• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.371-376
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• 2001

The purpose of this study is to investigate toughening of unsaturated polyester resin by addition of polyuretane liquid rubber. In general, unsaturated polyester resin has strong brittleness in spite of its high strength Therefore; it is difficult to use unsaturated polyester mortar for the place where impact resistance is demanded. In this study, it was evaluated strength and Gf by using to polyurethane liquid rubber. As a result, the toughness of unsaturated polyester mortar was increased by polyuretane liquid rubber.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.129-134
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• 2001

The purpose of this study is to investigate properties of unsaturated polyester mortar using the shale as find aggregates. To evaluate properties of unsaturated polyester mortar using crushed sand from Black shale, Red shale, Gray shale, we peformed the experiment according the F/B ratio of 25, 30, 35% and the volume of fine aggregate of 50, 53, 56%. The Result of this study is as follows. the strength of unsaturated polyester mortar is higher than those of river sand. The F/B ratio is higher and the volume of find aggregate is lower, the strength of unsaturated polyester mortar is higher

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.379-382
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• 2003

In this study, methyl methacrylate (MMA)- modified unsaturated polyester mortar, in which the MMA was added to the unsaturated polyester resin, was developed for improving the early-age strength and the workability of the conventional polymer concrete, binder of which was the unsaturated polyester resin. Then the strength properties of the MMA-modified unsaturated polyester mortar were surveyed. The experimental results showed that early-age strength was greater when the MMA contents were increased in the range of $20{\sim}40%$, but the strength rather showed a tendency of decrease when the MMA contents was 50%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.536-538
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• 2011

In this study, the moisture absorption behaviors of the CNT reinforced unsaturated polyester composites were investigated along with exposure temperature and time. The tensile properties of the specimens were evaluated to identify the effect of absorbed moisture on the mechanical properties. The exposure temperatures of $25^{\circ}C$ and $75^{\circ}C$ were considered and the exposure time up to 600 hours was applied. According to the results, moisture absorption rate was increased as CNT content and exposure temperature were increased. The rate of decrease in tensile strength of the CNT reinforced unsaturated polyester composites was reduced due to the reinforcing effect of CNT compared to the unsaturated polyester resin.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.269-272
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• 2002

UV curing technology becomes important in various sectors of applications due to the high efficiency, environmental protection, and saving of energy. The effect of different proportion of vinylester (VE) and unsaturated polyester (UP) for VE/UP blend system was investigated in context of mechanical properties. The compositions of VE/UP blend were varied within 0:100, 20:80, 40:60, 60:40, 80:20, and 100:0 by weight percent. 1 wt% 1-hydroxy-cyclohexyl-phenyl-ketone was used as photoinitiator. The used intensity of UV light was in the range of $40~70 mW/\textrm{cm}^2$. The flexural strength of vinylester was not sensitive to the intensity of UV light. But the unsaturated polyester was very sensitive to the intensity of UV light. The flexural strength of vinylester was always superior to that of unsaturated polyester. The addition of the vinylester increased the flexural strength of blend system.

• Carbon letters
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• v.11 no.4
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• pp.285-292
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• 2010

Novel unsaturated polyester composites with PAN-based nanofiber, stabilized PAN nanofiber, and carbonized nanofiber webs have been fabricated, respectively, and the effects of the nanofiber web content on their electrical resistivity, the thermal stability, dynamic storage modulus, and fracture surfaces were studied. The result demonstrated that the introduction of just one single layer (which is corresponding to 2 wt.%) of the carbonized nanofiber web to unsaturated polyester resin (UPE) could contribute to reducing markedly the electrical resistivity of the resin reflecting the percolation threshold, to improving the storage modulus, and to increasing the thermal stability above $350^{\circ}C$. The effect on decreasing the resistivity and increasing the modulus was the greatest at the carbonized PAN nanofiber web content of 8 wt.%, particularly showing that the storage modulus was increased about 257~283% in the measuring temperature range of $-25^{\circ}C$ to $50^{\circ}C$. The result also exhibited that the carbonized PAN nanofibers were distributed uniformly and compactly in the unsaturated polyester, connecting the matrix three-dimensionally through the thickness direction of each specimen. It seemed that such the fiber distribution played a role in reducing the electrical resistivity as well as in improving the dynamic storage modulus.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1115-1120
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• 2000

The purpose of this study is to investigate toughening of unsaturated polyester resin by addition of liquid rubber. In general, unsaturated polyester liquid has strong brittleness in spite of if high strength Therefore; it is difficult use polyurethane liquid rubber for the place where impact resistance is demanded. In this study, it was evaluated strength, impact resistance and fracture toughness by adding to polyurethane liquid rubber(0~25%). As a result, it was found that a tendency to be increase bearing impact and fracture toughness as polyurethane liquid rubber increased but strength was decreased.

• Elastomers and Composites
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• v.54 no.3
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• pp.247-251
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• 2019

Two different urethane acrylates (mono-acrylate and di-acrylate) were used to prepare unsaturated polyester-based hybrid gel-coats. The physical properties and surface characteristics of these gel-coats were investigated on the basis of the content and type of urethane acrylate. The set-to-touch time increased and the physical properties (surface hardness and tensile strength) decreased with an increase in the urethane acrylate content. However, the type of urethane acrylate did not affect these parameters. It was found that the optimal urethane acrylate content for the application of unsaturated polyester-based hybrid gel-coats is ~10 wt%.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.6
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• pp.19-27
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• 2017

This study investigated to predict the compressive strength of unsaturated polyester resin based polymer concrete using the maturity method. The test results show that the development of the compressive strength increased exponentially until an age of 24 hours. After 24 hours, the development of the compressive strength just increased gradually. This test result shows that the strength of unsaturated polyester resin based polymer concrete was developed mainly at the early age. Estimated datum temperature of unsaturated polyester resin based polymer concrete was $-20.67^{\circ}C$ which was much lower than of datum temperature ($-10^{\circ}C$) of Portland cement concrete. Also, this study result shows that the existing maturity index associated with Portland cement concrete was not applicable for polymer concrete because curing time of Portland cement concrete is different clearly with curing time of polymer concrete. The cause of different curing time was that there were different curing mechanisms between Portland cement concrete and polymer concrete. In order to best apply the experimental data to a model, CurveExpert Professional, the commercial software, was used to determine the predictive model regarding the compressive strength of unsaturated polyester resin based polymer concrete. As a result, Gompertz Relation or Weibull Model was an appropriate model as a predictive model. The proposed model can be used to predict the compressive strength, especially, it is more useful when the maturity is in the range between $40^{\circ}C{\cdot}h^{0.4}$ and $900^{\circ}C{\cdot}h^{0.4}$.

• Polymer(Korea)
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• v.24 no.4
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• pp.459-468
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• 2000

To improve the mechanical properties of fiber-reinforced polymer matrix composites, laminated composites plates were fabricated using different matrix resins and glass or aramid fibers. The effect of matrix resin system were evaluated by tensile, flexural strength measurements. In the case of surface treated aramid fiber and unsaturated polyester resin composite, maximum flexural properties were observed in the composite prepared from the glass fiber treated with 0.5 wt% silane coupling agents. Vinylester resin composites show the highest tensile properties and isophthalic polyester composites have the highest flexural properties among the unsaturated polyester resin composites studied. The relationship between overlap laminated composites plates and mechanical properties of polymer composites is also investigated in order to improve mechanical properties of glass fiber and unsaturated polyester resin composites.