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Analysis of Solvent Effect on Mechanical Properties of Poly(ether ether ketone) Using Nano-indentation
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作者 Tanveer Iqbal Saima Yasin +3 位作者 ahmad shakeel Hamayoun Mahmood Fahad Nazir Paul F. Luckham 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2018年第2期211-215,246,共6页
Poly(ether ether ketone) (PEEK) is a high-performance semi-crystalline thermoplastic polymer. Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or ... Poly(ether ether ketone) (PEEK) is a high-performance semi-crystalline thermoplastic polymer. Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or dissolution. In this study, nano-indentation analysis was performed to study the effect of acetone on the surface mechanical properties of PEEK using different exposure time. The experiments were performed with a constant loading rate (10 nrn/s) to a maximum indentation displacernent (1000 nrn). A 30-second hold segrnent was included at the maximum load to account for any creep eft)ors followed by an unloading segrnent to 80% unloading. The indentation hardness and the elastic modulus were corn- puted as a continuous function of the penetration displacernent in the continuous stiffness mode (CSM) indentation. The experirnental data showed that the peak load decreased from -5.2 mN to -1.7 mN as exposure tirne in solvent environrnent increased from 0 to 18 days. The elastic modulus and the hardness of PEEK samples also displayed a decreasing trend as a function of exposure tirne in the solvent environrnent. Two empirical models were used to fit the experirnental data of hardness as a function of exposure tirne which showed a good agreernent with the experirnental values. 展开更多
关键词 SOLVENT Nano-indentation Poly(ether ether ketone) MODULUS HARDNESS
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降雨特征对多雨城市海绵改造小区径流控制效果的影响 被引量:13
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作者 印定坤 陈正侠 +4 位作者 李骐安 贾海峰 刘正权 沈雷 ahmad shakeel 《清华大学学报(自然科学版)》 EI CAS CSCD 北大核心 2021年第1期50-56,共7页
为科学定量评价不同降雨特征对多雨城市海绵改造小区径流控制效果的影响,该文基于在线监测和模型模拟相结合的方法,以某多雨地区海绵城市试点区内一个典型小区为研究对象,布置代表性的监测点对其排口流量和悬浮物(suspended solid,SS)... 为科学定量评价不同降雨特征对多雨城市海绵改造小区径流控制效果的影响,该文基于在线监测和模型模拟相结合的方法,以某多雨地区海绵城市试点区内一个典型小区为研究对象,布置代表性的监测点对其排口流量和悬浮物(suspended solid,SS)进行连续在线监测。在此基础上构建暴雨洪水管理模型(storm water management model,SWMM),开展海绵小区改造对径流水量控制和水质净化效果评价的实证研究。利用实测在线降雨水量水质数据对模型关键参数进行率定和验证,Nash-Sutcliffe效率系数均大于0.71。在实际场次降雨和典型年降雨情景下,模拟分析了海绵改造对雨水径流水量控制和水质净化的效果。结果表明,海绵改造后,小区范围内的年径流总量控制率为52.9%,年径流削减率为28.0%,污染物负荷削减率为66.3%。整体而言,共计81场降雨事件下的径流控制率均达到70%以上。同时,研究发现极端降雨事件与各降雨事件下的降雨特征均对场降雨径流控制能力有不同程度的影响。研究区2009年内平均场降雨控制率为86.5%,而当分别不考虑极端小降雨/暴雨事件时,平均场降雨控制率为79.9%和88.2%。降雨量与雨前干期对场降雨径流控制能力的影响较大,在小雨(<15 mm)、中雨(10~25 mm)及大雨(>25 mm)3种不同情况下,研究区的场降雨径流平均控制率分别为98.1%、73.8%和52.9%。在雨前干期大于等于6 d的降雨事件下(共15场),场降雨径流控制率均达到90%以上。而降雨历时与平均雨强对场降雨径流控制率的影响并不显著。 展开更多
关键词 排水工程 海绵城市 在线监测 暴雨洪水管理模型(SWMM) 小区尺度 水量控制 污染物去除 降雨特征
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