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Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends

The mechanical behavior of polymer materials is heavily influenced by a phenomenon known as crazing. Crazing is a precursor to damage and leads to the formation of cracks as it grows in both thickness and tip size. The current research employs an in situ SEM method to investigate the initiation and...

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Autores principales: Hosseinnezhad, Ramin, Elumalai, Dhanumalayan, Vozniak, Iurii
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10650116/
https://www.ncbi.nlm.nih.gov/pubmed/37959914
http://dx.doi.org/10.3390/polym15214234
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author Hosseinnezhad, Ramin
Elumalai, Dhanumalayan
Vozniak, Iurii
author_facet Hosseinnezhad, Ramin
Elumalai, Dhanumalayan
Vozniak, Iurii
author_sort Hosseinnezhad, Ramin
collection PubMed
description The mechanical behavior of polymer materials is heavily influenced by a phenomenon known as crazing. Crazing is a precursor to damage and leads to the formation of cracks as it grows in both thickness and tip size. The current research employs an in situ SEM method to investigate the initiation and progression of crazing in all-biopolymeric blends based on Polyhydroxyalkanoates (PHAs). To this end, two chemically different grades of PHA, namely poly(hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV), were melt-blended with polybutyrate adipate terephthalate (PBAT). The obtained morphologies of blends, the droplet/fibrillar matrix, were highly influenced by the plasticity of the matrices as well as the content of the minor phase. Increasing the concentration of PBAT from 15 to 30 wt.% resulted in the brittle to ductile transition. It changed the mechanism of plastic deformation from single craze-cracking to homogeneous and heterogeneous intensified crazing for PHB and PHBHV matrices, respectively. Homogeneous tensile crazes formed perpendicularly to the draw direction at the initial stages of deformation, transformed into shear crazes characterized by oblique edge propagation for the PHBHV/PBAT blend. Such angled crazes suggested that the displacement might be caused by shear localized deformation. The crazes’ strength and the time to failure increased with the minor phase fibers. These fibers, aligned with the tensile direction and spanning the width of the crazes, were in the order of a few micrometers in diameter depending on the concentration. The network of fibrillar PBAT provided additional integrity for larger plastic deformation values. This study elucidates the mechanism of crazing in PHA blends and provides strategies for controlling it.
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spelling pubmed-106501162023-10-26 Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends Hosseinnezhad, Ramin Elumalai, Dhanumalayan Vozniak, Iurii Polymers (Basel) Article The mechanical behavior of polymer materials is heavily influenced by a phenomenon known as crazing. Crazing is a precursor to damage and leads to the formation of cracks as it grows in both thickness and tip size. The current research employs an in situ SEM method to investigate the initiation and progression of crazing in all-biopolymeric blends based on Polyhydroxyalkanoates (PHAs). To this end, two chemically different grades of PHA, namely poly(hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV), were melt-blended with polybutyrate adipate terephthalate (PBAT). The obtained morphologies of blends, the droplet/fibrillar matrix, were highly influenced by the plasticity of the matrices as well as the content of the minor phase. Increasing the concentration of PBAT from 15 to 30 wt.% resulted in the brittle to ductile transition. It changed the mechanism of plastic deformation from single craze-cracking to homogeneous and heterogeneous intensified crazing for PHB and PHBHV matrices, respectively. Homogeneous tensile crazes formed perpendicularly to the draw direction at the initial stages of deformation, transformed into shear crazes characterized by oblique edge propagation for the PHBHV/PBAT blend. Such angled crazes suggested that the displacement might be caused by shear localized deformation. The crazes’ strength and the time to failure increased with the minor phase fibers. These fibers, aligned with the tensile direction and spanning the width of the crazes, were in the order of a few micrometers in diameter depending on the concentration. The network of fibrillar PBAT provided additional integrity for larger plastic deformation values. This study elucidates the mechanism of crazing in PHA blends and provides strategies for controlling it. MDPI 2023-10-26 /pmc/articles/PMC10650116/ /pubmed/37959914 http://dx.doi.org/10.3390/polym15214234 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/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 (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Hosseinnezhad, Ramin
Elumalai, Dhanumalayan
Vozniak, Iurii
Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends
title Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends
title_full Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends
title_fullStr Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends
title_full_unstemmed Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends
title_short Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends
title_sort approaches to control crazing deformation of pha-based biopolymeric blends
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10650116/
https://www.ncbi.nlm.nih.gov/pubmed/37959914
http://dx.doi.org/10.3390/polym15214234
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