The effect of ultraviolet radiation on ultrasonic properties of polyurea
The effect of ultraviolet radiation on ultrasonic properties of polyurea
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DOI：
10.1016/j.polymdegradstab.2015.11.009
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发表时间：
2016
影响因子：
5.9
通讯作者：
Ian Whitten;G. Youssef
中科院分区：
文献类型：
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作者：
Ian Whitten;G. Youssef
聚脲用于军事和民用应用中，其中暴露于太阳通常是长时间的，这会使其机械性能劣化到次优水平。本研究报告的聚脲作为紫外线照射时间和温度的函数的超声波性能。六组样品连续暴露于紫外线辐射不同的持续时间长达15周。还测试了未接受UV暴露的对照样品。超声特性的测量使用高频接触超声换能器在一发一收配置。所有暴露样品均显示出从透明黄色至不透明浅棕色的显著颜色变化。早在紫外线照射3周时就观察到颜色的变化。尽管如此，仅在连续暴露6、9、12和15周的样品中观察到银纹。随着暴露持续时间的延长，表面裂纹的尺寸增加。延长紫外线辐射对声学性能的影响被认为是最小的，其中弹性模量和剪切模量单调下降后，在最初的增加，在前3周的曝光。在23 °C和40 °C下测量衰减特性。P波衰减没有表现出任何显著的变化，而S波衰减随着温度和UV暴露时间的增加而单调下降。
Polyurea is used in military and civilian applications where exposure to the sun is commonly of long duration, which can deteriorate its mechanical performance to suboptimal levels. This study reports on the ultrasonic properties of polyurea as a function of ultraviolet radiation exposure duration and temperature. Six sets of samples were continuously exposed to ultraviolet radiation for different durations up to 15 weeks. Control samples were also tested that did not receive UV exposure. The ultrasonic properties were measured using high-frequency contact ultrasound transducers in pitch-catch configuration. All exposed samples exhibited significant color changes from transparent yellow to opaque light brown. Changes of color were observed as early as 3 weeks of UV exposure. Nonetheless, crazing was only observed in samples of 6, 9, 12, and 15 weeks of continuous exposure. The size of the surface cracks increased as the duration of exposure continued. The effect of extended UV radiation on the acoustic properties was noted to be minimal, where elastic and shear moduli decreased monotonically after an initial increase during the first 3 weeks of exposure. The attenuation properties were measured at 23 °C and 40 °C. The p-wave attenuation did not show any notable change, while the s-wave attenuation monotonically decreased as the temperature and UV exposure duration increased.