Integration of flexible capacitive sensors in polymers for monitoring of polymerization and degradation processes.

在线过程监测（OPM）通过减少加工时间和成本，同时提高质量，有可能扩大纤维增强聚合物的应用领域。监测固结过程，特别是固化过程是很重要的，因为它并不总是均匀的在整个制造部分。因此，传感器应集成在材料中，以监测层压板内部的制造过程。因此，传感器必须承受制造过程，并且不影响所生产部件的功能。为了实现这一目标，在“聚合物中用于聚合和降解监测的柔性电容传感器集成”项目中开发了一种小型化的柔性介电传感器。传感器被嵌入到碳纤维增强热固性聚合物中，并成功地监测了固化过程。此外，还研究了传感器对生产零件机械完整性的影响。准静态测试表明，传感器不会显著降低材料的机械性能。在本项目范围内，研究了热固性材料作为基体材料的固化。除热固性塑料外，热塑性塑料还用于纤维增强聚合物的生产。热塑性塑料的优点是生产过程可以大大加快。工业应用方面的一个重要考虑因素是，使用热塑性塑料可以减少制造周期时间。此外，它们可以重熔，这允许修复和回收缺陷部件。在热固性聚合物的固化过程中，会产生交联和共价键。相反，热塑性塑料的聚合物链不能交联，但它们可以彼此对齐。排列区和非晶态区之间的比率称为结晶度。这个度数决定了材料的机械和热性能，可以通过改变工艺参数来调节。因此，在纤维增强聚合物的制备过程中，应利用介电传感器和光纤在线测量其结晶程度。该项目的目标是在纤维增强塑料复合材料的制造过程中监测热塑性塑料的结晶，特别是尽可能精确地测量和控制结晶程度和载荷转移点，以确定材料内部的凝固点。为了覆盖更广泛的电磁频谱，与小型化的介电传感器并行，还应嵌入光纤传感器。两种度量原则的结合显著地增加了信息量，这有助于为过程的评估确定合适的模型。

Online-Process-Monitoring (OPM) has the potential to extend the area of application of fibre reinforced polymers by reducing processing times and costs while increasing the quality. It is important to monitor the consolidation process, especially the curing process, since it is not always homogenous in the whole fabricated part. Therefore, sensors should be integrated in the material to monitor the fabrication process inside the laminate. Hence, it is necessary that the sensors withstand the fabrication process and do not influence the functionality of the produced part. To fulfil this goal, a miniaturized flexible dielectric sensor was developed within the project “Integration of Flexible Capacitive Sensors in Polymers for Polymerization and Degradation Monitoring”. The sensors were embedded in carbon fibre reinforced thermosetting polymers and the curing process was successfully monitored. Furthermore, the influence of the sensor on the mechanical integrity of the produced part was investigated. Quasistatic tests were used to demonstrate that the sensor does not significantly degrade the mechanical properties of the material. Within the scope of this project, the curing of thermosets as matrix material was investigated. Beside thermosets, thermoplastics are used in the fibre reinforced polymer production. Thermoplastics have the advantage that the production process can be considerably faster. One important consideration in terms of industrial application is that it is possible to reduce the manufacturing cycle time by using thermoplastics. Furthermore they can be remelted, which allows for repairing and recycling defect parts. During the curing process of thermosets, the polymer chains crosslink and covalent bonds are created. On the contrary, the polymer chains of thermoplastics do not crosslink but they can be aligned to each other. The ratio between aligned and amorphous regions is called degree of crystallization. This degree determines the mechanical and thermal properties of the material and can be adjusted by varying the process parameters. Therefore, the degree of crystallization should be measured online during the fabrication process of the fibre reinforced polymers using dielectric sensors and optical fibres.The goal of the project is to monitor the crystallization of thermoplastics during the fabrication process of fibre reinforced plastic composites, especially to measure and control as accurate as possible the degree of crystallization and the load transfer point to determine the solidification point inside the material.In parallel to the miniaturized dielectric sensors, optical fibre sensors should also be embedded in order to cover a broader electromagnetic spectrum. The combination of both measurement principles increases the amount of information significantly, which helps determining a suitable model for the evaluation of the process.