• Elastomers and Composites
• /
• v.50 no.2
• /
• pp.110-118
• /
• 2015

In this study, diethylaminoethyl methacrylate-styrene-butadiene terpolymer (DEAEMA-SBR), in which diethylaminoethyl methacrylate (DEAEMA) was introduced to the SBR molecule as a third monomer, was synthesized by cold emulsion polymerization. It is expected that amine group introduced to a rubber molecule would improve dispersion of silica by the formation of hydrogen bond (or ionic coupling) between the amine group and silanol groups of silica surface. The chemical structure of DEAEMA-SBR was analyzed using proton nuclear magnetic resonance spectroscopy (H-NMR), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Then, various properties of DEAEMA-SBR/silica composite such as crosslink density, bound rubber content, abrasion resistance, and mechanical properties were evaluated. As a result, bound rubber content and crosslink density of DEAEMA-SBR/silica compound were higher than those of the SBR 1721 composite. Abrasion resistance and moduli at 300% elongation of the DEAEMA-SBR/silica composite were better than those of SBR 1721 composite due to the high bound rubber content and crosslink density. These results are attributed to high affinity between DEAEMA-SBR and silica. The proposed study suggests that DEAEMA-SBR can help to improve mechanical properties and abrasion resistance of the tire tread part.

• Elastomers and Composites
• /
• v.38 no.2
• /
• pp.139-146
• /
• 2003

In this work, the influence of ozone treatment on surface properties of carbon black is investigated in terms of X-ray photoelectron spectroscopy (XPS) and contact angles. And their mechanical interfacial properties of the carbon black/acrylonitrile butadiene rubber (NBR) compounds are studied by the crosslink density and composite tearing energy ($G_{IIIC}$). As a result, it is found that the increasing of the ozone concentration leads to an increase of the introduction rate of oxygen-containing functional groups onto carbon black surfaces and to an increase of the surface free energy, resulting in improving both crosslink density and tearing energy ($G_{IIIC}$) of the compounds. The results can be explained by the fact that the oxygen-containing functional groups of carbon black surfaces make an increase of the degree of adhesion at interfaces between carbon blacks and rubber matrix.

• Elastomers and Composites
• /
• v.35 no.4
• /
• pp.288-295
• /
• 2000

It has been tried to decrease the crosslink density of vulcanized EPDM (ethylone-propylene-diene terpolymer) rubber through a chemical devulcanization treatment. Phase transfer catalyst, alkali metal (i.e., sodium), and triphenylphosphine have been used as a chemical agent ul the devulcanization treatment. Also it has been estimated the effect of the devulcanization treatment in the case of utilization of 2-butanol as a devulcanization reaction solvent. In the devulcanization treatment using quaternary ammonium salt as a phase transfer catalyst. the devulcanization effect has been studied with the variation of catalyst molecular weight and the choice of bromide or chloride cation. In the devulcanization treatment using sodium, it has been estimated the devulcanization treatment effect depending upon the variation of reaction variables such as amount of sodium used, reaction temperature, pressure of hydrogen gas, which is used as a reaction environment. The $M_c$ value (number average molecular weight between two crosslink points) has been experimentally estimated by the equilibrium swelling method and it is quantitatively related to the crosslink density. The estimation of devulcanization effect for vulcanized EPDM rubber has been carried out by the comparison of the $M_c$ values between the untreated and the treated specimens.

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

• Bulletin of the Korean Chemical Society
• /
• v.26 no.11
• /
• pp.1853-1855
• /
• 2005

• Bulletin of the Korean Chemical Society
• /
• v.27 no.3
• /
• pp.429-431
• /
• 2006

• Elastomers and Composites
• /
• v.51 no.3
• /
• pp.175-180
• /
• 2016

Influence of amino acidic chemical on properties of maleic anhydride-grafted ethylene-propylene-diene terpolymer/zinc oxide (EPDM-g-MAH/ZnO) composites was investigated. 4-Aminosalicylic acid (ASA), 4-amino-2-methoxybenzoic acid (AMBA), 12-aminolauric acid (ALA), and glutamine (Gln) were employed as the amino acidic chemicals. Though small quantity (0.5 phr) of the amino acidic chemical was added to the EPDM-g-MAH/ZnO composite, the properties were notably changed. By adding the amino acidic chemical, the percent crystallinity and apparent crosslink density were reduced. Order of the percent crystallinity was related to that of the $pK_a$ values of amino acidic chemicals. By adding the amino acidic chemical, the basic tensile properties were on the whole improved. The experimental results were explained by the $pK_a$ values of amino acidic chemicals, change of zinc ionomer formation, and interactions between the additive and EPDM-g-MAH chain.

• Elastomers and Composites
• /
• v.54 no.4
• /
• pp.330-334
• /
• 2019

Cryogenic crushing techniques have been employed for recycling waste rubber articles and for extracting residual organic additives present in rubber samples. Rubber particulate derived from tire tread abrasion is one of the key components of road dust. Therefore, in this work, we prepared rubber particulates using a cryogenic crusher and characterized their shapes as well as size distributions according to the type of rubber. The rubber particulates exhibited uneven surfaces with the presence of some small pieces. The order of the particle size distribution was observed to be: NR > BR > SBR. Subsequently, carbon black was added; this led to a decrease in the particle size and the shape becoming rougher. The crushed particulates of the carbon black-filled samples comprised agglomerated shapes of small pieces, which were similar in shape to that of wear debris in tire tread. It was discovered that crosslink density was one of the principal factors that led to the formation of small crushed particulates. The small particulates obtained by cryogenic crushing can be utilized as model rubber particulates for researching micro dust.

• Elastomers and Composites
• /
• v.40 no.2
• /
• pp.119-127
• /
• 2005

Material characteristics and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. In this paper, the material test and accelerated heat aging test were carried out to predict the useful life of NBR and EPDM rubber mount for a compression motor which is used in a refrigerator. In order to investigate the effects of heat-aging on the material properties, crosslink density, modulus at 100% strain, stress-strain curves were obtained from uniaxial and equi-biaxial tensile tests. The change of compression set were used for assessment of the useful life and the time to threshold value were plotted against the reciprocal of absolute temperature to give the Arrhenius plot. The useful life at variable temperatures are obtained in the Arrhenius relationship.

• Journal of Nutrition and Health
• /
• v.44 no.3
• /
• pp.189-195
• /
• 2011

Vitamin K has been suggested to plays a role in bone metabolism. The objective of this study was to determine whether vitamin K2 supplementation is related to bone mineral density, bone formation markers, and bone resorption in ovariectomized (OVX) rats. Forty Sprague-Dawley female rats (body weight, $200{\pm}10$ g) were divided into four groups: a sham group fed a control diet, a sham group fed a vitamin K2 supplemented diet, OVX fed a control diet, and OVX fed a vitamin $K_2$ supplemented diet (3.5 mg vitamin $K_2$/kg diet). All rats were fed the experimental diets for 6 weeks, and deionized water was provided ad libitum. Serum alkaline phosphatase activity (ALP), osteocalcin, and urinary deoxypyridinoline crosslink values were measured as markers of bone formation and resorption. Bone mineral density (BMD) and bone mineral content were measured in the spine and femur using PIXImus (GE Lunar Co., Madison, WI, USA). No significant differences in body weight gain, food intake, or food efficiency ratio were observed between the control and experimental groups. Serum ALP, osteocalcin, and urinary crosslink values were not significantly different between the vitamin $K_2$ supplemented groups. No significant differences were observed for any of the variables in the sham group. Spine BMD values were significantly lower in the OVX than those in the sham groups. Spine and femur BMD per weight of vitamin $K_2$ tended to be higher than the control diet group within the OVX group, but no significant differences were observed. In conclusion, dietary vitamin $K_2$ supplementation may have a beneficial effect on spine and femur BMD in OVX rats. Further research is needed to understand the potential benefits of vitamin $K_2$ on bone loss in OVX rats.