• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.473-476
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• 2004

This study has investigated radiation degradation of low density polyethylene(LDPE). Samples were irradiated using a $Co^{60}\;\gamma-ray$ and ray up to 800 kGy at a dose rate of 5 kGy/hr in the presence of air atmosphere at room temperature. After irradiation, free radical measurement of LDPE has established by electron spin resonance(ESR). Then, each sample was stored for 2 weeks. ESR measurement showed that free radical concentration(FRC) was increased with radiation dose and changed from alkyl, allyl radical to peroxy radical with time.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1174-1176
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• 1993

Morphology of low density polyethylene(LDPE) such as the degree of crystallinity changes with thermal history etc. In order to clarify the effects of morphological changes on electrical breakdown, we studied direct current and impulse breakdown phenomena of LDPE films heat-treated at 100[$^{\circ}C$] for 1[H] in silicone oil and subsequently cooling to various ways. The degree of crystallinity was estimated by the infra red absorption and X-ray diffraction measurements for the specimens of slowly cooled, cooled in water, original, and cooled in liquid nitrogen gas. As the result, we obtained that the first, second, third, and fourth was slowly cooled of 70.23[%], cooled in water of 61.6[%], original specimen of 56.75[%], and cooled in liquid nitrogen gas of 34.7[%] respectively. The crystalline size and distribution of specimens were researched by Differential scanning calolimeter measurements.

• Journal of Bio-Environment Control
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• v.24 no.2
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• pp.79-84
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• 2015

This study was carried out in order to develop an economical and convenient way to improve storability of sweet persimmon 'Fuyu'. Natural porous materials (bamboo active carbon, chaff charcoal, and Ge-lite) pouching bags were enveloped in the conventional LDPE (low density polyethylene) package during room temperature and low temperature storage. The changes of soluble solids content, flesh firmness, flavor, decay, and softening of sweet persimmon were investigated in the 1- or 2-week intervals. The LDPE packaging with bamboo active carbon treatment was confirmed to maintain longer storability and higher quality than the LDPE packaging only. This method is expected to be applied to both of conventional and organic farming as an economical and convenient way to improve storability on long term storage and during distribution.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.477-482
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• 2008

A variety of bacterial strains were isolated from waste disposal sites of Uttaranchal, India, and some from artificially developed soil beds containing maleic anhydride, glucose, and small pieces of polyethylene. Primary screening of isolates was done based on their ability to utilize high- and low-density polyethylenes (HDPE/LDPE) as a primary carbon source. Thereafter, a consortium was developed using potential strains. Furthermore, a biodegradation assay was carried out in 500-ml flasks containing minimal broth (250ml) and HDPE/LDPE at 5mg/ml concentration. After incubation for two weeks, degraded samples were recovered through filtration and subsequent evaporation. Fourier transform infrared spectroscopy (FTIR) and simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) were used to analyze these samples. Results showed that consortium-treated HDPE (considered to be more inert relative to LDPE) was degraded to a greater extent (22.41% weight loss) in comparison with LDPE (21.70% weight loss), whereas, in the case of untreated samples, weight loss was more for LDPE than HDPE (4.5% and 2.5%, respectively) at $400^{\circ}C$. Therefore, this study suggests that polyethylene could be degraded by utilizing microbial consortia in an eco-friendly manner.

• Korea-Australia Rheology Journal
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• v.14 no.1
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• pp.25-32
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• 2002

We report the first steps of a collaborative project between the University of Queensland, Polyflow, Michelin, SK Chemicals, and RMIT University, on simulation, validation and application of a recently introduced constitutive model designed to describe branched polymers. Whereas much progress has been made on predicting the complex flow behaviour of many - in particular linear - polymers, it sometimes appears difficult to predict simultaneously shear thinning and extensional strain hardening behaviour using traditional constitutive models. Recently a new viscoelastic model based on molecular topology, was proposed by McLeish and carson (1998). We explore the predictive power of a differential multi-mode version of the porn-pom model for the flow behaviour of two commercial polymer melts: a (long-chain branched) low-density polyethylene (LDPE) and a (linear) high-density polyethylene (HDPE). The model responses are compared to elongational recovery experiments published by Langouche and Debbaut (19c99), and start-up of simple shear flow, stress relaxation after simple and reverse step strain experiments carried out in our laboratory.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1661-1663
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• 2004

The effect of the triblock copolymer poly[styrene-b-(ethylene-co-butylene)-b-styrene](SEBS) on the formation of space charge of immiscible low density polyethylene/polystyrene(LDPE/PS) blends was investigated. The amount of charge accumulated in the 70/30(wt%) LDPE/PS blends decreased when the SEBS content increased up to 10 wt%. For compatibilzed and uncompatibilized blend, morphological observation showed that the addition of SEBS results in the domain size reduction of the dispersed PS phase and a better interfacial adhesion between LDPE and PS phases. The location of SEBS at a domain interface enables charges to migrate from one phase to the other via domain interface and therefore, results in a significant decrease in the amount of space charge for the LDPE/PS blends with SEBS.

• Journal of Microbiology and Biotechnology
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• v.20 no.5
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• pp.908-916
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• 2010

Fullerene-60 nanoparticles were used for studying their effect on the low-density polyethylene (LDPE) biodegradation efficiency of two potential polymer-degrading consortia comprising three bacterial strains each. At a concentration of 0.01% (w/v) in minimal broth lacking dextrose, fullerene did not have any negative influence upon the consortia growth. However, fullerene was found to be detrimental for bacterial growth at higher concentrations (viz., 0.25%, 0.5%, and 1%). Although addition of 0.01% fullerene into the biodegradation assays containing 5mg/ml LDPE subsided growth curves significantly, subsequent analysis of the degraded products revealed an enhanced biodegradation. Fourier transform infrared spectroscopy (FT-IR) revealed breakage and formation of chemical bonds along with the introduction of ${\nu}C$-O frequencies into the hydrocarbon backbone of LDPE. Moreover, simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) revealed a higher number of decomposition steps along with a 1,000-fold decrease in the heat of reactions (${\Delta}H$) in fullerene-assisted biodegraded LDPE, suggesting the probable formation of multiple macromolecular byproducts. This is the first report whereby fullerene-60, which is otherwise considered toxic, has helped to accelerate the polymer biodegradation process of bacterial consortia.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1481-1483
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• 1998

we have investigated the effect of aromatic compounds and tree inception and growth in low density polyethylene, for AC voltage and Impulse voltage. 2kinds of aromatic compounds are selected. Each additive (m-cresol, aniline) was mixed in low density polyethylene. For AC voltage, 10wt% $\sim$ 15wt% m-cresol can be shown to be the effective inhibitor to tree initiation. But, For Impulse voltage, 10wt% $\sim$ 15wt% aniline is effective inhibitor to tree initiation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.82-85
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• 1996

It is considered that the effect of radiation aging, such as electron beam due to the ultra-high voltage for transmission, on the physical properties and electrical characteristics of electrital insulating materials. Low-density polyethylene(thickness 100[${\mu}{\textrm}{m}$]) is selected as an experimental specimen. Fourier transform infra-red spectrum, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy is used so as to analysis the physical properties, the morphological changes and the crystallinity of LDPE. And it is made an experiments of dielectric characteristics in the temperature range of 20[$^{\circ}C$]~120[$^{\circ}C$], in the frequency range of 30[Hz]~1.5$\times$10$^{5}$ [Hz] and in the applied voltage range of 300[mV]~1500[mV].

• Clean Technology
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• v.5 no.2
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• pp.45-52
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• 1999

Recycling of red mud from the aluminium manufacturing process was investigated to be utilized as plastic fillers. High density polyethylene(HDPE), low density polyethylene(LDPE) and polypropylene(PP) were found to be the suitable plastic material for which red mud can be used as fillers. With the addition of red mud the plastic showed red brown color. As the ratio of amount of red mud to plastic increased, the tensile strength increased while the Izod impact strength decreased. About five percent of ethylene vinyl alcohol(EVA) was needed as an additive to prevent the lowering of impact strength. Maleic anhydride modified polypropylene was effective for reduction of impact strength lowering of PP. Mixed waste plastics containing LDPE, HDPE, PP, polystyrene and ABS could also accommodate red mud as fillers. In this case, significant loss in mechanical properties were observed due to immiscibility between the components. Ethylene propylene rubber(EPR) and styrene butadiene styrene block copolymer (SBS) could be used to improve the impact properties of the commingled waste plastics.