• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.24-30
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• 2018

Various investigations of vegetable oil extracted from natural resources are underway because of their low cost and environmental value. On the other hand, the double bonds in vegetable oil should be substituted to other high reactive functional groups due to their low reactivity for synthesizing bio-polymeric materials. ${\alpha}$-eleostearic acid, which consists of a conjugated triene, is the main component of tung oil, and the conjugated triene allows tung oil to have higher reactivity than other vegetable oils. In this study, tung oil was copolymerized with styrene and divinylbenzene to make a thermoset resin without any substitution of functional groups. The thermal and mechanical properties were measured to examine the effects of the composition of each monomer on the synthesized thermoset resin. The results showed that the products have only one Tg, which means the synthesized thermoset resins are homogeneous at the molecular level. The mechanical properties show that tung oil acts as a soft segment in the copolymer and makes a more elastic product. On the other hand, divinylbenzene acts as a hard segment and makes a more brittle product.

• 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.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.61-65
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• 1998

Epoxy resins are currently one of the most widely used thermoset polymers. Applications on epoxy-based materials range from common to structural adhesives as well as to matrix materials for high performance composites. The outstanding versatility of this resin can be related to the reactivity of the epoxy group, which can be opened by a large number of different chemical compounds, such a aliphatic and aromatic amines, anhydrides and poly-amides. (omitted)

• Composites Research
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• v.28 no.3
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• pp.99-103
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• 2015

This paper presents the cure kinetics studies on the cure reaction of thermosetting resin. Above all, change in degree of cure and specific heat capacity according to temperature are observed using DSC and MDSC. The results are analyzed by cure kinetics and specific heat capacity model. Glass transition temperature was also measured to apply to the specific heat capacity model. Model parameters were gained from the modeling result. As a result, behavior of specific heat capacity can be calculated mathematically.

• Polymer(Korea)
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• v.28 no.1
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• pp.35-40
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• 2004

The formation mechanism of void defect which deteriorate composite's property is various according to each composite process. In this paper, void formation and growth mechanism is analyzed by thermal analysis and GC/MS. We made a vacuum chamber for observing pressure effect. Thermal analysis has been done in various condition. Elements of volatiles during resin curing were turned out by GC/MS. The most of volatiles of polyester were composed of styrene (over 80%) and a small quantity of toluene. In case epoxy resin, butyl glycidyl ether was the main element of volatiles (over 90%). We concluded that the original sites of void growth existed in resin and they were eliminated by vacuum and heating process. And the growth of void was influenced by water, diluents, solvent, and reactants in resin.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.9-17
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• 1999

Viscoelastic characteristics of cured phenolic resin/carbon fiber composite materials were investigated through glass transition and degradation reaction processes in the high temperature region up to $400^{\circ}C$. A typical glass transition of the cross-linked thermoset polymer was followed by irreversible degradation reactions, which were exhibited by the increasing storage modulus and loss modulus peak. A degradation master curve was constructed by using the vertical and horizontal shift factors, both of which complied well with the Arrhenius equation in light of the kinetic expression of degradation rate constants. Using an analogy to the Havriliak-Negami equation in dielectric relaxation phenomena, a viscoelastic modeling methodology was developed to characterize the frequency- and temperature-dependent complex moduli of the degrading thermoset polymer composite systems. The temperature-dependent relaxation time of the degrading composites was determined in a continuous fashion and showed a minimum relaxation time between the glass transition and degradation reaction regions. The capability of the developed modeling methodology was demonstrated by describing the complex behavior of the viscoelastic complex moduli of reacting phenolic resin composite systems.

• 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.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.317-322
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• 2012

The microstructures were examined by SEM, FT-IR spectra, tensible properties mole % of [NCO/OH], and particle size analyzer. Growing concerns in the environment-friendly industries have led to the development of solvent-free formulations that can be cured. We had synthesized the polyurethane resin having the ability to protect stainless steel against corrosion. Compared with general packing materials and coatings, this resin is highly stronger in intensity and longer durability. Polyurethane resins were composed of polyols, IPDI, silicone surfactant, catalyst and crosslink agent. Moreover, thermal fillers such as $Al_2O_3$, fume silica and $ZrO_2$ not only accelerated the curing rate but also improved the physical property as thermal barriers. The rigid segments of polyurethane in mechanical properties were due to crosslink agent and the increase of [NCO/OH]. In conclusion, the polyurethane microstructure with crosslink agent can be good material for themoset coating of metal substrates such as stainless steel.

• Design & Manufacturing
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• v.16 no.3
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• pp.44-49
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• 2022

In this study, the simulation of the resin transfer molding process method using MoldFlow has been investigated. This work explains the thermoset material model, fabric permeability model, the flow model and the cure model. It has been shown that the simulation result can predict filling and cure performances.

• 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.