• Macromolecular Research
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• 제17권8호
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• pp.580-584
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• 2009

The effects of crystallinity and radiation crosslinking on the physical properties of a microporous high density polyethylene (HDPE) film with Millad3988 as a nucleating agent were investigated. The pores of the HDPE film were affected by the crystallinity. The crystallinity of the HDPE films increased with increasing Millad3988 amount up to 0.1 wt% but decreased with further addition. The mechanical characteristics of the HDPE containing Millad3988 films improved with increasing irradiation dose up to 50 kGy, but decreased at 75 kGy due to severe degradation. The thermal shrinkage behavior of the HDPE films decreased with increasing radiation dose up to 50 kGy. The porosity of the stretched HDPEIMillad3988 films after ${\gamma}$-ray radiation increased with increasing y-ray radiation dose up to 50 kGy. The pores of the irradiated films were formed more easily by a stretching due to the formation of a crosslinked structure.

• 방사선산업학회지
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• 제18권3호
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• pp.227-233
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• 2024

Polyolefins (PO) are used in various industrial fields due to their excellent mechanical properties, processability, and chemical resistance. However, they have low flame retardancy, and when exposed to high temperatures, there are problem that mechanical properties deteriorate due to oxidation. In this study, we developed PO/metal hydroxide composites that exhibit excellent mechanical strength, heat resistance, and flame retardancy by using antioxidants and radiation crosslinking technology. To improve mechanical strength, heat resistance, and flame retardancy, PO/metal hydroxide/antioxidant composites were prepared and irradiated with an electron beam. Specifically, at temperatures above 200℃, the PO/metal hydroxide composites with primary and secondary antioxidants added and irradiated with a 100 kGy electron beam exhibited excellent thermal stability with a thermal shrinkage rate of less than 3%. In addition, the flame retardancy of the PO/metal hydroxide/antioxidant composites was improved due to enhanced thermal stability from electron beam irradiation and reduced thermal decomposition rate from the antioxidants. These results indicate that radiation crosslinking and antioxidants are effective method to simultaneously achieve mechanical properties, heat resistance, and flame retardancy.

• 한국전기전자재료학회논문지
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• 제31권2호
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• pp.107-111
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• 2018

In this study, we designed the temperature coefficient of resistance (TCR) and heat radiation properties of shunt fixed resistors by adjusting the atomic composition of a metal alloy resistor, and fabricated a resistor that satisfied the designed properties. Resistors with similar atomic composition of copper and nickel showed low TCR and excellent shunt fixed resistor properties such as short-time overload, rated load, humidity load, and high temperature load. Finally, we expect that improved sensor accuracy will be obtained in current-distribution-type shunt fixed resistor for IoT sensors by designing the atomic composition of the metal alloy resistor proposed in this work.

• 한국안전학회지
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• 제21권4호
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• pp.55-59
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• 2006

The radiation effects on electrical and mechanical properties of LDPE/EVA blends with various vinyl acetate contents were investigated. Radiation degradation of LDPE/EVA blends were studied by using gelation, volume resistivity, permittivity, dissipation factor, elongation at break, and E-modulus. As vinyl acetate contents increased in LDPE/EVA blends, electrical insulation characteristics were deteriorated, but flexibility was improved. As irradiation doses increased, electrical insulation characteristics were improved, but flexibility was deteriorated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1537-1539
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• 2001

The radiation degradation of five insulating materials such as silicone rubber, ethylene-propylene rubber polybutylene terephthalte, poly carbonate, nylon 66 were evaluated by using thermogravimetry analysis (TGA) and tensile properties as a function of radiation doses. The results of temperature at 5% weight loss and activation energy from TGA showed linearly decreasing and increasing tendency as radiation doses comparing with tensile properties. Consequently, the assessment of TGA for the radiation degradation of materials was effective.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.485-488
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• 2003

Radiation degradation of Poly(ether ether ketone) (PEEK) has been studied by dielectric analysis and dynamic mechanical analysis. It has been observed that dielectric properties are influenced by radiation degradation of PEEK. For radiation degradation of PEEK, dynamic mechanical properties were insensible.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.457-460
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• 2004

Many of the physical and chemical properties of polymer materials can be altered by high energy radiation. In the present work the exposure to radiation of low density polyethylene(LDPE) included antioxidants was carried out at various doses up to 600kGy at a dose rate of 5kGy/hr in the presence of air at room temperature. The study of the irradiation effects on the material properties has been make by different methods in an integrated way. The experimental data indicate that the decomposition onset temperature(DOT), the crystallinity and the thermoluminescence(TL) with radiation dose. DOT, crystallinity and TL analysis from irradiated PE samples provides useful data for the characterization of radiation-induced oxidation effects on these samples.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.252-253
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• 2005

The dielectric relaxation properties of $^{60}Co$ gamma-ray irradiated Poly(vinylidene fluoride) (PVDF) containing various antioxidants have been investigated for radiation degradation. Cole-Cole's circular arcs were induced from the results of temperature and frequency dependency of dielectric properties with radiation dose. The magnitude of polarization of PVDF was decreased by adding antioxidants. The values of dielectric relaxation intensity calculated by using the Cole-Cole's circular arcs showed a certain tendency for radiation degradation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.894-896
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• 2001

The Polypropylene films which are made by refinement of its pellet and formed as crystals are exposed to Radiation. As the results, degradation effects were observed in non-crystalline regions. It is thus considered that the effects occur by destroying of lattice binding force by Radiation. The distribution of degradation was increased with irradiation quantities of Radiation and dielectric constant of Polypropylene sheets irradiated Radiation was rapidly increased from above 10 MHz.

• 한국의학물리학회지:의학물리
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• 제32권4호
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• pp.159-164
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• 2021

Purpose: We investigated the properties of CLEANBOLUS based on silicone with suitable characteristics for clinical use. Methods: We evaluated the characteristics of CLEANBOLUS and compared the results with the commercial product (Super-Flex bolus). Also, we conducted physical evaluations, including shore hardness, element composition, and elongation break. Transparency was investigated through the measured absorbance within the visible region (400-700 nm). Also, dosimetric characteristics were investigated with surface dose and beam quality. Finally, the volume of unwanted air gap was investigated based on computed tomography images for breast, chin, and nose using Super-Flex bolus and CELANBOLUS. Results: CLEANBOLUS showed excellent physical properties for a low shore hardness (000-35) and elongation break (>1,000%). Additionally, it was shown that CLEANBOLUS is more transparent than Super-Flex bolus. Dosimetric results obtained through measurement and calculation have an electron density similar to water in CLEANBOLUS. Finally, CLEANBOLUS showed that the volume of unwanted air gap between the phantom and each bolus is smaller than Super-Flex bolus for breast, chin, and nose. Conclusions: The physical properties of CLEANBOLUS, including excellent adhesive strength and lower shore hardness, reduce unwanted air gaps and ensure accurate dose distribution. Therefore, it would be an alternative to other boluses, thus improving clinical use efficiency.