Developments in new sensor technologies and data processing are helping to increase the number of applications of nondestructive characterization methods. In this study, two major physiochemical phenomena affecting product quality of rotationally molded polyethylene parts, namely sintering and degradation, were evaluated using both traditional characterization techniques and a newer alternative ultrasonic-based method. Oven temperature and heating cycle time were controlled to produce six different process conditions for rotomolding. Increasing peak internal air temperature (PIAT) inside the mold produced a reduction in surface voids (pitting) and increased the impact strength for produced parts, which can be related to greater densification during sintering. Contrary to these characterizations denoting improved part quality, degradation was detected for PIAT above 220 °C by an increase in surface carbonyl groups by Fourier-transform infrared spectroscopy (FT-IR) and an increase in zero-shear viscosity, both relatable to thermo-oxidative free radical reactions. The newly proposed monitoring technique applying propagating ultrasonic guided waves showed that its data-rich spectral features based on harmonic frequencies were positively correlated to the same sintering and degradation properties observed above. Coupled with multivariate statistical analysis, the nondestructive ultrasonic technique shows great promise for combining multiple analyses in a single sensor technology, making it well suited to the implementation of advanced manufacturing methodologies in polymer processing practices.

新传感器技术和数据处理的发展正在帮助增加无损表征方法的应用数量。在这项研究中，使用传统的表征技术和更新的基于超声波的方法对影响旋转模塑聚乙烯零件产品质量的两个主要物理化学现象（即烧结和降解）进行了评估。控制烤箱温度和加热循环时间以产生用于滚塑的六个不同工艺条件。模具内部最高峰值内部空气温度（PIAT）升高，可减少表面空隙（点蚀）并提高所生产零件的冲击强度，这可能与烧结过程中的致密化程度更高有关。与这些表征零件质量改善的特征相反，对于220°C以上的PIAT，通过傅立叶变换红外光谱（FT-IR）表面羰基的增加和零剪切粘度的增加检测到了PIAT的降解，这都与热氧化自由基反应有关。最新提出的使用传播的超声波导波的监测技术表明，其基于谐波频率的数据丰富的光谱特征与上述观察到的相同烧结和降解性能呈正相关。与多变量统计分析相结合，无损超声技术显示了将多种分析合并到一个传感器技术中的巨大希望，使其非常适合在聚合物加工实践中实施先进的制造方法。