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Mechanical Behavior—Microstructure Relationships in Injection-Molded Polyamide 66

Clear relationships between the semi-crystalline microstructure of injection molding polymers and their mechanical behavior are not yet totally established for all polymers. Part of this relative lack of understanding is because an unambiguous scientific approach is difficult to build up. The proces...

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Detalles Bibliográficos
Autores principales: Billon, Noëlle, Giraudeau, Joan, Bouvard, Jean Luc, Robert, Gilles
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6403566/
https://www.ncbi.nlm.nih.gov/pubmed/30960972
http://dx.doi.org/10.3390/polym10101047
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author Billon, Noëlle
Giraudeau, Joan
Bouvard, Jean Luc
Robert, Gilles
author_facet Billon, Noëlle
Giraudeau, Joan
Bouvard, Jean Luc
Robert, Gilles
author_sort Billon, Noëlle
collection PubMed
description Clear relationships between the semi-crystalline microstructure of injection molding polymers and their mechanical behavior are not yet totally established for all polymers. Part of this relative lack of understanding is because an unambiguous scientific approach is difficult to build up. The processing of samples promotes a microstructure which is not uniform and can be described in various ways on different scales. This introduces uncertainty in the correlations. Most completed studies were conducted on polyolefin, which exhibits an evolution of microstructure that is quite easy to observe and to correlate to mechanical properties. This paper intends to illustrate a more diffuse case. To achieve this, combined characterizations along the flow path and throughout the thickness of a plaque as well as characterizations of the local microstructure and tensile behavior of polyamide 66 are described. The microstructure was explored in terms of skin-core structure, spherulites sizes, crystallinity ratio and lamellae organization. Mechanical properties were addressed with non-monotonic tests with the use of DIC (Digital Image Correlation) to assess true behavior. The effect of humidity is also accounted for. It is demonstrated that small changes in lamellae or interlamellar amorphous phase are likely to be responsible for non-uniform mechanical properties, whereas more macroscopic levels (skin core structure, spherulites level of crystallinity ratio) appeared to be irrelevant levels of description. Consequently, the usual simplified analyses based on optical microscopy and differential scanning calorimetry (DSC) can be inefficient in improving knowledge in that field.
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spelling pubmed-64035662019-04-02 Mechanical Behavior—Microstructure Relationships in Injection-Molded Polyamide 66 Billon, Noëlle Giraudeau, Joan Bouvard, Jean Luc Robert, Gilles Polymers (Basel) Article Clear relationships between the semi-crystalline microstructure of injection molding polymers and their mechanical behavior are not yet totally established for all polymers. Part of this relative lack of understanding is because an unambiguous scientific approach is difficult to build up. The processing of samples promotes a microstructure which is not uniform and can be described in various ways on different scales. This introduces uncertainty in the correlations. Most completed studies were conducted on polyolefin, which exhibits an evolution of microstructure that is quite easy to observe and to correlate to mechanical properties. This paper intends to illustrate a more diffuse case. To achieve this, combined characterizations along the flow path and throughout the thickness of a plaque as well as characterizations of the local microstructure and tensile behavior of polyamide 66 are described. The microstructure was explored in terms of skin-core structure, spherulites sizes, crystallinity ratio and lamellae organization. Mechanical properties were addressed with non-monotonic tests with the use of DIC (Digital Image Correlation) to assess true behavior. The effect of humidity is also accounted for. It is demonstrated that small changes in lamellae or interlamellar amorphous phase are likely to be responsible for non-uniform mechanical properties, whereas more macroscopic levels (skin core structure, spherulites level of crystallinity ratio) appeared to be irrelevant levels of description. Consequently, the usual simplified analyses based on optical microscopy and differential scanning calorimetry (DSC) can be inefficient in improving knowledge in that field. MDPI 2018-09-20 /pmc/articles/PMC6403566/ /pubmed/30960972 http://dx.doi.org/10.3390/polym10101047 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Billon, Noëlle
Giraudeau, Joan
Bouvard, Jean Luc
Robert, Gilles
Mechanical Behavior—Microstructure Relationships in Injection-Molded Polyamide 66
title Mechanical Behavior—Microstructure Relationships in Injection-Molded Polyamide 66
title_full Mechanical Behavior—Microstructure Relationships in Injection-Molded Polyamide 66
title_fullStr Mechanical Behavior—Microstructure Relationships in Injection-Molded Polyamide 66
title_full_unstemmed Mechanical Behavior—Microstructure Relationships in Injection-Molded Polyamide 66
title_short Mechanical Behavior—Microstructure Relationships in Injection-Molded Polyamide 66
title_sort mechanical behavior—microstructure relationships in injection-molded polyamide 66
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6403566/
https://www.ncbi.nlm.nih.gov/pubmed/30960972
http://dx.doi.org/10.3390/polym10101047
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