Hallavant Kylian, Soccio Michelina, Guidotti Giulia, Lotti Nadia, Esposito Antonella, Saiter-Fourcin Allisson
INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux UMR 6634, University Rouen Normandie, F-76000 Rouen, France.
Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Via Terracini 28, 40131 Bologna, Italy.
Polymers (Basel). 2024 Oct 1;16(19):2792. doi: 10.3390/polym16192792.
Controlling the cooling rate experienced by a material during a manufacturing process is a challenge and a major issue. Industrial processing techniques are very diverse and may involve a whole range of cooling rates, which are sometimes extremely high for small and/or thin manufactured parts. For polymers, the cooling rate has consequences on both the microstructure and the time-dependent properties. The common cooling rates associated with conventional calorimetric measurements are generally limited to a few tens of degrees per minute. This work combines several calorimetric techniques (DSC, modulated-temperature DSC, stochastically-modulated DSC and Fast Scanning Calorimetry) to estimate the critical cooling rate required to melt-quench fast-crystallizing polyesters to their fully amorphous state, based on the example of a series of poly(alkylene -1,4-cyclohexanedicarboxylate) (PCHs) with a number of methylene groups in the main structure of the repeating unit nCH2 varying from 3 to 6. The even-numbered ones require faster cooling rates (about 3000 K s for nCH2 = 4, between 500 and 1000 K s for nCH2 = 6) compared to the odd-numbered ones (between 50 K min and 100 K s for nCH2 = 3, between 10 and 30 K min for nCH2 = 5).
在制造过程中控制材料所经历的冷却速率是一项挑战，也是一个重大问题。工业加工技术非常多样，可能涉及一系列冷却速率，对于小尺寸和/或薄型制造部件而言，这些冷却速率有时极高。对于聚合物，冷却速率对微观结构和随时间变化的性能都有影响。与传统量热测量相关的常见冷却速率通常限制在每分钟几十摄氏度。这项工作结合了多种量热技术（差示扫描量热法（DSC）、调制温度DSC、随机调制DSC和快速扫描量热法），以基于一系列聚（亚烷基-1,4-环己烷二甲酸酯）（PCHs）为例，估计将快速结晶聚酯熔体淬火至完全非晶态所需的临界冷却速率，其中重复单元nCH2主结构中的亚甲基数量从3变化到6。与奇数编号的聚酯（nCH2 = 3时为50 K/min至100 K/s，nCH2 = 5时为10至30 K/min）相比，偶数编号的聚酯需要更快的冷却速率（nCH2 = 4时约为3000 K/s，nCH2 = 6时为500至1000 K/s）。
