Inline-Characterization of Bead Foam Extrusion Processing

与现有的可膨胀聚苯乙烯(EPS)和膨胀聚丙烯(EPP)的代表不同，大多数新的珠状泡沫不是通过悬浮或高压反应过程生产的，而是通过泡沫挤出和水下造粒相结合的方式连续生产的。这使得添加添加剂变得更容易。特别是化学改性(如CE=扩链剂)被用于研究和工业中，以增加工业热塑性塑料的熔体强度，这种熔体强度往往太低，不适合发泡。除了灵活性之外，众多的参数也增加了复杂性。此外，在与CE的熔体加工过程中，会发生反应过程，从而不断发生重大的材料性能变化。在处理大配方或热敏性材料时，某些最终性能的控制也同样复杂。来自系统和外围设备的大量数据已经被捕获用于监视；然而，没有进行永久性的、系统的记录和评估。此外，对该工艺进行科学评估所需的某些值是必要的，但有时根本不记录或仅部分记录(例如，熔体粘度、泡沫珠的粒度分布)。通过适当的在线分析，还可以提高数量和质量。附加功能是必要的，(I)实时收集所有与科学和技术相关的数据，(Ii)在运行过程中已经使用适当的数字方法对这些数据进行实时评估。这尤其包括最终产品的性质。理想情况下，可以识别以前未见过的工艺参数和材料参数之间的关系(例如，反应性、流变性和膨胀性的相关性)。此外，还可以建立一个数据基础，允许通过使用主动学习或机器学习对系统进行自我优化。通过建模，人们有望进一步了解和预测未知物质的行为。分析的质量也得到了提高，从在线流变学中可以明显看出：与离线测量(板材-板材)相比，这里测量的是与过程相关的(更高的)剪切速率，不再需要在准备和测量过程中重复熔融，这一点在化学修饰和热敏样品的情况下尤其关键。该系统概念独有地包含允许数字交换和记录和保存先前丢失的测量变量的组件。可以根据压力、流动行为、颗粒大小(分布)和工艺影响来跟踪材料的变化。因此，需要在线流变仪、附加的压力传感器、颗粒分析仪和合适的数字外围设备。

Unlike the established representatives of expandable polystyrene (EPS) and expandedPolypropylene (EPP) most new bead foams are not produced by suspension or in an autoclave process, but continuously by means of foam extrusion coupled to anunderwater granulation. This makes it easier to add additives. Especially thechemical modification (e.g., CE = chain extender) is used in research and industry to increase the melt strength of technical thermoplastics, which is often too low for foaming. In addition to the flexibility, the many parameters also increase the complexity. Furthermore, during the melt processing with the CE reactive processes occur and thus constantly significant material property change. The control of certain final properties is similarly complex when large formulations or thermally sensitive materials are processed. A lot of data from the system and the periphery is already being captured for surveillance; a permanent, systematic recording and evaluation however, does not take place. Furthermore, certain values which are necessary for a scientific evaluation of the process are necessary, but sometimes are not at all or only partially recorded (e.g., melt viscosity, size distribution of the foamed beads). Both quantity and quality can also be increased with appropriate inline analytics.The add-on is necessary (i) to collect all scientifically and technically relevant data in real time and (ii) to evaluate this data - with suitable digital methods - already in real time during the running process. This includes in particular the properties of the final products. Ideally, previously unseen relationships between process and material parameters can be recognized (e.g., correlation of reactivity, rheology and expansion). In addition, a data basis can be created which allows self-optimization of the system through the use of activelearning or machine learning. Through modelling further impulses for understanding and forecasting the behavior of unknown materials are expected. The quality of the analysis is also improved, as becomes evident from the inline rheology is: here, process-relevant (higher) shear rates are measured compared with offline measurement (plate-plate) and the repeated melting during preparation and measurement is no longer necessary, what is critical especially in the case of chemically modified and thermally sensitive samples. The system concept exclusively contains components that allows a digital exchange andrecord and save previously missing measured variables. Material changes can be traced based on pressures, flow behavior and particle sizes (distribution) and process influences. Therefor, an inline rheometer, additional pressure sensors, a particle analyzer and suitable digital peripherals are required.