Modeling of the polymerization and crystallization kinetic coupling of polyamide 6 synthesized from ε-caprolactam

Vicard, Céline; Almeida, Olivier de; Cantarel, Arthur; Bernhart, Gérard

doi:10.1016/j.polymer.2019.121681

Cited by 10 publications

(28 citation statements)

References 55 publications

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“…The materials produced through T-RTM could be cheaper, safer and more recyclable, and in addition, they should be produced relatively fast due to their quick chemical reaction polymerization. So far, this quick reaction has been very difficult to control and model [11,12].…”

Section: Introductionmentioning

confidence: 99%

Nucleation and Crystallization of PA6 Composites Prepared by T-RTM: Effects of Carbon and Glass Fiber Loading

et al. 2019

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Thermoplastic resin transfer molding (T-RTM) is attracting much attention due to the need for recyclable alternatives to thermoset materials. In this work, we have prepared polyamide-6 (PA6) and PA6/fiber composites by T-RTM of caprolactam. Glass and carbon fibers were employed in a fixed amount of 60 and 47 wt.%, respectively. Neat PA6 and PA6 matrices (of PA6-GF and PA6-CF) of approximately 200 kg/mol were obtained with conversion ratios exceeding 95%. Both carbon fibers (CF) and glass fibers (GF) were able to nucleate PA6, with efficiencies of 44% and 26%, respectively. The α crystal polymorph of PA6 was present in all samples. The lamellar spacing, lamellar thickness and crystallinity degree did not show significant variations in the samples with or without fibers as result of the slow cooling process applied during T-RTM. The overall isothermal crystallization rate decreased in the order: PA6-CF > PA6-GF > neat PA6, as a consequence of the different nucleation efficiencies. The overall crystallization kinetics data were successfully described by the Avrami equation. The lamellar stack morphology observed by atomic force microscopy (AFM) is consistent with 2D superstructural aggregates (n = 2) for all samples. Finally, the reinforcement effect of fibers was larger than one order of magnitude in the values of elastic modulus and tensile strength.

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Section: Introductionmentioning

confidence: 99%

Nucleation and Crystallization of PA6 Composites Prepared by T-RTM: Effects of Carbon and Glass Fiber Loading

et al. 2019

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“…1 shows that at 453 K the resin viscosity is directed by two growth regimes which are caused by the different time spans of the polymerization and the crystallization during the PA6 synthesis. Indeed, at 453 K the polymerization and the crystallization occur successively, which makes the lower slope between the two growth regimes the mark of the transition between these two phenomena [5]. Fig.…”

Section: Isothermal Rheology At 453 Kmentioning

confidence: 97%

“…The reactants used for PA6 polymerization in the rheological study comes from components provided by Brüggemann Chemical, Germany which are detailed in Table 1. The ratio of both the catalyst and the activator is defined at 0.79/1.10mol.% of the monomer, which was previously studied in order to determine its polymerization and crystallization kinetics [5]. To ensure minimal inhibition from humidity, the reactants are dried before use.…”

Section: Reactive MIXmentioning

confidence: 99%

“…As shown by Imbert et al [4], the intra-tow flow itself is also transient but on a different time scale with storage and release of resin. In a recent study, Vicard et al [5] used differential scanning calorimetry (DSC) to gather experimental data on a reactive mix with suitable synthesis duration for LCM processes. This has highlighted the different synthesis characteristics with relation to temperature and allowed the identification of a modified Hillier coupling of polymerization and crystallization model.…”

Section: Text 1 Introductionmentioning

confidence: 99%

“…Then, a preliminary modelling procedure to simulate the flow of the reactive mix is presented. It integrates the polymerization kinetics from Vicard et al [5] and the rheokinetics proposed by Davé et al [6]. A simulation illustrating the modelling procedure is showcased.…”

Section: Text 1 Introductionmentioning

confidence: 99%

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Modeling the reactive PA6 flow for LCM processes

Han¹,

Govignon²,

Cantarel³

et al. 2021

Esaform 2021

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Fiber reinforced thermoplastic composites have shown to be attractive for industry as they can be reused, reshaped, welded and repaired, while keeping mechanical properties on par with thermoset composites. Since thermoplastics usually have high melt viscosities unsuitable for liquid composite molding processes, in-situ synthesis of PA6 from ε-caprolactam is considered. Its reactive mix has low viscosity which allows impregnation. However, the coupled crystallization and polymerization affects the resin viscosity and its flow is altered by the dual-scale permeability of the fiber preform. Thus, to predict the local differences in the thermoplastics properties, a coupled polymerization crystallization model needs to be integrated in the LCM processing simulation at representative scales. This study aims to propose a reliable simulation of the resin flow through a fibrous preform. Hence, viscosity measurements on the reactive mix are achieved using a rheometer with parallel-plate geometry, aiming to associate a viscosity model with the Hillier coupled polymerization-crystallization model previously determined by Vicard. The full chemorheological model will then be integrated into a simulation of LCM process in OpenFOAM®, an open source CFD software in order to follow the extent of the synthesis in the resin flow during the process. As a future work, simulations including microscale tow information extracted from a real textile specimen will permit to investigate the effect of permeability and double scale porosity in fibrous preforms on the final polymerization rate and crystallinity.

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Isothermal anionic polymerization of ε‐caprolactam to polyamide‐6: Kinetic modeling and application for production process

Kurt,

Bratzdrum,

Chaloupka

et al. 2023

J of Applied Polymer Sci

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The in‐situ anionic polymerization of ε‐caprolactam (ε‐CL) to polyamide‐6 enables the production of large, near net shape fiber reinforced composites by thermoplastic resin transfer molding. For the propagation of the flow front as well as for the progress of the solidification, the simultaneous processes of polymerization and crystallization and the corresponding reaction kinetics play a central role. To investigate these processes, preparation of reactive mixtures consisting of ε‐CL, activator, and initiator was carried out under inert atmosphere. A solvent‐based activator and initiator were used, which hardly have been studied in the literature so far. In analogy to the resin transfer molding process, quasi‐isothermal differential scanning calorimetry measurements were performed at various temperatures and the released enthalpy and the degree of crystallization were determined. From these isothermal measurements, a two‐stage semi‐empirical kinetic model was established for a solvent‐based system for the first time, which reproduces the experimental data with high precision. To apply the obtained kinetic model to a thermoplastic resin transfer molding process it was finally correlated to dielectric sensor data, allowing real‐time prediction of the total conversion.

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Modeling of the polymerization and crystallization kinetic coupling of polyamide 6 synthesized from ε-caprolactam

Cited by 10 publications

References 55 publications

Nucleation and Crystallization of PA6 Composites Prepared by T-RTM: Effects of Carbon and Glass Fiber Loading

Nucleation and Crystallization of PA6 Composites Prepared by T-RTM: Effects of Carbon and Glass Fiber Loading

Modeling the reactive PA6 flow for LCM processes

Isothermal anionic polymerization of ε‐caprolactam to polyamide‐6: Kinetic modeling and application for production process

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