• Elastomers and Composites
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• v.53 no.3
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• pp.175-180
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• 2018

Solution-styrene-butadiene rubber (SSBR) composites were manufactured using four kinds of fillers: silica-silane coated carbon black (SC-CB) hybrid, starch-SC-CB hybrid, pure silica, and pure starch. The influence of filler type on the mechanical properties of the rubber matrix was studied in this work. SC-CB was prepared by silane-graft-coating using vinyl triethoxy silane and carbon black, which enhanced the dispersion effect between the rubber matrix and the filler, and improved the mechanical properties of the compounds. The morphology of the composites was observed by field-emission scanning electron microscopy (FE-SEM). The thermal decomposition behavior of the composites was determined by thermogravimetric analysis (TGA), and the crosslinking behavior of the composites was tested using a rubber process analyzer (RPA). The hardness, tensile strength, swelling ratio, and gas transmittance rate of the composites were evaluated according to ASTM. The test results revealed that with the addition of SC-CB, the hybrid fillers, especially those blended with silica, showed a better reinforcement effect, the highest hardness and tensile strength, and stable thermal decomposition behavior. This implies that the silica-SC-CB hybrid filler has a notable mechanical reinforcement effect on the SSBR matrix. Because of self-crosslinking during its synthesis, the starch-SC-CB hybrid filler produced the most dense matrix, which improved the anti-gas transmittance property. The composites with the hybrid fillers had better anti-swelling properties as compared to the neat SSBR composite, which was due to the hydrophilicity of silica and starch.

• Elastomers and Composites
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• v.45 no.1
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• pp.12-16
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• 2010

In this work, the effect of hydrophobic treated silica on the water absorption, thermal stabilities, and mechanical properties of the epoxy nanocomposites were investigated as a function of the silica content. As filler, fumed silica treated by dimethyldichlorosilane was used. It was found that the silica was well dispersed in the epoxy resins by the melt-mixing method with the addition of a silane coupling agent. The water absorption of the nanocomposites decreased with an increase of the silica content due to the effect of hydrophobic treated silica. The thermal properties, such as thermal degradation temperature, glass transition temperature ($T_g$), and coefficient of thermal expansion (CTE), of the nanocomposites were improved by the addition of silica. Furthermore, the mechanical properties of the nanocomposites, that is, the tensile strength and modulus, were enhanced with increasing silica content. This was attributed to the physically strong interaction between silica and epoxy resins.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.974-981
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• 2019

Fine dust has become a significant social problem. Diesel engines are used as the main propulsion power source in ships. This study introduces a diesel particulate filter (DPF) that is used as an exhaust after-treatment system for diesel engines to reduce particulate matter known as diesel fine dust. Two materials are used for the DPF: Cordierite and silicon carbide (SiC). In this study, to improve the physical properties of the binder used in the SiC DPF, cordialite was used instead of the SiC-based materials used as the conventional binder to evaluate the thermal durability against high-temperature deformation through the change of the coefficient of thermal expansion. In addition, the physical properties of the silica sol, as a main component of the base coating solution for determining the bond between the binder and the segment, were confirmed. Based on this, the change effect of the binder physical properties was confirmed through experiments by either adding a silane coupling agent or SiC to increase the reactivity of the silica sol.

• Polymer(Korea)
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• v.29 no.1
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• pp.102-105
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• 2005

Photoinitiated polymeric dental restorative nanocomposites (PDRNC) were designed to be useful for the variety of dental restoration. Hybrid-filler composed of barium silicate (avg. dia.:1 ${\mu}m$) and nano-sized silica (avg. dia: 40 and 7 nm) was adopted as a filler system. To improve the interfacial behavior with the resin matrix of bisphenol A glycerolate methacrylate/triethyleneglycol dimethacrylate (60/40 wt%), the surface of the filler was hydrophobically treated with a silane coupling agent. A visible light system of camphorquinone photo-initiator and 2-(dimethylamino)ethyl methacrylate photo-accelerator was utilized to activate the PDRNC. Esthetic properties of PDRNC was investigated by measuring the Hunter L, a, b values and it was discovered that PDRNC produced in this work showed excellent esthetic properties with an increase in 7 nm nanofiller content.

• Polymer(Korea)
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• v.32 no.6
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• pp.549-554
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• 2008

In order to synthesize polymer particle containing inorganic material, styrene and n-butylmethacrylate were copolymerized with alumina by dispersion polymerization. The weight ratio of styrene to n-butylmethacrylate was 3 : 1. A poly(N-vinyl pyrrolidon) was added as stabilizer. 2,2'-AzobisCisobutyronitrile) and 3-methacryloxypropyl trimethoxysilane were used as initiator and coupling agent, respectively. The weight ratio of 70 : 30 of isopropanol to distilled water was used as dispersion medium. According to the TEM measurement, we could confirm that alumina was dispersed into the polymer particle. The increase 'of concentration of alumina resulted in enhancement of particle size, but decreased its distribution. By the XRD method, it was found that the increase of alumina concentration showed the increase of intensity in peak and the increased 2$\theta$ value. From the TGA measurement, the increase of alumina concentration caused high heat resistance of the polymer. With respect to the type of initiator, the longer half life of initiator, the smaller particle size. We also found that the increase of particle stabilizer concentration made the decreased of particle size due to the accelerated generation of polymer particle in the early stage of reaction.

• Polymer(Korea)
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• v.37 no.6
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• pp.777-783
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• 2013

We used dipodal type bis[3-(trimethoxysilyl)propyl]amine (BTMA) silane coupling agent to modify silica nanoparticles to introduce secondary amino groups on the silica surface. These grafted N-H groups were reacted with glycidyl methacrylate (GMA) to introduce polymerizable methacrylate groups on the silica surface. After modification reaction, we used several analytical techniques such as Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA) and solid state $^{13}C$ cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR) to analyze the effects of reaction time, reaction temperature and used GMA concentration on the modification degree between N-H groups on the silica surface and epoxide groups of GMA. We found increased introduction of methacrylate groups on the silica surface by ring opening reaction of epoxide groups of GMA with N-H groups on BTMA treated silica with increased reaction time, reaction temperature and used GMA concentration within our experimental conditions.

• Journal of Radiation Industry
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• v.10 no.4
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• pp.181-187
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• 2016

Selective ${\beta}_1$-agonist and antagonists are used for the treatment of cardiac diseases including congestive heart failure, angina pectoris and arrhythmia. Selective ${\beta}_1$-antagonists including nebivolol have high binding affinity on ${\beta}_1$-adrenergic receptor, not ${\beta}_2$-receptor mainly expressed in smooth muscle. Nebivolol is one of most selective ${\beta}_1$-blockers in clinically used ${\beta}_1$-blockers including atenolol and bisoprolol. We tried to develop clinically useful cardiac PET tracers using a selective ${\beta}_1$-blocker. Nebivolol is $C_2$-symmetric and has two chromane moiety with a secondary amino alcohol and aromatic fluorine. We adopted the general synthetic strategy using epoxide ring opening reaction. Unlike formal synthesis of nebivolol, we prepared two chromane building blocks with fluorine and iodine which was transformed to diaryliodonium salt for labelling of $^{18}F$. Two epoxide building blocks were readily prepared from commercially available chromene carboxylic acids (1, 8). Then, the amino alcohol building block (15) was prepared by ammonolysis of epoxide (14) followed by coupling reaction with the other building block, epoxide (7). Diaryliodonium salt, a precursor for $^{18}F$-aromatic substitution, was synthesized in moderate yield which was readily subjected to $^{18}F$-aromatic substitution to give $^{18}F$-labelled nebivolol.

• Elastomers and Composites
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• v.49 no.2
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• pp.117-126
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• 2014

Methylene diisocyanate (MDI) was investigated as a novel interfacial modifier to enhance the performances of poly(methyl methacrylate)-modified starch/styrene-butadiene rubber (PMMA-modified starch/SBR) composites. Owing to the formation urethane linkage on one side and ${\pi}-{\pi}$ adhesion on the other side, MDI acted as an intermediated linkage role in the PMMA-modified starch/SBR interfaces, which was evidenced by the morphological, mechanical, dynamic mechanical and thermal decomposition studies. As a result, the presence of MDI significantly improved the mechanical properties and thermal stability of PMMA-modified starch/SBR composites. In addition, the effect of starch concentration on the various performances of the resulted MDI/PMMA-modified starch/SBR composites, such as morphology, vulcanization characteristics, mechanical properties, toluene swelling behavior, and thermal stability were investigated and discussed in detail. The obtained MDI/PMMA-modified starch/SBR composites exhibited superior mechanical properties to carbon black/SBR (CB/SBR) composites, demonstrating the potential use of the renewable starch as a substitute for CB in the rubber compounds.

• Polymer(Korea)
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• v.38 no.1
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• pp.62-68
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• 2014

To improve the compatibility of bentonite with rubber matrix, organo-modified bentonite was synthesized with a silane coupling agent, [3-(2-aminoethylamino)propyl]trimethoxysilane (AEAPTMS) in the suspension of bentonite. The structure and characteristics of organo-modified bentonite were investigated using FTIR-spectroscopy, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Ethylene-propylene-diene monomer (EPDM) rubber/organo-bentonite composites were compounded by a two-roll mill. The vulcanization and mechanical properties were studied. Results showed that the concentration of hydrochloric acid and $H_2O$ in the synthesis had significant influence on the modification of bentonite, which further contributed to the properties of the composites. Filled with 20 phr modified bentonite, the tensile strength and elongation at break of the rubber increased from 1.95 to 4.8 MPa and 300% to 500%, respectively.

• Journal of Adhesion and Interface
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• v.19 no.4
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• pp.154-162
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• 2018

Plasma treatment and corona treatment have been used for surface modification of polydimethylsiloxane (PDMS) film by activating its surface with the -OH group. Adhesion promoter or coupling agent was also used to improve adhesion of PDMS film with various materials. However, obtained hydrophilicity onto the surface of PDMS films with those processes was transient and vulnerable. In this study, a new alkoxysilane-functionalized acrylic polymer precursor was first synthesized by copolymerization process, and then was reacted with HO-terminated PDMS through condensation reaction to prepare a new surface modifier for PDMS film. The structure and molecular weight of the prepared surface modifier were confirmed by 1H-NMR and GPC measurement. Surface properties of surface modifier-coated PDMS films were also investigated by using XPS, ATR and WCA analysis. The adhesion between the PDMS film and the surface modifier was tested using cross-cut test.