Billon Noëlle, Castellani Romain, Bouvard Jean-Luc, Rival Guilhem
Mines Paris, PSL University, Centre for Material Forming (CEMEF), UMR CNRS 7635, 06904 Sophia Antipolis, France.
Lyon University, INSA-Lyon, LGEF, EA682, 69621 Villeurbanne, France.
Polymers (Basel). 2023 Sep 21;15(18):3846. doi: 10.3390/polym15183846.
This paper deals with the viscoelastic behavior during crystallization and melting of semicrystalline polymers, with the aim of later modeling the residual stresses after processing in cases where crystallization occurs in quasi-static conditions (in additive manufacturing for example). Despite an abundant literature on polymer crystallization, the current state of scientific knowledge does not yet allow ab initio modeling. Therefore, an alternative and pragmatic way has been explored to propose a first approximation of the impact of crystallization and melting on the storage and loss moduli during crystallization-melting-crystallization cycles. An experimental approach, combining DSC, optical microscopy and oscillatory shear rheology, was used to define macroscopic parameters related to the microstructure. These parameters have been integrated into a phenomenological model. Isothermal measurements were used to describe the general framework, and crystallization at a constant cooling rate was used to evaluate the feasibility of a general approach. It can be concluded that relying solely on the crystalline fraction is inadequate to model the rheology. Instead, accounting for the microstructure at the spherulitic level could be more useful. Additionally, the results obtained from the experiments help to enhance our understanding of the correlations between crystallization kinetics and its mechanical effects.
本文研究了半结晶聚合物结晶和熔融过程中的粘弹性行为，目的是后续对准静态条件下（例如增材制造中）发生结晶的加工后残余应力进行建模。尽管关于聚合物结晶的文献丰富，但目前的科学知识水平尚无法进行从头建模。因此，探索了一种替代且务实的方法，以提出结晶和熔融对结晶 - 熔融 - 结晶循环中储能模量和损耗模量影响的一阶近似。采用结合差示扫描量热法（DSC）、光学显微镜和振荡剪切流变学的实验方法来定义与微观结构相关的宏观参数。这些参数已被纳入一个唯象模型。等温测量用于描述总体框架，以恒定冷却速率结晶用于评估通用方法的可行性。可以得出结论，仅依靠结晶分数来对流变学进行建模是不够的。相反，考虑球晶水平的微观结构可能更有用。此外，实验获得的结果有助于增强我们对结晶动力学及其力学效应之间相关性的理解。
