• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.152-152
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• 2006

Polyolefins show a very healthy growth rate among commodity polymer resins due to their low feedstock prices, recyclable and environmentally friendly characteristics and easily controllable performances. Capacity investment in polyolefin field is now moving from technology region to consumer region and feedstock region. Therefore, key success factors for polyolefin business in the other region such as Korea are cost reduction, development of highly value-added products and new applications and substitution of PVC, PS, PET and other EPs. To add additional value to commodity polyolefin products, high level of platform technology such as catalyst, process and structure-properties relationship is needed. Progress on polyolefin products has been very closely related to catalyst and process technology. According to this trend, SK Corporation has devoted a lot of research effort into development of new value-added polyolefin products based on the proprietary technology platform.

• Computers and Concrete
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• v.9 no.6
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• pp.457-467
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• 2012

This study evaluates the permeability of cement-based composites, which are a mix of polyolefin fibers and silica fume. Test results indicate that permeability increases as the water/cementitious ratio increases. Silica fume in cement-based composites produced hydrated calcium silicate and filled the pores. However, permeability decreased as the addition of silica fume increased. Specimens containing polyolefin fibers also provided higher permeability resistance. The polyolefin fiber length did not have a significant effect on permeability. The decrease in the permeability is mainly due to the addition of silica fume and lower water/cementitious ratio. Addition of fibers marginally decreases the permeability. Incorporating polyolefin fiber and silica fume in composites achieved more significant decreases in permeability. The correlated test results reveal the interrelationship between them.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.7-10
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• 2002

In this study, polyolefin compounds were developed and evaluated for replacing a jacket material of URD power cables. The characteristics of compounds were investigated by water vapor transmission (WVT) test and mechanical test. In WVT test, all polyolefin compounds showed the superior water resistance to conventional PVC. The molecular structure and density of polyolefin play an important role in WVT. Also, polyolefin compounds showed the suitable characteristics in mechanical test. Especially, polyolefin compounds having linear molecules showed the superior characteristics to LDPE ones. From this study, it can be considered that polyolefin compounds may be suitable to jacket material for URD power cables.

• Elastomers and Composites
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• v.48 no.1
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• pp.30-38
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• 2013

Polyolefin is one of the most important commodity polymers having excellent physical properties and cost competitiveness, which has continuously broadened their market in response to a heavy demand from industry. However, the lack of polarity in polyolefin has limited its applications, especially where interactions with other materials are important. In view of the above, the incorporation of polar functional groups in polyolefin has been widely attempted. Especially, the preparations of segmented modified polyolefin copolymers, such as block and graft copolymers have been extensively investigated, since the loss of the original properties of polyolefin can be minimized while the polar segments can endow interactions with other materials. Living radical polymerization (LRP) method can be one of the most attractive synthetic tools for the preparation of the modified polyolefin block or graft copolymers. In this review, progress on the preparation of the polyolefin based block or graft copolymers through LRP technique is briefly summarized.

• 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(> $145^{\circ}C$).

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.15-22
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• 2008

Polyolefin block copolymer has been taking a great deal of attention due to their great potential in polymer industry since a new metallocene catalytic method for producing polyolefin block copolymer was developed by Dow Chemicals. However, so far, there was no systematic study of olefin block copolymer. In this review, Linear polyolefin block copolymers, containing semicrystalline poly (ethylene) (E) blocks and a rubbery block as a thermoplastic elastomer, were investigated in the viewpoint of microphase separation mode, microstructure, deformation behavior, and molecular architecture.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.251-260
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• 2011

In this study, the effect of natural jute fiber volume fraction on the bond characteristics of polyolefin based macro fiber in natural jute fiber reinforced cement composites, including bond strength, interface toughness, and microstructure analysis are presented. The experimental results on polyolefin based macro fiber pullout test of different conditions are reported. Natural jute fiber volume fractions ranging from 0.1% to 0.2% are used in the mix proportions. Pullout tests are conducted to measure the bond characteristics of polyolefin based macro fiber from natural jute fiber reinforced cement composites. Test results are found that the incorporation of natural jute fiber can effectively enhance the polyolefin based macro fiber-cement matrix interfacial properties. The bond strength and interface toughness between polyolefin based macro fiber and natural jute fiber reinforced cement composites increases with the volume fraction of natural jute fiber. The microstructural observation confirms the findings on the interface bond mechanism drawn from the fiber pullout test results.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.511-516
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• 2009

Photodegradation characteristics of polyolefin composites were studied. Thermogravimetric analysis results suggest that the polyolefin blends used in this study have different amounts of talc. The mechanical behaviors of polyolefin blends, which experienced UV-irradiation in accordance with SAE J1960, are investigated using tensile and Izod impact tests. These results show that as the UV-exposure time increases, a significant drop in the elongation at break and impact strength at a low temperature are observed. This may be explained by the decreases in elastic energy derived from the scission of polymer molecular chains and the low density of entanglement after UV- photodegradation. Scanning electron microscopy observations indicate that no crack and surface damage are observed, while the additional talc particles are exposed, on the UV-exposed surfaces. The exposure of talc particles may be responsible for the discoloration of UV-exposed polyolefin blend surface. Observation using Fourier transform infrared spectroscopy (FT-IR) confirms the presence of photodegradation on the surface of UV-exposed polyolefin blend.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.122-123
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• 1992

• Food Science and Preservation
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• v.8 no.4
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• pp.367-373
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• 2001

In order to study the effect of modified atmosphere storage on extending shelf life of King Oyster mushroom was wrapped with PVC film and packed with 20$\mu\textrm{m}$polyolefin(PD941), and effects of temperature(0, 5, 10$^{\circ}C$) in packaging conditions on the respiration and keeping qualities were evaluated. Higher respiratory activity and weight loss were observed at higher temperature. The concentration of O$_2$and CO$_2$ of PVC wrap and polyolefin(PD941) packages for all showed 1∼2% and 10∼14%, respectively. Polyolefin(PD941) package wan superior to the PVC wrap packaging method in Hardness, Hunter L value, Hunter b value and sensory qualities, and reducing weight loss at 0$^{\circ}C$, 5$^{\circ}C$ and 10$^{\circ}C$ compared to PVC wrap. It was found that the optimum shelf-life period of King Oyster mushroom packaged by PVC wrap was estimated to be 50, 28 and 12 days at 0, 5 and 10$^{\circ}C$, respectively, and 50, 32 and 21 days in Polyolefin(PD941).