Real‐time ultrasonic characterization of the chain orientation of high density polyethylene melts during processing
Real‐time ultrasonic characterization of the chain orientation of high density polyethylene melts during processing
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DOI：
10.1002/pen.21634
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发表时间：
2010-06
影响因子：
3.2
通讯作者：
Congmei Lin;Shanshan Wang;Huimin Sun;Jiang Li;Shaoyun Guo
中科院分区：
文献类型：
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作者：
Congmei Lin;Shanshan Wang;Huimin Sun;Jiang Li;Shaoyun Guo
为了了解加工过程中超声波信号的演变与分子结构变化之间的关系，使用非侵入性和非破坏性超声波技术研究了不同熔融指数的高密度聚乙烯（HDPE）熔体的剪切引起的链取向及其随后的定向混乱。这些熔体定向和定向混乱过程中分子结构的发展体现在超声波速度中。开发了两个模型来分别描述定向和定向障碍的松弛过程。还探讨了剪切速率和温度对最大取向度以及取向和失取向弛豫时间的影响。将超声波测量的这些结果与通过流变测量、X 射线衍射 (XRD) 和红外二色性测量获得的结果进行比较。实验结果表明，超声波技术对于实时监测聚合物加工过程中分子结构的演变具有灵敏性和应用前景。聚合物。 ENG。 SCI.，2010。© 2009 塑料工程师学会
In an attempt to understand the relationships between the evolution of ultrasonic signal and the change of molecular structure during processing, shear-induced chain orientation and its subsequent disorientation of high-density polyethylene (HDPE) melts with different melt indices were studied using a noninvasive and nondestructive ultrasonic technique. The molecular structural development during orientation and disorientation of these melts was manifested in the ultrasonic velocity. Two models were developed to describe the relaxation processes of orientation and disorientation, respectively. The effects of shear rate and temperature on the maximal degree of orientation and the relaxation time of orientation and disorientation were also explored. These results from the ultrasonic measurements were compared with ones obtained through rheological measurements, X-ray diffraction (XRD), and infrared dichroism measurements. The experimental results indicated that the ultrasonic technique was sensitive and promising for the real-time monitoring of the evolution of molecular structure during polymer processing. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers