v.26 no.1
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• pp.61-70
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• 2002

The effects of molecular weights and rheological properties of polypropylene (PP), on its foam structures in batch process were investigated. The effects of crosslinking process were also considered in this study. The rheological properties of polypropylene, such as storage modulus(G'), loss modulus(G"), zero shear viscosity($\eta_O$), and relaxation time($\lambda$), increased with the increase of molecular weights, and these increases in rheological properties directly affected the stability improvements of the PP foam. The increase of crosslinked PP's gel content stopped at the irradiation dose of 3.2 Mrad. The development of foam structures was more enhanced as the irradiation dose increased up to 3.2 Mrad. When the irradiation dose exceeded 3.2 Mrad, however, it negatively affected the structural development of the foam by diminishing gel contents of the foaming material, which resulted in instability of the foam structure.ture.

• Polymer(Korea)
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• v.26 no.1
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• pp.98-104
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• 2002

This study was investigated to fabricate the isotropic $Nd_2Fe_{14}B$/epoxy bonded magnets with high characteristics paroduced by compression molding. The magnetic characteristics of the bonded magnets were directly proportional to the density of the magnets and were enhanced by using raw $Nd_2Fe_{14}B$ magnetic powders, having the mean particle size of $200{\mu} m$.without additional milling process. The high characteristics of the bonded magnets were achieved at the following conditions: epoxy resin of 2.0 wt%, silane coupling agent of 0.8 wt%, curing agent of 0.7 wt% on the base of magnetic powders, and curing condition of $150^{\circ}C$/3 hrs. The bonded magnets at the optimum conditions indicated the high characteristics such as the density of 6.1 g/㎤, the remanent flux density of 7.1 kG, the maximum energy product of 9.7 MGOe, and the compressive strength of 17 kg/$mm^2$.

• Polymer(Korea)
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• v.28 no.6
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• pp.494-501
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• 2004

A new alkali developable photosensitive poly(amic acid) (PAA-0) with transmittance at 400 nm was synthesized from cyclobutane-1,2,3,4-tetracarboxylic dianhydride, 2-(methacryloyloxy)ethyl-3,5-diamino-benzoate and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyl disiloxane in N-methyl-2-pyrrolidinone. Photosensitivity of the PAA-0 was investigated at 365-400 nm in the presence of a photoinitiator using a high pressure mercury lamp. The photo-cured poly(amic acid) was insoluble toward aqueous 2.38 wt% tetramethylammonium hydroxide solution. Negative pattern of the PAA-0 with 25 ${\mu}{\textrm}{m}$ resolution was obtained by developing with 2.38 wt% tetramethylammonium hydroxide solution after exposure of 600 mJ/$\textrm{cm}^2$ in the presence of 2,2-dimethoxy-2-phenyl-acetophenone as a photoinitiator. The patterned poly(amic acid) was converted to polyimide by thermal curing at 25$0^{\circ}C$ for 50 min, which showed chemical resistance against photoresist stripper as well as good transmittance at 400 nm.

• Polymer(Korea)
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• v.26 no.1
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• pp.88-97
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• 2002

The effect of aminosiloxane modifier on the chemorheological properties of ortho-cresol novolac epoxy/phenol novelac/triphnylphosphine resin system was investigated aat different isothermal curing temperatures. By adding the aminosiloxane to the resin system, not only conversion rate and conversion were increased but also glass transition temperature was promoted. Critical conversion and gelation time obtained at the crossover point between storage and loss moduli were reduced and thus the viscosity was increased by the aminosiloxane. $C_1$ and $C_2$ in the WLF equation calculated from the glass transition temperature as a function of conversion and measured viscosity were found to vary with the curing temperature. By applying the change of glass transition temperature with conversion, $C_1$ and $C_2$ to WLF equation, it was possible to predict accurately the viscosity change with isothermal curing reaction.

• Polymer(Korea)
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• v.35 no.1
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• pp.1-6
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• 2011

Pressurized high temperature plastic resin flows into the cavity of mold and is solidified in injection molding process. Residual stress is being developed in injection molded part because of high temperature variations and high pressure. Developed residual stress relaxes as time goes. Consequently this makes part deformed and deteriorates quality of product. A measurement method of residual stress for injection molded transparent articles has been investigated using photoelasticity. Light, a composite of electromagnetic waves, is purified into a single wave by a polarized film. When this wave passes through the specimen, birefringence is developed according to the level of residual stress in the specimen and color fringed pattern appears after the second polarized film. Residual stress in the injection molded transparent flat a part has been measured quantitatively using the color fringed pattern. Optical characteristics have been a part also predicted by computer simulation and compared with experimental results.

• Polymer(Korea)
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• v.37 no.2
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• pp.249-253
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• 2013

From poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) synthesized using $CO_2$, a PLA/PPC/PLA layered film is prepared by coextrusion and then stretched to uniaxial orientation. The mechanical, optical, and barrier properties and shrinkage of the prepared film were investigated in detail. The maximum shrinkage of PLA/PPC/PLA film reached to 60% at $75^{\circ}C$. With increasing PPC content, the ratio of shrinkage of the film was increased and its shrinkagerate was increased. The ratio of shrinkage of the film decreased with increasing stretching temperature. The prepared film has oxygen and vapor transmission barrier properties. In this study, the PLA/PPC/PLA film is expected to be commercialized as a environmentally friendly shrinkable film.

• Elastomers and Composites
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• v.48 no.2
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• pp.125-132
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• 2013

In this work, we have discussed new engineering systems for preparing carbon master batch composed by carbon black and various organic compounds. In general, polymer resin, which applied for automobile tire, household items, and various industry items, is used with the fillers including carbon black and silica to control the color or properties. Domestic part and material industry has been remarkably developed in that the development of materials including the compounding of raw materials. Meanwhile, the engineering technique for mass production has not reached to a requirement of industry due to slow technique development and high dependence on foreign. Thus, we will focus on the introduction of new engineering technique developed by domestic company for preparing carbon master batch.