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Recycling PLA to multifunctional oligomeric compatibilizers for PLA/starch composites
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.ORCID iD: 0000-0002-7790-8987
2015 (English)In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 64, 126-137 p.Article in journal (Refereed) Published
Abstract [en]

Simple one-pot valorization of poly(lactic acid) (PLA) to green additives was demonstrated. PLA was thermally recycled in the presence of polyols, which accelerated the degradation process by reacting with PLA chains. As a result low molecular weight oligomers with polyols end-groups were formed. The reaction between PLA and multifunctional alcohols i.e. glycerol, sorbitol, glucose and starch were confirmed by FTIR, H-1 NMR, SEC and MALDI-MS. The resulting amphiphilic products were evaluated as compatibilizer candidates for PLA/starch blends. Multiple techniques demonstrated that the obtained oligomers strengthened the interfacial adhesion and improved the compatibility and flexibility of extruded and melt-blended PLA/starch composites. The developed one-pot procedure required no solvent or catalyst offering good possibilities for up-scaling. It was, thus, demonstrated that PLA can be recycled to low molecular weight compatibilizers by simple process of thermal heating in the presence of polyols. This provides profound promise for retaining the material value of old PLA products at the same time as biobased additives are produced.

Place, publisher, year, edition, pages
2015. Vol. 64, 126-137 p.
Keyword [en]
Poly (lactic acid), Starch, Polyol, Composites, Compatibilizer, Recycling
National Category
Polymer Technologies
Identifiers
URN: urn:nbn:se:kth:diva-163454DOI: 10.1016/j.eurpolymj.2015.01.004ISI: 000350525100013Scopus ID: 2-s2.0-84921263297OAI: oai:DiVA.org:kth-163454DiVA: diva2:800962
Note

QC 20150408

Available from: 2015-04-08 Created: 2015-04-07 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Closed-loop strategy for recycling of starch and poly (lactic acid) into new materials
Open this publication in new window or tab >>Closed-loop strategy for recycling of starch and poly (lactic acid) into new materials
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Biopolymers such as starch and poly lactic acid (PLA) can be derived from agriculture and are among the most promising biobased plastics for packaging and other short term application. Considering the growing pressure of environmental safety and limited resources on our planet, it would be beneficial to retain the value of waste products by material recycling. A closed-loop strategy from feedstock recycling of biopolymers to utilization of the obtained degradation products as property enhancers in the same biopolymers was demonstrated in the thesis. 

Place, publisher, year, edition, pages
Stockholm,: KTH Royal Institute of Technology, 2015. 43 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2015:21
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-167353 (URN)978-91-7595-557-5 (ISBN)
Presentation
2015-06-08, K2, KTH, Teknikringen 28, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20150522

Available from: 2015-05-22 Created: 2015-05-21 Last updated: 2015-05-22Bibliographically approved
2. Closed-loop strategy for valorization of starch: From starch to functionalized starch biomaterials and bioplastics
Open this publication in new window or tab >>Closed-loop strategy for valorization of starch: From starch to functionalized starch biomaterials and bioplastics
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The desire to utilize renewable resources and avoid wastes drives us to develop new concepts for material design. Non-edible starch feedstocks and starch bioplastic wastes were previously considered useless. However, with a proper design and process chain, starch-rich biomasses are a promising resource for production and modification of future materials. Therefore, a top-down and closed-loop strategy for valorization of starch through a circle consisting of “StarchÞEnhancerÞNew starch product” is developed and demonstrated in this work. Starch, as a model for starch rich waste resources, was converted into valuable chemicals or carbon products through a two-step decomposition. The valorization products were then utilized as property enhancers in starch-rich biomaterials and bioplastics through design of “structure adapted utilization”: i.e., the obtained products were included in the design of starch-rich products aiming at property enhancement or introduction of new properties. This leads to the closed-loop strategy for valorization of starch.

Through a two-step processing, starch was converted into two categories of value-added products: water soluble degradation products (mixture of glucose, levulinic acid (LA) and formic acid (FA)), and 0D nano-graphene oxide (nGO, smaller than 100 nm in all dimension). Specifically, in step one, through acid-catalyzed microwave-assisted reaction; starch was converted to a mixture of glucose, LA and FA in soluble phase and carbon spheres (C-spheres) as a solid residue phase. In step two, the insoluble C-spheres were further oxidized under oxygen-rich acidic conditions to obtain multifunctional nGO.

Through “structure adapted utilization”, four routes were designed to efficiently utilize the two categories of value-added products as functional enhancers for new starch-rich products. On one hand, starch-derived biomedical scaffolds were developed in route 1 and 2: nGO could stabilize porous 3D starch scaffolds (route 1) and starch nanofibrous scaffolds (route 2), and meanwhile endorse them the ability to induce biomineralization. On the other hand, starch-rich (and fully starch-derivable) bioplastics were developed in route 3 and 4: nGO effectively compatibilized poly lactic acid/starch composites enhancing the mechanical performance and barrier properties (route 3) and the water soluble degradation products plasticized starch films reducing their brittleness (route 4).

Along this closed-loop pathway, the material value of starch was significantly improved and minimum waste was derived, paving towards the sustainable environment and circular economy. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 60 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2017:22
Keyword
Starch, Nano-graphene oxide, Microwave, Valorization, Scaffold, Biomineralization, Bioplastics, Compatibilizer, Plasticizer
National Category
Materials Engineering Medical Materials Medical and Health Sciences
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-208188 (URN)978-91-7729-341-5 (ISBN)
Public defence
2017-05-05, F3, Lindstedtsvägen 26, 10:00
Opponent
Supervisors
Note

QC 20170602

Available from: 2017-06-02 Created: 2017-06-01 Last updated: 2017-06-02Bibliographically approved

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