• Elastomers and Composites
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• v.35 no.2
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• pp.122-131
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• 2000

In this work, the effect of chemical surface treatments on morphology of carbon blacks was investigated in terms of cure behavior and tearing energy ($G_T$) of carbon blacks/rubber composites. As experimental results, the polar or nonpolar chemical treatment led to a significant physical change of carbon black morphology. The cure activation energies (Ea) and frequency factor (A) obtained from Kissinger equation decreased with improving the dispersion of carbon flacks, resulting in high reactivity. However, a significant advantage of carbon black/rubber composites is gained by carbon blacks treated in basic (BCB) or nonpolar (NCB) chemical solution, resulting in increasing the tearing energy. These results could be explained by changes of dispersion, agglomerate, surface functional group, void volume, and cross-linking density of carbon black/rubber composites.

• Journal of the Korea Institute of Building Construction
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• v.5 no.4 s.18
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• pp.115-120
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• 2005

In recent years, polymer-modified mortars using polymer dispersions have been widely used as finish and repair materials in the construction industry because of their excellent properties compares to those of ordinary cement mortar. Especially, the adhesion improvement of ordinary cement mortar and concrete has attracted a great deal of attention from researchers, and several unique and simply applicable techniques for the adhesion improvement have been developed. The purpose of this study is to evaluate the abrasion resistance of polymer-modified mortar according various curing methods. The polymer-modified mortar are prepared with various polymer-cement ratios, and are subjected to three curing methods such as dry rure, standard cure and freezing and thawing cure after two curing methods, and then tested for abrasion. From the test results, the polymer-modified mortars with various polymer-cement ratios have some superior abrasion resistance compared with plain mortar. The abrasion resistance of polymer-modified mortars increase with an increase in the polymer-cement ratio, and is better under water cure than any other curing methods. It is concluded that the abrasion resistance of cement mortar is markedly improved by modifying of polymer dispersion.

• Macromolecular Research
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• v.9 no.2
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• pp.92-99
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• 2001

Silica-filled rubber compounds have slower cure characteristics than carbon black-filled ones due to the adsorption of curatives on the silica surface. Fatty acid was used as a cure activator along with zinc oxide in a sulfur cure system. Poly(ethylene glycol), PEG, was used in silica-filled rubber compounds to prevent adsorption of the curatives on the silica surface. In this study, influence of the size of fatty acid and PEG on properties of silica-filled NR compounds was investigated. It was found that the size of fatty acid and PEG affected the curt: characteristics and physical properties. The cure rate becomes faster as the PEG size increases. By increasing the size of fatty acid or PEG, the delta torque of the compound decreases while the Mooney viscosity increases. The modulus of the vulcanizate decreases with increasing the molecular weight of fatty acid or PEG. The experimental results were explained by the filler dispersion and by the prevention of the curative-adsorption on the silica surface.

• Microbiology and Biotechnology Letters
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• v.49 no.4
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• pp.493-500
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• 2021

Argyrins are a group of anticancer and antibacterial octapeptide bioactive substances isolated from myxobacteria. In this study, we showed that the myxobacterium Archangium gephyra MEHO_001, isolated in Korea, produces argyrins A and B. MEHO_001 cells tend to aggregate when cultured in liquid media. Hence, a dispersion mutant, MEHO_002, was isolated from MEHO_001. The MEHO_002 strain produced approximately 3.5 times more argyrins than that produced by the wild-type strain MEHO_001. We determined the whole-genome sequence of A. gephyra MEHO_002 and identified a putative argyrin biosynthetic gene cluster comprising five genes, arg1-arg5, encoding non-ribosomal peptide synthases and tailoring enzymes. Inactivation of arg2 by plasmid insertion disrupted argyrin production. The amino acid sequences of the proteins encoded by arg2-arg5 of A. gephyra MEHO_002 were 90-98% similar to those encoded by the argyrin biosynthetic genes of Cystobacter sp. SBCb004, an argyrin-producing myxobacterium with identical domain organization.

• Elastomers and Composites
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• v.37 no.4
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• pp.217-223
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• 2002

Silica-filled rubber compounds show poor filler dispersion and slow cure characteristics compared to carbon black-filled ones. In general, a silica-filled rubber compound contains silane coupling agent (bis-(3-(triethoxysilyl)-propyl)-tetrasulfide, TESPT) and diphenylguanidine (DPG) to improve the filler dispersion and to make fast cure characteristics. Acrylonitrile-butadiene rubber (NBR) improves the filler dispersion in silica-filled styrene-butadiene rubber (SBR) compounds. In this study, effect of NBR on the properties of silica-filled SBR compounds was investigated. Properties of the compounds which contain NBR without DPG or with small amount of TESPT (Compound A) were compared with those of the compounds which contain TESPT and DPG without NBR (Compound B). Scorch time of Compound A is faster than those of Compound B. Modulus and tensile strength of Comound A are slightly lower than those of Compound B. Traction property of the Comound A is better than that of the Compound B. Addition of NBR leads to reduction of the used amount of TESPT and DPG.

• Elastomers and Composites
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• v.41 no.1
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• pp.10-18
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• 2006

Influence of low molecular weight polybutadiene (liquid PB) treated with maleic anhydride on properties of a silica-filled SBR compounds was studied. Silica dispersion was improved by adding liquid PB. The liquid PB treated with maleic anhydride (liquid MAPB) was found to be more effective for the improvement of silica dispersion than the liquid PB without maleic anhydride (liquid NPB). Viscosity of the SBR compound decreased by adding the liquid PB. The crosslink density decreased with increase of the liquid PB content and the cure rate became slower with increasing the liquid PB content. Considering the experimental results, it was believed that addition of small amount of the liquid PB (less than 5 phr) was desirable to improve properties of silica-filled SBR compounds.

• Textile Coloration and Finishing
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• v.14 no.4
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• pp.223-228
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• 2002

Cotton fabric was treated with $TiO_2$-PEG600 dispersion colloid by pad-dry-cure and wet-fixation process to improve the performance properties as well as UV-cut effect. As the concentration of $TiO_2$/PEG increased tensile strength, crease resistance, stiffness of treated cotton fabric increased. Application of wet-fixation method provided a further improvement in tensile strength, crease resistance, stiffness of treated cotton fabric. Cotton fabric treated with $TiO_2$/PEG was more efficient in UV-cut property than untreated cotton.

• Elastomers and Composites
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• v.40 no.1
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• pp.29-36
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• 2005

Mixing condition and procedure affect properties or a filled rubber compound such as filler dispersion, viscosity, and bound rubber formation. Influence of separate load of styrene-butadiene rubber (SBR) and acrylonitrile-butadiene rubber (NBR) on properties or silica-filled SBR compounds containing NBR was studied. Cure time and cure rate became faster as NBR content increased. The crosslink density increased with increase in the NBR content. The bound rubber content also increased as the NBR content increased. NBR content of the bound rubber was higher than that of the compounded rubber. The bound rubber content was higher when SBR and NBR were loaded separately than when loading simultaneously. The cure time and cure rate were slower for the separate load than for the simultaneous one. The crosslink density was also lower for the former case than for the latter one.

• Elastomers and Composites
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• v.45 no.3
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• pp.223-229
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• 2010

We investigated the effects of processing geometry of silica-filled isobutylene-isoprene rubber (IIR) compounds on its mechanical properties and silica dispersion, using a two roll mill and an internal mixer (banbury mixer). The compound processed with the two roll mill showed the longer induction time ($t_2$), higher maximum torque ($T_{max}$), and better silica dispersion than the compound processed with the internal mixer; however, showed slightly the lower cure index ($t_{90}$). The mechanical properties (hardness, 300% modulus, tensile strength, elongation) of the compound processed with two roll mill were higher than compound done with the internal mixer.

• Elastomers and Composites
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• v.29 no.1
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• pp.18-29
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• 1994

The purpose of this study is to investigate reinforced effect between silica treated by coupling agents and rubber matrix under the configuration chemical bonds, and the effect of silica particles coated by organic polymers using aluminum chloride as the catalyst. In vulcanization characteristies were tested by Curastometer. The M-series vulcanizates were reached to the fastest optimum cure $time(t_{90})$ and R-series vulcanizates with the same formula had the shorted optimum cure times. Tensile characteristics measuring with a tensile tester revealed that the M-series vulcanizate was the best in the physical properties, such as tensile strength. In 100% modulus, however, the S-series vulcanizates appeared to be better than the other vulcanizates. Also, hardness showed the following order : S-series>R-series>M-series with the order of elongation R-series>M-series>S-series. In SEM test, shapes of chemical treated silicas were observed. The dispersion of filler in the SBR composite appeard uniformly. In RDS test for the dynamic characteristics, G' indicates that S-3 shows the highest value with the next order M-3>R-3, and the order of damping values are as followe: M-3>M-3>R-3.