Compostability of Co-Extruded Starch/Poly(Lactic Acid) Polymeric Material Degradation in an Activated Inert Solid Medium

The aim of this work was to estimate the biodegradation of a co-extruded starch/poly(lactic acid) polymeric material using a vermiculite based inert solid medium which could simulate compost medium and enable us to achieve complete carbon balances. At the end of the test the mineralisation rate was compared to those obtained for co-extruded starch/poly(lactic acid) polymeric material degradation in compost. It was shown that the mineralisation rate after 45 days of degradation was similar in activated vermiculite medium to the one in compost. A protocol for both extraction and quantification of the carbon included in the different degradation by-products was proposed and the carbon balance of the polymer degradation was followed during the test with a satisfactory accuracy. As the non-degraded PLA and starch material had been retrieved during the test, the evolution of the glass transition temperature and the molecular weight of PLA could be followed. A two-step degradation mechanism was highlighted in inert solid medium, showing the fundamental role of abiotic reactions for PLA degradation in compost

Mise au point d'un milieu solide inerte pour l'étude de la biodégradation des polymères dans le compost

Le but de nos travaux est de mettre au point un milieu solide inerte à base de Vermiculite (matériau 100% minéral) qui permette une meilleure répétabilité que les tests en compost mais aussi de simuler la biodégradation dans le compost et d'établir des bilans carbone complets. L'amidon a été utilisé dans un premier temps comme polymère biodégradable " modèle ". Nous avons pu montrer que la dégradation de l'amidon dans un milieu solide inerte activé est en tous points similaire à celle observée dans le compost. Nous avons ensuite établi un bilan carbone par diverses techniques d'extraction et d'analyse courantes avec une précision satisfaisante. Dans un second temps, plusieurs protocoles d'extraction des sous-produits de dégradation ont été mis au point pour le bilan carbone de la dégradation du PLA. Une méthode satisfaisante basée sur l'hydrolyse du polymère dans la soude et le dosage de l'acide lactique libéré, nous a permis de suivre la disparition du polymère du milieu. Ainsi nous avons suivi l'évolution des différents termes du bilan carbone dans le temps, biomasse, produits solubles dans l'eau, polymère non dégradé et carbone minéralisé en CO2. Une méthode différente a été adoptée pour le bilan carbone de la biodégradation du PHB. Ces travaux ont permis de mettre en évidence les points clefs sur lesquels les futures expériences devront porter pour permettre une généralisation des méthodes d'estimation du bilan carbone en milieu solide inerte.The purpose of our research was to set up a vermiculite based inert solid medium which allows us to enhance reproductibility of biodegradation tests in compost, to simulate degradation of materials in compost and to establish carbon balance. In a first step, wheat starch has been used as a model biodegradable polymer and we have shown that degradation of this product in an inert solid medium was similar to the degradation in compost. A carbon balance has been established with a satisfactory accuracy. In a second step, we have applied the method to the degradation of synthetic biodegradable polymer such as PLA of PHB. A carbon extraction protocol based on PLA hydrolysis in NaOH has been proposed and we have followed the evolution of the various terms of the PLA degradation carbon balance, Biomass, carbon dioxide, soluble by-products and remaining polymer. A different protocol has been proposed of PHB based on biomass oxidation but it still needs some improvement. This work constitutes a first approach in polymer inert solid media degradation tests and it highlights the fundamental steps which further work should be focused on.REIMS-BU Sciences (514542101) / SudocSudocFranceF

The Role Played by Acetyl Group Distribution Patterns in Substituted Starch Toward Enzymatic De-acetylation and Chain Fragmentation

International audienceThe nature and distribution of the acetylated groups were evaluated by 13C-NMR and 1H-NMR. The starch substrate with a DS of 1.5 comprises only two patterns: α-(1→4)-d-glucopyranose and 2,3,6-tri-O-acetyl-α-(1→4)-d-glucopyranose. The starch with a DS of 3.0 also comprises two patterns: 2,3,4,6-tetra-O-acetyl-α-(1→4)-d-glucopyranose and 2,3,6-tri-O-acetyl-α-(1→4)-d-glucopyranose; whereas starch (DS = 1.9) contains 4 patterns: 2,3,6-tri-O-acetyl-α-(1→4)-d-glucopyranose, 2,3,4,6-tetra-O-acetyl-α-(1→4)-d-glucopyranose terminal, 2,6-di-O-acetyl-α-(1→4)-d-glucopyranose, and 3,6-di-O-acetyl-α-(1→4)-d-glucopyranose. Using esterase from Viscozyme, it has been possible to hydrolyze up to 7% of the DS 3.0 starch. An α-amylase (Fungamyl 800) was then added to these acetylesterases. With a 2.4 FAU/mL fraction of α-amylase and 2.4 U/mL from the Viscozyme's acetylesterase, 28% of the acetylated end groups were hydrolyzed for the starch substrates with DS 3.0. Moreover, a synergic action between α-amylase and acetylesterase was noticed, allowing fragmentation of 32% for DS 1.5, 30% for DS 1.9, and 11% for DS 3.0

Graph Based Method for the Modelling of Crumpled Structures

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Modelling of the crumpling process of a paper sheet

International audienceThe packaging sector needs innovative solutions to face both the worldwide competitiveness between companies and sustainable development issues. In response to this demand, this paper proposes the study of a new folding technique which erects 3D structures from a single flexible sheet. This technique consists in creating a network of complex patterns according to a crumpling process that generates random folds. In order to give a better understanding on the crumpling process, a descriptive modelling is proposed. It highlights useful and useless characteristics conferred to a flexible sheet and gives ways for the development of graph based methods more adapted to the modelling of crumpled structures. A study case on a food packaging supports the proposition

Geometric and topological modelling of 3D crumpled structures

International audienceCrumpling is a new method derived of the origami techniques that transforms a single paper sheet into a three-dimensional structure by a systematic generation of random folds. The resulting crumpled object is an innovative answer to packaging industries that need attractive and dynamic products in a sustainable context. In order to understand the performances of crumpled structures and their applications in the field of packaging, this paper firstly details the fundamental characteristics of crumpled surfaces by expressing categories of crumpled creases patterns and patterns networks. The crumpled surfaces connectivity is then studied in an Extended Attributed Adjacency Graph by adding new faces and edges attributes

Modelling of the crumpling process of a paper sheet

International audienceThe packaging sector needs innovative solutions to face both the worldwide competitiveness between companies and sustainable development issues. In response to this demand, this paper proposes the study of a new folding technique which erects 3D structures from a single flexible sheet. This technique consists in creating a network of complex patterns according to a crumpling process that generates random folds. In order to give a better understanding on the crumpling process, a descriptive modelling is proposed. It highlights useful and useless characteristics conferred to a flexible sheet and gives ways for the development of graph based methods more adapted to the modelling of crumpled structures. A study case on a food packaging supports the proposition

Geometric and topological modelling of 3D crumpled structures

International audienceCrumpling is a new method derived of the origami techniques that transforms a single paper sheet into a three-dimensional structure by a systematic generation of random folds. The resulting crumpled object is an innovative answer to packaging industries that need attractive and dynamic products in a sustainable context. In order to understand the performances of crumpled structures and their applications in the field of packaging, this paper firstly details the fundamental characteristics of crumpled surfaces by expressing categories of crumpled creases patterns and patterns networks. The crumpled surfaces connectivity is then studied in an Extended Attributed Adjacency Graph by adding new faces and edges attributes

Enzymatic degradation and deacetylation of native and acetylated starch-based extruded blends

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Crumpling of paper sheet and packaging

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