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Agro-Waste Derived Additives for Polylactide and Tapioca Starch
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Development of materials from renewable resources is one of the big challenges facing our world. In this thesis agro-industrial waste derivatives were developed and evaluated as additives for two common renewable polymer matrices, polylactide (PLA) and starch. Two waste products, wood flour (WF) and rice bran (RB) were evaluated in different forms. Milled WF and RB were either used directly to prepare PLA and starch biocomposites or they were liquefied by acid catalyzed hydrolysis to low molecular weight products. The complex polyol mixtures from liquefaction were tested directly as PLA and starch additives or utilized as monomers for synthesis of esters. The synthesized esters were evaluated as plasticizers for PLA and starch. The effect of different additives on tensile properties, miscibility, surface chemistry and morphology were evaluated by Instron, DSC, FTIR, FTIR imaging and SEM. In the case of polylactide films the influence of additives on hydrolytic degradation rate and process was evaluated by following the weight loss, surface changes, compositional changes and/or water-soluble migrants and degradation products by FTIR, SEM, pyrolysis-GC-MS and ESI-MS. The most marked difference in mechanical properties was observed in the case of PLA modified with liquefied wood flour derived ester plasticizer (PWF). Addition of 10 and 30 weight-% plasticizer increased the strain at break from a few percent for pure PLA to over 100 and 300%, respectively. The liquefied rice bran based ester, however, did not form miscible blends with PLA and it did not function as plasticizer. In some cases the impact of additives on the following degradation process was significant. Depending on the used additive, they could either concentrate in the matrix during the hydrolysis of polylactide or they were rapidly released to the surrounding water. In some cases clear hydrolysis catalyzing effects were observed. Liquefied rice bran in combination with mineral fillers and/or traditional plasticizers seemed to have the best potential as starch plasticizer.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , 60 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2012:29
Keyword [en]
Agro-industrial waste, wood flour, rice bran, polylactide, starch, biomass, degradation
National Category
Polymer Technologies
Research subject
SRA - E-Science (SeRC)
Identifiers
URN: urn:nbn:se:kth:diva-95290ISBN: 978-91-7501-378-7 (print)OAI: oai:DiVA.org:kth-95290DiVA: diva2:527473
Public defence
2012-06-11, K2, Teknikringen 28, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish e‐Science Research Center
Note

QC 20120528

Available from: 2012-05-28 Created: 2012-05-21 Last updated: 2013-05-23Bibliographically approved
List of papers
1. Pyrolysis-GC-MS reveals important differences in hydrolytic degradation process of wood flour and rice bran filled polylactide composites
Open this publication in new window or tab >>Pyrolysis-GC-MS reveals important differences in hydrolytic degradation process of wood flour and rice bran filled polylactide composites
2012 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, no 3, 281-287 p.Article in journal (Refereed) Published
Abstract [en]

Pyrolysis-GC-MS of polylactide (PLA) biocomposites before and after hydrolytic degradation revealed prominent differences in the hydrolytic degradation process of rice bran and wood flour filled biocomposites. The water uptake and mass loss for polylactide/wood flour composites were similar to that of plain PLA. Pyrolysis-GC-MS, however, showed that on prolonged ageing the hydrolysis of PLA led to increased wood flour concentration in the remaining biocomposite matrices. In contrast, the polylactide/rice bran composites exhibited larger water uptake and higher mass loss. Pyrolysis-GC-MS and FTIR analysis proved that the higher mass loss was caused by migration of rice bran from the composites. The type of natural filler could thus greatly influence the degradation process and/or the stability of the materials in aqueous or humid environments.

Keyword
Polylactide, Wood flour, Rice bran, Biocomposite, Hydrolysis, Pyrolysis-GC-MS
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-92330 (URN)10.1016/j.polymdegradstab.2011.12.017 (DOI)000300923500011 ()2-s2.0-84856253267 (Scopus ID)
Note
QC 20120419Available from: 2012-04-19 Created: 2012-04-02 Last updated: 2017-12-07Bibliographically approved
2. Liquefied Wood Flour and Rice Bran as Polylactide Additives
Open this publication in new window or tab >>Liquefied Wood Flour and Rice Bran as Polylactide Additives
(English)Article in journal (Other academic) Submitted
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-95496 (URN)
Note
QS 2012Available from: 2012-05-28 Created: 2012-05-28 Last updated: 2012-05-28Bibliographically approved
3. Liquefied biomass derived plasticizer for polylactide
Open this publication in new window or tab >>Liquefied biomass derived plasticizer for polylactide
2013 (English)In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 88, no 5, 897-903 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: The valorization of renewable agro-industrial residues and their further utilization for production of polymers and polymer additives is a highly attractive alternative for replacement of oil-based materials. RESULTS: Liquefied wood flour and rice bran derived esters were synthesized and evaluated as novel green plasticizers for polylactide (PLA). The liquefied wood flour ester (PWF) showed good miscibility with PLA and good plasticization efficiency as shown by differential scanning calorimetry (DSC) and tensile testing. Tensile strain at break increased from a few percent for pure PLA to over 100 and 300% for the materials containing 10 and 30 wt-% of PWF. The addition of PWF accelerated the hydrolysis rate of PLA as shown by faster weight loss during aging in water and faster formation of water-soluble lactic acid oligomers, which was shown by electrospray ionization mass spectrometry (ESI-MS) analysis of the migrants. The liquefied rice bran based product (PRB) was not miscible with PLA and it did not improve the elongation at break of PLA. Rice bran is generally rich in arabinoxylans with only secondary less reactive alcohol groups. The larger number of un-reacted hydroxyl-groups in PRB was confirmed by Fourier transform infrared (FTIR) spectroscopy and could explain the immiscibility with PLA. CONCLUSIONS: The results demonstrate that the synthesized liquefied wood flour derived plasticizer could have great potential as a biobased polylactide plasticizer.

Keyword
polylactide, biomass, green chemistry, plasticizer, wood, agro-waste, valorization
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-95498 (URN)10.1002/jctb.3918 (DOI)000317674400021 ()2-s2.0-84876317066 (Scopus ID)
Funder
Swedish Research Council, 2010-3877
Note

QC 20130523. Updated from submitted to published.

Available from: 2012-05-28 Created: 2012-05-28 Last updated: 2017-12-07Bibliographically approved
4. Tuning the mechanical properties of tapioca starch by plasticizers, inorganic and agro-waste derived fillers
Open this publication in new window or tab >>Tuning the mechanical properties of tapioca starch by plasticizers, inorganic and agro-waste derived fillers
2012 (English)In: Polymer science, ISSN 0965-545X, Vol. 2012, no Article ID 463298Article in journal (Refereed) Published
Abstract [en]

Mechanical properties of tapioca starch-based films were tuned by different additives and additive combinations. The additives included plasticizers (glycerol, sorbitol, and citric acid), inorganic fillers (halloysite and kaolin), and agrowaste-based fillers (milled wood flour and rice bran). In addition, new biobased additives were prepared from wood flour and rice bran through liquefaction reaction. Through different additive combinations, starch-based materials with significant differences in tensile properties were designed. Addition of halloysite nanoclay resulted in materials with improved tensile strength at break and rather low strain at break. The effect of kaolin on tensile strength was highly dependent on the used plasticizer. However, in most combinations the addition of kaolin resulted in materials with intermediate tensile strength and strain at break values. The addition of milled wood flour and rice bran improved the tensile strength, while the addition of liquefied fillers especially liquefied rice bran increased the strain at break indicating that liquefied rice bran could have potential as a plasticizer for starch blends.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2012
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-95499 (URN)10.5402/2012/463298 (DOI)
Note

QC 20121121

Available from: 2012-05-28 Created: 2012-05-28 Last updated: 2017-12-07Bibliographically approved

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