Dielectric studies of PVDF crystallization. Application to in-situ monitoring in injection molding
Dielectric studies of PVDF crystallization. Application to in-situ monitoring in injection molding
复制标题
PVDF 结晶的介电研究。
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
G. Seytre
中科院分区：
文献类型：
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作者：
J. Gonnet;J. Guillet;G. Boiteux;R. Fulchiron;G. Seytre
近年来，基于微介电测量的实验技术已经提出了一个有吸引力的和越来越多的兴趣，连续监测在固化下的热固性树脂反应的进展的无损方式。这种技术的一个新的应用已经进行了原位监测热塑性结晶。因此，一个动态流变仪配备了一个介电池，以及一个仪器化的狭缝模具，设计。的结晶过程中描绘的电导率下降，以及通过在真实的介电常数的最大值的发生。比电导率的降低是由于导电路径的改变，而介电常数的增加是由于非晶相和生长的结晶实体之间的界面极化现象。作为发展的第二步，微介电测量已被应用于在注塑过程中的热塑性塑料的结晶的原位监测。电传感器位于模腔的壁上，以便可以进行填充、填充后和冷却阶段期间的体介电性质的分析。本文详细描述的介电方法提供了一种新的非侵入性技术，并且可以应用于注射成型过程的闭环控制。
In recent years, experimental techniques based on microdielectrometry have presented an attractive and increasing interest for continuous monitoring in a nondestructive way of the advancement of thermoset resin reactions under cure. A new application of this technique has been carried out also for in situ monitoring of thermoplastic crystallization. Therefore, a dynamic rheometer equipped with a dielectric cell, as well as an instrumented slit die, were designed. The crystallization process is depicted by a conductivity drop as well as by the occurrence of a maximum in the real permittivity. The decrease of the specific conductivity results from a modification of the conductive paths whereas the increase in permittivity is due to an interfacial polarization phenomenon between the amorphous phase and the growing crystalline entities. As a second step of development, microdielectrometry has been applied for in situ monitoring of the crystallization of thermoplastics during an injection molding process. The electric sensors were located at the walls of the mold cavity so that an analysis of bulk dielectric properties during the filling, post-filling and the cooling phases could be performed. The dielectric method detailed herein provides a new non-invasive technique and could be applied to a closed-loop control of the injection molding process.