• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.431-434
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• 2002

This paper reports on the evaluation of weathering resistance, tracking test and salt-fog of various kinds of cycloaliphatic epoxy systems. It was found that UV irradiation induced the loss of hydrophobic level due to the chain scission attack at the surface. It could be seen that samples containing an UV absorbent/antioxidant and a silicone oil additive knave a good performance in weathering ageing, whereas ATH filled ones have high resistance against tracking failure than others. Under salt-fog test, specimens mixed with silicone oil could suppress leakage current development. It was thought that silicone oil mixed into cycloaliphatic epoxy system could lead to lower the surface energy and to retain hydrophobic properties for a long time, which are desirable for outdoor performances.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1543-1545
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• 1997

In this work, properties of FRP insulation materials by thermal-accelerated degradation were investigated. Usually, most degradations cause the hydrophilic to decrease the contact angle and surface properties. But, in this work on thermal-degradated FRP, we can confirm the introduction of hydrophobic properties by cross-linking and the ablation of small-molecules rather than chain scission and oxidation. Hydrophobic introduction in thermal-degradated FRP caused the increase of electrical insulation on treated FRP surface. But, Tensile strength decreased steeply on FRP being exposed higher temperature.

• 대한화학회지
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• 제7권2호
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• pp.122-127
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• 1963

Pyrolysis fo polyethylene and polypropylene has been studied in order to clarify the mechanism of chain scission and effect of oxygen on degradation. Rate of weight decrease was measured under nitrogen and air atmosphere at constant temperature for the samples of high density polyethylene, low density polyethylene and isotactic polypropylene, and then gaseous hydrocarbons produced from pyrolysis were analysed by gas chromatography. Although there is little substantial difference between composition of hydrocarbon gases from pyrolysis of high density polyethylene and low density polyethylene except some difference in quantity of total gas produced, gas composition from polypropylene pyrolysis differs from that of polyethylene pyrolysis. Gases from pyrolysis under air contain much more unsaturated hydrocarbons than those from pyrolysis under inert gas.

• Elastomers and Composites
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• 제23권3호
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• pp.213-222
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• 1988

The thermal decomposition of poly(n-butyl methacrylate)(Pn-BMA) was studied using a dynamic and isothermal thermogravimetry in nitrogen gas with 50ml/min at several heating rates from 1 to $20^{\circ}C/min$, and at several heating temperature from 320 to $370^{\circ}C$. The mathematical techniques used for calculation of activation energy were Kissinger, Anderson, Chatterjee-Conrad, Friedman, Fuoss, Ozawa and isolthermal method. The range of activation energies obtained using the several techniques was between 43 and 51Kcal/mol except Chatterjee-Conrad and this range agreed with each other very well. The thermal degradation of Pn-BMA was considered to be carried out by main chain scission.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.430-433
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• 1999

MPPO(Modified-Polyphenylene Oxide) was irradiated with helium, nitrogen, and argon ions at the ion energy of 50 keV and 70 keV from the dose region of 5$\times$10$^{15}$ to 5$\times$10$^{16}$ ions/$\textrm{cm}^2$. The resistance of the irradiated MPPO surface could be decresed about 10$^{10}$ to 10$^{7}$ $\Omega$/sq with increasing the total ion dose and ion energy. Chemical characteristics of the irradiated surface were analyzed by XPS(X-ray photoelectron spectroscopy).

• 자연과학논문집
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• 제5권1호
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• pp.59-65
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• 1992

아실옥시이미노(AOI)기를 갖는 포리마의 광반응 특성을 검토한 결과, 포리마 주쇄의 구조에 따라 주반응이 다른것을 알았다. 아크릴타입(AAPO)포리마에서는 아미노기의 생성이 주 반응임에 반해 메타크릴타입(MAAPO)포리마에서는 주쇄절단반응과 이중결합 생성반응이 주 반응임을 알았다. 또한 본 연구에서는 광반응의 메카니즘을 정량분석을 통해 철저히 규명함과 아울러 이들 주 반응에서 생성된 아미노기와 주쇄절단반응을 이용한 기능성고분자에의 응용에 대해서도 연구 검토하였다.

• Elastomers and Composites
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• 제50권4호
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• pp.245-250
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• 2015

Recycling of ethylene-propylene-diene terpolymer (EPDM) scrap was tried by blending with polypropylene (PP). EPDM scrap powder was prepared by shear pulverization process at high temperature, which may lead to selective chain scission induced by difference in the critical elastic coefficient. On the other hand, EPDM scrap powder was prepared by adding a selected reclaiming agent during shear pulverization process at high temperature. Terpene as a bonding agent was then introduced to improve adhesion property. PP, used as a matrix for manufacturing thermoplastic elastomer, was modified by the incorporation of dicumyl peroxide and maleic anhydride. The functionalized EPDM and modified PP were blended and cured dynamically at $190^{\circ}C$. The blend materials prepared in this study showed the comparable results to those of conventional TPE in terms of tensile and flow properties. Also, the odor component of recycled EPDM was analyzed using GC-MS.

• Macromolecular Research
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• 제12권1호
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• pp.141-143
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• 2004

We have investigated the dynamic mechanical behavior of ultra-high molecular weight polyethylene (UHMWPE) irradiated with varying doses of gamma rays. A relaxation peak in the loss factor curve, which has not been reported previously in the literature, is observed at a temperature above the crystal melting temperature. The peak is unique to UHMWPE and appears to be related to the high degree of entanglement. Because the temperature and intensity of the peak are reduced by irradiation-induced chain scission and crosslinking, respectively, we believe that the peak is associated with disentanglement relaxation. The behavior of the storage modulus in the melt state agrees with the classical theory of rubber elasticity.

• Bulletin of the Korean Chemical Society
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• 제2권4호
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• pp.129-132
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• 1981

Polystyrene was degraded by using a vibrating ball mill. The viscosities and molecular weights of the degraded products were measured, and the decrease of viscosity $[\eta}$ with ${\dot{s}}$ (rate of shear) observed for the degraded products were analyzed by applying the Ree-Eyring equation for viscous flow. The variation of the parameters $x_2$/{\alhpa}_2,{\beta}_2$ and $x_1{\beta}_1/{\alpha}_1$ in the equation were explained by the fracture of polymer molecules by mechanical force. The electron paramagnetic resonance spectrum of the degraded sample was taken, and it was confirmed that free radicals were produced by the chain-scission of polystyrene.

• 폴리머
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• 제33권5호
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• pp.501-508
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• 2009

폴리감마글루탐산의 나트륨 염 (sodium salt of poly(${\gamma}$-glutamic acid))의 고체상과 용액상에서의 열분해 실험을 $57{\sim}120^{\circ}C$ 부근에서 실시하였고, 점성도법과 광산란법을 이용하여 분자량 감소 결과를 시간의 함수로 분석하였다. 고체상에서의 분해 결과는 사슬 절단 속도가 시간에 무관하게 일정하며, 사슬 내에서의 절단 위치 또한 무작위하다는 것을 보여주었다. 특히, 용액상에서의 시간에 따른 분해과정은 특성분해시간 $t^*$로 스케일링된 환산시간 $t/t^*$를 이용하여 분자량 또는 고유점성도를 도시할 경우 서로 다른 온도에서의 분해 과정은 하나의 표준곡선 위에 놓임을 알 수 있었다. 특히, 용액상에서의 분해곡선은 지수함수와 선형식의 합으로 표시할 수 있었으며 지수함수는 분해 초기에 뚜렷이 나타났다. 또한, 고체상 분해와 용액상 분해 모두 활성화 에너지는 $107{\sim}115$ kJ/mol로써 측정되었으며 문헌치와 좋은 일치를 보여준다.