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Closed-loop strategy for recycling of starch and poly (lactic acid) into new materials
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
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: urn:nbn:se:kth:diva-167353ISBN: 978-91-7595-557-5 (print)OAI: oai:DiVA.org:kth-167353DiVA: diva2:813207
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
List of papers
1. A Closed-Loop Process from Microwave-Assisted Hydrothermal Degradation of Starch to Utilization of the Obtained Degradation Products as Starch Plasticizers
Open this publication in new window or tab >>A Closed-Loop Process from Microwave-Assisted Hydrothermal Degradation of Starch to Utilization of the Obtained Degradation Products as Starch Plasticizers
2014 (English)In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 2, no 9, 2172-2181 p.Article in journal (Refereed) Published
Abstract [en]

A green closed-loop water-based process for chemical recycling of starch was demonstrated. The process starts from microwave-assisted controllable starch degradation to functional chemicals and continues to utilization of the formed degradation products, glucose and levulinic acid (LA), as starch plasticizers. The degradation process and the effect of process parameters on the formed degradation products and residues were carefully fingerprinted by multiple techniques, e.g., NMR, ESI-MS, FTIR imaging, UV-vis, and SEM. The degradation process took place in three steps, proceeding from rupture of starch granules and oligosaccharide formation to further hydrolysis to glucose. Finally, at well-defined time point rapid degradation of glucose to LA and formic acid (FA) was initiated through a 5-hydroxymethyl furfural (5-HMF) intermediate. 5-HMF also participated in carbonization reactions leading to formation of solid carbon spheres. Through selection of processing parameters, LA could be produced in high yield with 9596 selectivity. The results demonstrated that microwave-assisted degradation of starch leads to well-defined controllable degradation products. These products are directly reusable as plasticizers for new starch products, which suggest great opportunities for biomass and starch recycling, opening the door toward potential industrial applications.

Keyword
Hydrothermal degradation, Levulinic acid, Microwave, Plasticizer, Recycling, Starch
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-152562 (URN)10.1021/sc500355w (DOI)000341229100012 ()2-s2.0-84906880167 (Scopus ID)
Note

QC 20140929

Available from: 2014-09-29 Created: 2014-09-29 Last updated: 2017-06-02Bibliographically approved
2. Recycling PLA to multifunctional oligomeric compatibilizers for PLA/starch composites
Open this publication in new window or tab >>Recycling PLA to multifunctional oligomeric compatibilizers for PLA/starch composites
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.

Keyword
Poly (lactic acid), Starch, Polyol, Composites, Compatibilizer, Recycling
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-163454 (URN)10.1016/j.eurpolymj.2015.01.004 (DOI)000350525100013 ()2-s2.0-84921263297 (Scopus ID)
Note

QC 20150408

Available from: 2015-04-08 Created: 2015-04-07 Last updated: 2017-12-04Bibliographically approved

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