• Elastomers and Composites
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• v.13 no.4
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• pp.277-281
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• 1978

1. A good retarder reacts fast with MBT and. forms a non-scorchy accelerator. 2. The decrease in cure rate$(k_1)$ is attributable to the slow cure rate of 2-cyclohexyldithiobenzothiazole(CDB). 3. Cyclohexyl polysulfides(CPS) and cyclohexylthioamine are believed to be also involved in the cure retardation. 4. The new retarder can stop crosslinking by intercepting the crosslink precursors. 5. Formation of cyclohexyl polysulfides and their lack of curing property may be responsible for the low state of cure when the new retarde is used. These results are schematically summarized in Figure 7.

• Elastomers and Composites
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• v.40 no.3
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• pp.181-187
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• 2005

Changes of physical properties or NR vulcanizates with different cure systems by thermal aging were investigated. Two sulfur cure systems and one resole cure system were employed, and total contents of the curatives were varied. For the NR vulcanizates with sulfur cure systems, hardness and modulus after the thermal aging at $90^{\circ}C$ for 3 days were increased, but elongation at break and tensile strength were decreased. For the NR vulcanizates with resloe cure system, the physical properties after the thermal aging were decreased. The change of physical properties by the thermal aging was explained with the crosslink density change. The crosslink densities or the NR vulcanizates with sulfur cure systems were increased after the thermal aging, but those with resole cure system were decreased. Influence of the migration of antidegradant on the changes of physical properties was also investigated. However, the changes of physical properties by the thermal aging were not explained sufficiently with the migration of antigradant.

• Design & Manufacturing
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• v.7 no.1
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• pp.60-63
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• 2013

Recently, Silicone that one of the thermo-sets is used to making optical products such as LED lenses because of excellent thermal properties. LED lenses are required to keep the precise dimensions, so they must be molded to have the minimum deformation. Thermo-sets have the expansion characteristic on the part of thermal property, it is important to optimize the cure condition so that the deformation of the part become minimum. In this study, to investigate the relationship between the shrinkage by the curing and expansion by the thermal properties of the resin, reactive injection experiment was performed by setting the variables such as mold setting temperature, cure time. As a result, it was confirmed that there was a interval while the thermal properties were transferred to more active during the cure process. It is expected to help in determining the reactive injection molding conditions of the thermo-set parts as well as LED lens in order to reduce the amount of deformation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.652-655
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• 2010

BBU attached to the 155mm is the weapon system for the extension of range through the reduction of base drag. This research focus on the development of inhibitor formulation changing cure agent from DDI to IPDI. Development process is as follows. First, the formulation test about basic property Second, the study on the application of process. Third, the tests for the quality and aging properties. The test results are satisfied with the all of the requirments. In results, this research is contributed to the stable manufacturing in the instability of supplying of cure agent.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4388-4397
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• 2015

The purpose of this study was to research the property change of acrylic resins depending on the induced-beam change and research the improved physical property of dry-heat and microwave-cured dental place acrylic resin in order to develop the acrylic resins with the optimum characteristic. As a result of observing flexural rigidity, hardness and color difference, the dry-heat-cured specimens of Vertex RS and Paladent 20 showed ideal property at 5, 15, and 25 kGy irradiation. The microwave-cured specimens of Vertex RS and Paladent 20 showed ideal property at 5 kGy irradiation. The correlation analysis showed a positive correlation among ARD, flexural rigidity (0 418), E coefficient (0.675) and Barcol hardness (0 588). The radiation cure technology is helpful for relieving the contamination caused by the manufacture of polymer composite. It can significantly contribute to the fusion of ultra violet cure technology and nano technology and the improvement of mechanical property without giving effect to the workability of polymer.

• Composites Research
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• v.33 no.5
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• pp.302-308
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• 2020

We measured the thermal conductivity of composite materials manufactured by the autoclave and vacuum bag only processes and predicted the cure behavior of the external and internal of composite parts with a cure kinetics model. The temperature difference between the external and internal depends on the processes because of the change of thermal conductivity. In the autoclave process, the temperature and cure behavior of the internal were similar to those of the external because of the high thermal conductivity. However, the temperature of the internal of the vacuum bag only process was different from that of the external. The difference can influence the part quality and evacuation of air. Compression tests were performed to find the mechanical property using 0° unidirectional specimens. The composite of the vacuum bag only process was found to have a lower compressive strength than that of the autoclave process.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.2
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• pp.1-5
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• 2000

The silane compounds as a coupling agent have been used in the propellant in order to enhance the mechanical property and lower the viscosity. They showed great effects in the PEG propellant. In PCP propellant, however, the silane compounds not only made a severe cure problem but also deteriorated the mechanical property. In this study, TESPN as a silane compound was applied in PEG and PCP binder for finding above factors. The main reason was that the main chains of PCP were broken due to the trans-esterification reaction of ester groups in PCP and alchol which was produced by reacting silane compounds and moisture in the solution of liquid binder.

• Fire Science and Engineering
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• v.16 no.4
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• pp.65-71
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• 2002

In this paper, the thermal and flame properties of GFRP with various flame retardant(aluminum trihydrate, antimony trioxide) compositions have been investigated by thermal analysis and flammability tests(LOI test, flammability 45 degree test). The flame and mechanical properties(hardness, tensile strength, modulus) of general purpose grade glass fiber/unsaturated polyester composite with flame retardant composition have been also evaluated. The effect of cure pressure on the flame properties of aerospace grade glass fiber/epoxy composite was investigated. Considering the flame and mechanical property of composite, we could determine the optimum flame retardant composition(ATH 10∼20 phr). Test results show that the flame property of glass fiber/epoxy composite is considerably affected by cure pressure conditions.

• Elastomers and Composites
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• v.35 no.3
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• pp.173-179
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• 2000

Cure characteristics. tensile properties, and dynamic properties were investigated on the carbon black-filled natural rubber compounds, in which three typical vulcanization types conventional vulcanization(Conv), semi-efficient(Semi-EV), and efficient(EV) vulcanizations were used. The effects of vulcanization temperature on both the mechanical property and aging resistance of rubber compounds were also investigated. The Conv cure system showed a slightly slower rate of vulcanization than those of Semi-EV and EV ones. On the other hand, it showed a higher value in the maximum torque of cure curve. Higher tensile moduli were observed in Conv system than those in Semi-EV and EV ones, while lower elongation at break were obtained in Conv one. The tensile strength at break were found to be about the same for three cute systems. Hardness, modulus, and tensile strength decreased with increasing the vulcanization temperature, and the degree of changes in the properties was found to be smaller for EV and Semi-EV systems than that in Conv one. The EV system was found to be superior in thermal-aging resistance to Conv one.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.963-969
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• 1996

Cure characteristics of DGEBA(diglycidyl ether of bisphenol A)/dicy(dicyandiamide) system containing diuron(3-(3,4-dichloro phenyl) -1,1-dimethylurea) as an accelerator was investigated. The system has shelf life of six months because dicy is insoluble in liquid/solid resins at room temperature. It is generally known that dicy is an adequate curing agent for one component adhesive due to its highly latent property. With increasing the amount of added dicy, reaction heat of DGEBA/dicy system increased and degree of conversion was not varied. For DGEBA/dicy/diuron system, cure temperature decreased about $40^{\circ}C$ and cure reaction became fast by the addition of diuron which activates dicy. $T_g$ of the mixed resin decreased with the amount of accelerator. which was interpreated with molecular structure forming loose chain. Cure kinetics of DGEBA/dicy and DGEBA/dicy/diuron system were explained using Kamal's autocatalytic reaction model. The effect of acceleration was confirmed with that reaction model.