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第四届亚洲土工合成材料学术大会论文集 英文版_54.docx

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where RH is lhe polymer chain, hA is the photon energywith h and A, representing Planck's constant andwavelength, respectively, and R・,ROO・,RO* e OH*are lhe free radical species with R representing thepolymer chain. The oxidation reaction leads to chainscission in the polymer and yields a chemical product ofcarbonyl compound. The energy required to generate freeradicals in polyolefins is lower than that to break a bond;subsequently, polyolefins are more susceptible to UVdegradation than other types of polymers. Kay et al. 2004says that lhe energy carried by a monochromatic ray isinversely proportional to its wavelength. The shorter thewavelength, the higher the potency of bonds cleavage (Fig.I).Fig. 1Photon energy versus wavelength (Kay et al. 2004)The ASTM D5970 procedure is commonly used like aguide in outdoor exposure to evaluate geotextile products.This method only evaluates ultraviolet degradation at aspecific site in terms of expected life, not in terms ofincident radiation and temperature. This test methodevaluates geotextiles under site specific atmospheric
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Term
Summer
Professor
Eric Larson
Tags
Polymer, Energy, Ultraviolet

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