• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.265-268
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• 2005

Thermoplastic elastormer (TPE) has many advantages such as high flexibility, high elasticity and high elongation, etc. TPE is easily molded such as plastic materials, therefore, many TPE parts are applied as home appliances and mechanical parts. However, if TPE is once molded, its mechanical properties are changed by injection molding conditions such as melt temperature, mold temperature, injection pressure and holding pressure, etc. In this study, the influences of the injection molding condition on the mechanical properties of thermoplastic vulcanizates(TPVs), which is one of the TPE, were investigated. By the injection molding experiment, as increasing the melt temperature, the tensile strength, shrinkage and hardness decreased. By the scanning electron microscope (SEM) analyzing the TPVs' crystallization, the morphology was affected by the melt temperature.

• Macromolecular Research
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• 제8권6호
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• pp.268-275
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• 2000

After imposing a large pre-strain, anisotropy increases with increasing residual extension ratio. Gums have very low residual extension ratio and exhibit little anisotropy, while black filled SBR and especially sulfur-cured carbon black filled NR have large set and anisotropy. For carbon black filled rubber, samples subjected to tensile loading in perpendicular to the pre-strain direction have the same stress-strain curves shape as the sample without pre-strain (=isotropic samples), but slightly lower modulus. However, compared to isotropic or perpendicular directional samples to pre-strain direction, samples subjected to tensile loading in parallel to the pre-strain direction show low stress at low deformation, but have high stiffness at high deformation. Normalized anisotropy changes with strain. The normalized anisotropy for various deformations is a linear function of residual extension ratio.

• Elastomers and Composites
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• 제9권1호
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• pp.5-13
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• 1974

The characteristics of IR and IR blended elastomers, for footwear by means of blending with NR and SBR, have been studied. The results obtained were as follows: 1. The mastication of IR was almost not required, where as NR and SBR are necessary. Therefore mixing time was much reduced because of speedy filler feeding. 2. Disadvantage of low Mooney viscosity was covered by blending with NR and SBR, and by loading filler. Superior flow property in comparison to other polymers was worthy and valuable in providing formulas for mould flow, 3. The elongation property of green stocks and vulcanizates was shown smooth surface for extruded and calendered stocks, and facilitated fabrication processes. 4. Because of slow vulcanization, IR is required to control vulcanization time by adding proper accelerators. This property, in turn, made possible to improve the storing stability of green stocks by controlling scorch time.

• Elastomers and Composites
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• 제27권4호
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• pp.281-288
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• 1992

The purpose for this study is to examine the vulcanization characteristics, especially the damping, elastic modulus and viscous modulus properties of filler 50phr filled NR compounds and to find out the compounds which can be used as damping materials in industry. For this study, compounds were prepared with filler filled compounding formula. Their vulcanization characteristics, elastic modulus, viscous modulus and damping properties were examined by mean of the rheometrics dynamic spectrometer. The results of this study can be summarized as follows. 1. The elastic modulus values of the maxium under the condition of 1Hz frequency, showed the order as follows, $HAF>Silica>FEF>GPF>SRF>Clay>CaCO_3\;coated>CaCO_3$. 2. The damping values of the maxium under the condition of 1Hz frequency, showed the order as follows $Silica>HAF>FEF>GPF>SRF>Clay>CaCO_3\;coated>CaCO_3$.

• Elastomers and Composites
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• 제27권4호
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• pp.247-254
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• 1992

The purpose of this dissertation is to study the vulcanization characteristics, compression set and other physical properties of NBR vulcanizates according to the various plasticizer and its content. Vulcanization characteristics were investigated by using cure that has obtained by means of rheometer and Mooney viscometer. The result of physical properties, vulcanization characteristics are as fellows. 1. The results of test for optimum cure time in vulcanization characteristics of NBR compounds indicated the rapidity of scorch time according to the increase of amounts of plasticizer. 2. In the test of compression set property, LCR was the best effect. 3. In the test of oil resistance, LCR was the best effect.

• Elastomers and Composites
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• 제13권2호
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• pp.89-98
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• 1978

1. The effect of reactive type antioxidant, G-1 in comparism to ordinary antioxidant, SP, which are used for NR and SBR has teen studied, and its recipes are equal. The effects against ozone aye been shown that ill ordinary antioxidant, SBR, no an particular effect both for NR and SBR was found, where as in reactive type, considerable influence was recogniged particulary in dynamic ozone test. 2. The influence of reactive antioxidants on velcanization has been studied by means of Mooney viscometer and Rheometer. 3. The ageing properties of vulcanizates containing reactive antioxidant have been studied in terms of tensile strength.

• Elastomers and Composites
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• 제1권1호
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• pp.56-62
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• 1966

The aging characteristics of vulcanized rubber products manufactured in Korean industries have been studied, especially in terms of relationship between aging temperature and time, and also the comparison of results between Geer's oven testing and tube testing was made. It was assessed from changes in tensile properties resulting from conditioning at elevated temperatures for specified period of time. Even though the recipe of each sample is different, the results, as would be expected, has shown that at lower aging temperature the change of tensile strength indicate moderately and at the elovated severely as shown in Figure 9. Consequently, in spite of that the results from conditioning at various temperatures for certain specified period of time must be equivalent to each other, it shows inignorable tolerance. The results of Geer's oven test and tube test have shown slightly different value. It seemed to be caused by the result of migration phenomena on aging in Geer's oven.

• Elastomers and Composites
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• 제18권3호
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• pp.87-98
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• 1983

Fundamental properties and surface treatment effects of domestic kaolin calcined at higher temperature were studied to develop reinforcing fillers for rubbers. The results obtained are as follows: (i) X-ray diffraction and scanning electron microscopy studies revealed kaolinite as a major constituent of the raw kaolin used in this study. (ii) Physical properties of natural rubber vulcanizates compounded with the calcined kaolin fillers treated with poly(maleic anhydride) and sodium polyphosphate are favorably improved. Particularly, the kaolin filler treated with sodium polyphosphate(designated as PT series) shows excellent physical properties compared with hydrated silica.

• 한국인쇄학회지
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• 제18권2호
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• pp.83-101
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• 2000

In this experiment butadiene rubber(BR)/acrylonitrile butadiene rubber(NBR) blends was prepared and then the applicability of BR/NBR blends as printing rubber roller was examined. With the aid of open 2-roll mill, BR, NBR and another chemical additives were compounded. Then rubber vulcanizates were manufactured by hot press and maximum torque, Mooney viscosity, mechanical properties and oil resistance of the test specimens were measured. With prolonged oil aged treating time, BR/NBR blends became soft and so the hardness of blends decreased. It could be explained by the swelling of rubber matrix with oil penetration in to rubber molecules. The undesirable low value of oil resistance of BR was significantly improved by blending BR with NBR.

• Macromolecular Research
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• 제9권6호
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• pp.319-326
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• 2001

Fatigue crack growth (FCG) behavior of natural rubber/ethylene-propylene-diene rubber (NR/EPDM) blend vulcanizates under dynamic tearing condition was investigated by using a fracture mechanics approach. It appeared that variation of crack growth rate with blend compositions was dependent on the level of imposed tearing energy G. At low tearing energy region, the FCG rates of the blend were lower as the EPDM content was increased, while at high tearing energy region, the trend was reversed. Over the measured range of tearing energy G, all blend compositions showed the lower crack growth rates compared to the average of properties of component elastomers. When the blends were thermally aged, the fatigue resistance of the blends was deteriorated in proportion to the concentration of EPDM phase. Fatigue crack growth behavior of the blends was supposed to be associated with the inhomogeneities of the crosslink structure of the blends arising from cure incompatibility of the EPDM and NR when they are sulphur cured.