• Korea-Australia Rheology Journal
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• v.19 no.1
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• pp.7-16
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• 2007

A dynamic Monte Carlo percolation grid simulation is used to predict the cure behaviour of thermoset materials. Molecules are distributed in a fixed grid and a probability of reaction is assigned to each pair of neighbouring units considering both reaction rates and diffusion. The concentration and network characteristics are predicted throughout the whole curing process and compared to experimental data for an epoxy-amine matrix.

• Korea-Australia Rheology Journal
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• v.12 no.1
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• pp.77-81
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• 2000

Rheological behavior of thermoset/thermoplastic blends of epoxy/polyethersulphone (PES) was monitored during curing of the epoxy resin. During the isothermal curing of the mixture, a fluctuation in viscosity just before the abrupt viscosity increase was observed. This fluctuation is found to be due to the phase separation of PES from the matrix epoxy resin during the curing. The experimentally observed viscosity fluctuation is simulated with a simple two phase suspension model in terms of the increase in domain size. The viscosity profiles obtained experimentally at different isothermal curing temperatures are in good agreement with the predictions from the simple model taking into account the viscosity change due to the growth of PES domain and the network formation of the epoxy matrix.

• Polymer(Korea)
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• v.24 no.5
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• pp.690-700
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• 2000

In this study, an elastomer-assistered compression molding process was investigated by experiments as well as modeling for the long-fiber reinforced thermoset composites. The consolidation pressure generated by fixed-volume and variable-volume conditions was thermodynamically derived for both elastomer and curing prepregs, and was compared with the pressure measured during curing of epoxy matrix. Exhibiting non-linear viscoelastic characteristics in the compressive stress-strain tests, the measured stress was well compared with a modifed KWW (Kohlrausch-Williame-Watts) equation, which is based on the Maxwell viscoelastic model. Using the developed model equations, the consolidation pressure generated by the elastomer was successfully predicted for the compression molding process of thermoset composite materials in tile closed mold system.

• Transactions of Materials Processing
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• v.24 no.6
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• pp.418-425
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• 2015

Based on eco-friendly advantages and the enhanced development in the chemical and physical characteristics, liquid silicone rubber (LSR) is widely used in producing precision parts in the automotive, medical, electronics, aeronautical and many other industries. In the current work, a thermoplastic-thermoset multi component injection molding (MCM) was developed for a waterproof automotive connector housing using PBT and LSR resins. Measurements of the rheological characteristics of PBT and LSR were made to improve the reliability of the numerical analysis for the multi component injection process. With the measured viscosity, pvT and curing data, numerical analysis of the multi cycle injection molding was conducted using simulation software (Sigma V5.0).

• Journal of the Korean Applied Science and Technology
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• v.29 no.1
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• pp.159-173
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• 2012

UV-Curing technology can be classified into two categories for radical curing and cation curing. It also has mainly focused on surface finishing technology to improve functionality of various substrates such as plastics and metals. On the other hand, EB technology has dealt with cross-linking reactions as well as polymerization process to create novel functional materials. Both technologies have advantages in energy utilizing efficiency and environmental friendly when compared to conventional thermoset coatings. Consequently, UV cured coatings also permits a reduction in the $CO_2$ and VOCs emitted in the drying and curing process. This review mainly shows radical curing technology which is commonly used in UV curing coatings and also describes the technology trends of cation curing which has been attracted attention recently.

• Clean Technology
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• v.12 no.1
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• pp.27-35
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• 2006

Main compositions of powder paint based on thermoset type epoxy resin consist of epoxy resin for powder coating, curing agent, filler and pigment. The curing system used in this study was based on diglycidyl ether of bisphenol-A (DGEBA) and dicyan diamide (DICY). The curing behavior and rheological properties of powder coating material were investigated using DSC and rheometer, respectively. And the adhesion strength between steel and powder coating material was measured using lap shear geometry. The optimum formulation of epoxy powder paint obtained from this study was base resin of 100 phr, DICY of 6 phr, $CaCO_3$ of 20 phr, and $TiO_2$ of 10 phr.

• Journal of the Korean Wood Science and Technology
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• v.34 no.2
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• pp.37-45
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• 2006

The viscoelastic properties of blends of melamine-formaldehyde (MF) resin and poly(vinyl acetate) (PVAc) for engineered flooring used on the Korean traditional ONDOL house floor heating system were investigated by dynamic mechanical thermal analysis (DMTA). Because MF resin is a thermosetting adhesive, the effect of MF rein was shown across all thermal behaviors. The addition of PVAc reduced the curing temperature. The DMTA thermogram of MF resin showed that the storage modulus (E') increased as the temperature was further increased as a result of the cross-linking induced by the curing reaction of the resin. The storage modulus (E') of MF resin increased both as a function of increasing temperature and with increasing heating rate. From isothermal DMTA results, peak $T_{tan{\delta}}$ values, maximum value of loss modulus (E") and the rigidities (${\Delta}E$) of MF/PVAc blends at room temperature as a function of open time, peak $T_{tan{\delta}}$ and maximum loss modulus (E") values were found to increase with blend MF content. Moreover, the rigidities of the 70:30 and 50:50 MF/PVAc blends were higher than those of the other blends, especially of 100% PVAc or MF. We concluded that blends the MF/PVAc blend ratios correlate during the adhesion process.

• Journal of Information Display
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• v.4 no.1
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• pp.17-23
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• 2003

A thermoset type anisotropic conductive adhesive film (ACAF) comprising epoxy resin and natural butyl rubber (NBR) as the binder, micro-encapsulated imidazole as the curing agent, and Ni/Au coated polymer bead as a conductive particle has been studied. These films have been prepared to respond to requirements such as improved contact resistance, current status less of than 60 ${\mu}m$ and reliability. These films can also be used for connection between the ITO glass for LCD panel and the flexible circuit board. The curing conditions for the connection were 40, 20 and 15 seconds at 150, 170 and 190 $^{\circ}C$, respectively. The initial contact resistance and adhesion strength were 0.5 ${\Omega}/square$ and 0.4 kg/cm under the condition of 30 kgf/$^{cm}^2}$, respectively. After completing one thousand thermal shock cycling tests between -15 $^{\circ}C$ and 100 $^{\circ}C$, the contact resistance was maintained below 0.7 ${\Omega}/square$. Durability against high temperature (80$^{\circ}C$) and high humidity (85 % RH) was also tested to confirm long-term stability (1000 hrs) of the conduction.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.37-41
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• 2005

The curing of thermoset resin is accompanied with the changes in chemical and physical properties. The cure monitoring techniques can be designed by tracing these property changes. This paper presents the cure monitoring technique with fiber optic sensors to detect the change of refractive index during the polymerization process of engineering epoxy resin. The fiber optic sensor system was developed to measure the reflection coefficient at the interface between the fiber optic and the resin. The correlation between the sensor output and the degree of cure was performed following Lorentz-Lorenz law. The isothermal data from the sensors are compared with the data from differential scanning calorimeter.

• Transactions of Materials Processing
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• v.4 no.3
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• pp.245-256
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• 1995

SMC(Sheet Molding Compound), a thermoset composite material which consists of unsaturated polyester resin, fiberglass strands, fillers, and various chemical additives for curing agent, has been widely used in fabrication of structural components. The mechanical properties of molded SMS parts are strongly dependent on material flow results during compression molding process, while such flow in molds is affected by material characteristics. For numerical simulation of SMC molding process, estimation of material property of SMC must be accomplished. In this study, flow resistance of SMC was estimated through a simple compression test using a lubricant with grease oil under the constant strain rate condition at various temperatures and the result was compared with other material data available in the literature. The accuracy of the experimentally determined flow resistance was tested by finite element analyses of compression molding of SMC. Simulation results were compared with experimental results under the plane strain condition.