• Elastomers and Composites
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• v.47 no.2
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• pp.129-140
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• 2012

The objective of this study was to estimate the practical recycling rate of plastic products, so that the study was conducted to build material flow diagram for PVC profile. For this objective, product generation, waste generation and recycling status were investigated. Using collected and analyzed status data, analysis of material flow by product and building material flow diagram were conducted. As result of estimating the recycling rate by product, The sum of domestic demand was 525,448 ton and waste generation was 105,853ton in PVC flooring and profile. The sum of generation of recycling product and raw material was investigated to be 76,004ton(14.46%), which is higher compared to recycling obligation(8.5%) in 2009. To build the material flow diagram in the years(5~20years) ahead, prediction of future demand was based on the assumption that there will be no difference in annual generation of current and future. As the recycling rate of flooring and profile increases, it is estimated to reach 20% in 2013 according to the material flow diagram.

• Elastomers and Composites
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• v.46 no.1
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• pp.70-77
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• 2011

A new piece of test equipment, the slurry wear tester (SWT), was proposed in this study to evaluate the wear behavior of rubber vulcanizate in environmental contact with slurry. Natural rubber (NR) and chloroprene rubber (CR) were chosen as the basic matrices to test the slurry wear. The fluids used to fill the chamber of the SWT were 35% HCl and NaCl solution. The Akron abrasion test was used for comparison with SWT. According to the results of the Akron abrasion test, CR vulcanizate abraded more rapidly than NR vulcanizate under same test condition. It was found that the hysteresis of rubber was key factor contribute to the wear behavior. However, the slurry wear rate of the NR and CR vulcanizates did not change significantly, even with changes in the concentration of acid and the immersion time in both HCl and NaCl solutions; the fluid decreased the friction between the abrasive paper and the specimen. It also reduced the heat generated from repeated deformation and wear debris at the surface of the SWT's abrasion arm. Thus, these phenomena affected the wear behavior of rubber vulcanizate and caused different results in the conventional Akron abrasion test. This outcome could have resulted in an incorrect analysis if the slurry wear behavior of the rubber vulcanizate was estimated by the conventional abrasion tests, which are operated under dry conditions.

• Elastomers and Composites
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• v.49 no.4
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• pp.323-329
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• 2014

In order to select polymer matrix for MIF (Molded-In Foaming) process, in this study, we investigated rheological properties of commercial polymers, SBC (Styrene-Butadiene Copolymers, K-resin KK38) and SBS (Styrene- Butadiene-Styrene, KTR 101 and KTR 301). In time sweep test, the rheological properties ($G^{\prime}$, $G^{{\prime}{\prime}}$, ${\eta}^*$) of SBS at 155 and $170^{\circ}C$ display almost constant value as a function of time from 0 s to 1800 s. On contrast, the rheological properties of SBS at 185 and $200^{\circ}C$ exponentially increase as a function of time. It could be due to gelation of SBS at high temperature conditions. These increment of rheological properties are not observed in SBC. From LAOS (large amplitude oscillatory shear) test, the nonlinear rheological properties of SBS at 155 and $200^{\circ}C$ after 1800 s are compared. The nonlinear rheological properties at $155^{\circ}C$ show simple strain thinning behavior such as linear homopolymer, however, the nonlinear rheological properties at $200^{\circ}C$ show 2 times strain thinning behavior (Payne effect). It well match with the gelation of SBS at $200^{\circ}C$. From rheological studies, it is confirmed that the proper polymer matrix for MIF process (low rheological properties at initial time and high rheological properties after process) is SBS KTR 301.

• Elastomers and Composites
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• v.48 no.1
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• pp.10-17
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• 2013

Polyolefin-g-poly(t-butylstyrene) as one of the high-temperature polyolefin-based thermoplastic elastomers was synthesized by the graft-from anionic living polymerization from the styrene moieties of the linear poly(ethylene-ter-1-hexene-ter-divinylbenzene) as a soft block to form the hard end blocks, poly(t-butylstyrene). The chemistry of the anionic graft-from polymerization involved complete lithiation of the pendant styrene unit of the soft polyolefin elastomer with sec-BuLi/TMEDA followed by the subsequent graft anionic polymerization of 4-tert-butylstyrene with Mn=10,000~30,000 g/mol. The graft-from living anionic polymerization were very effective and the grafting size increased proportionally with increasing monomer concentration and the reaction times. The synthetic methodology for the multi-hydroxyl chain-end modified polyolefin-g-poly(t-butylstyrene) was proposed by using the thiol-ene click reaction between 2-mercaptoethanol and the polyolefin-g-[poly(t-butylstyrene)-b-high vinyl polyisoprene], which was obtained from the subsequent living block copolymerization using polyolefin-g-Poly(t-butylstyrene) with isoprene. The result indicated that this process produced a new well-defined functionalized graft-type polyolefin-based TPE with high $T_g$ hard block(> $145^{\circ}C$).

• Elastomers and Composites
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• v.48 no.1
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• pp.67-75
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• 2013

E-TPE (Engineering Thermoplastic Polyether Ester) was Ester Elastomer with functional groups as recycling and fast processability. In addition, if the car's lightweight enough to highlight eco-friendly materials that help to improve fuel economy has become. Have all the attributes of the rubber and engineering plastics E-TPE the available temperature area is spacious, heat resistance and oil resistance is excellent but getting attention as a new material in the field of auto parts in the field of electrical and electronic domestic depends entirely on imports by the lack of core technology and has been research and development is urgently needed. In this study, the hard segments, polyester (TPEE) as the base soft elastomers of the segments Ethylen-prophylene-Copolymer and CSM (Choloro sulphonated polyethylene Rubber), VAMAC (Ethylene Acrylic Rubber), NBR (Acrylonitrin Butadiene Rubber), 1, 3-Phenylene-bisoxazoline is dealing with Dynamic Vulcanized by content and added rubber properties, thermal variation observed. As a result, the properties of the dynamic vulcanization with NBR compared to other rubber heat resistance and oil resistance is on the increase.

• Elastomers and Composites
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• v.48 no.1
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• pp.61-66
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• 2013

A family of Cr(III) complexes supported on tridentate dibenzimidazolyl ligands having a general formula: $[N(CH_3)(CH_2)_2(Bm-R)_2]CrCl_3$ [where Bm = benzimidazolyl, R = H (3a); -Me(3b); -Bn (3c)] have been synthesized and utilized them for the trans-1,4-specific polymerizations of 1,3-butadiene (BD), activated with methylalumoxane (MAO). The activity of BD polymerizations was sensitive to the type of ligand on the Cr metal, so that the activity decreases in the order of 3a > 3c > 3b. All the catalysts combined with MAO yielded polybutadienes with perfect trans-1,4 structure with moderate molecular weight.

• Elastomers and Composites
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• v.48 no.1
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• pp.55-60
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• 2013

Swelling behaviors of raw (Specimen-R) and compressed (Specimen-C) samples of maleic anhydride-grafted EPDM (MAH-g-EPDM) depending on the treatment with dichloroacetic acid were investigated. Structural characteristics of the samples were analyzed by nuclear magnetic resonance spectroscopy (NMR) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). When the samples were not treated with dichloroacetic acid, the swelling ratio of Specimen-R was greater than that of Specimen-C by about twice and the swelling ratio change was negligible though the process of swelling and drying was repeated. When the samples were treated with dichloroacetic acid, the first swelling ratios were increased but the second ones were decreased. For the Specimen-C, the swelling ratio of the sample without the dichloroacetic acid treatment and the second swelling ratio of the sample treated with dichloroacetic acid were nearly the same. However, for the Specimen-R, the second swelling ratio of the sample treated with dichloroacetic acid was strikingly lower than that of the sample without the dichloroacetic acid treatment. The swelling ratio change according to the dichloroacetic acid treatment was explained by dissociation of the existing crosslinks and formation of new crosslinks.

• Elastomers and Composites
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• v.48 no.1
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• pp.39-45
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• 2013

Melt grafting of citraconic acid (CCA) onto an ethylene-propylene-diene terpolymer (EPDM) with various peroxide initiators was performed using a Haake Rheocorder. Finding the optimum running condition and concentration is critical for effective grafting and performance of grafted material. Therefore, this study focused on the effects of mixing (reaction) condition and monomer/initiator dosages on the grafting degree, grafting efficiency and crosslinking degree (gel content), melt flow index and mechanical properties of CCA-g-EPDM. As the grafting degree/crosslinking degrees increased, the tensile strength increased significantly, but elongation at break and melt flow index decreased. The initiator 2,5-dimethyl-2,5-di(tert-butyl peroxy)-hexane (T-101) appeared to meet for the best grafting(2.31%). The grafting degree increased markedly with increasing monomer CCA/initiator T-101 contents. The grafting degree also increased with increasing mixing temperature/time, and then leveled off or decreased/increased a little. The optimum monomer/initiator dosages and reaction temperature/time were found to be about 5/0.05 wt% and $180^{\circ}C$/15min, respectively.

• The Korean Journal of Zoology
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• v.36 no.3
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• pp.319-328
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• 1993

All vertebrates other than lampreys exhibit multiple loci encoding lactate dehydrogenase (EC 1.1.1.27,LDH). From the result shown by cellulose acetate and starch gel electrophoresis, the lampreys were-reported to have only one isozyme. However in our results the LDH of skeletal muscle, heart and kidney in Lampetra japonica were separated into three isozymes and that of liver was separated into two isozymes by polyacrylamide gel electrophoresis. The LDH of skeletal muscle and heart were separated into four isozymes and that of liver was separated into two isozymes by polyacrylamide gel isoelectric focusing (PAGlEF). The LDH of skeletal muscle were separated into four isozymes through the chromatofocusing. The molecular weight of LDH isozymes in skeletal muscle was approximately estimated to be 140,000 by Sephadex G-200 gel filtration. The LDH isozymes of skeletal muscle, heart and liver were inhibited by pyruvate to the nearly similar degree. And the degree of inhibition by pyruvate showed the value between LDH A$_4$and LDH B$_4$isozyme. And the LDH isozymes in heart, liver and skeletal muscle were thermostable. The results mentioned above indicate that the LDH isozyme in lamprey (Lampetra japonica) has not one isozyme but isozymes. And it is also found out that the two structures of their subunits are similar each others.

• Food Science and Preservation
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• v.18 no.4
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• pp.590-596
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• 2011

Pimpinella brachycarpa, called as cham-na-mul in Korea, is an edible popular herb. However, the study of biological activity of P. brachycarpa is still rudimentary in worldwide. In this study, from the cultivated P. brachycarpa, we prepared the methanol extract and its subsequent solvent fractions, and their antimicrobial, antioxidation, and anti-proliferative activities were evaluated. The fraction yields of n-hexane (H), methylene chloride (EC), ethylacetate (EA), butanol (B), and water residue (W) from the methanol extract were 18.71, 0.7, 0.56, 4.57, and 71.51%, respectively. Analysis of total flavonoid and total polyphenol showed that the EA fraction contained the highest contents (89.23 and 200 mg/g), and the W residue has the lowest contents (19.6 and 2.27 mg/g) among the factions. In antimicrobial activity assay, the EA fraction showed a broad-range antibacterial activity, while the H fraction is effective against gram positive bacteria. In antioxidation activity assay, EA and B fraction showed strong DPPH anion and ABTS cation scavenging activities including reducing power, and Hand MC fraction showed effective nitrite scavenging activity (71.43~83.82 ${\mu}g$/mL of $IC_{50}$). In a while, only B fraction showed strong anti-proliferative activity against human colorectal cancer HCT-116 (166 ${\mu}g$/mL of $IC_{50}$) as a dose-dependent manner up to 200 ${\mu}g$/mL. These results suggest that the EA and B fraction of P. brachycarpa could be developed as functional food ingredients.