| 1. |
- Arza, Carlos R., et al.
(författare)
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Synthesis, Thermal Properties, and Rheological Characteristics of Indole-Based Aromatic Polyesters
- 2019
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:12, s. 15012-15021
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Tidskriftsartikel (refereegranskat)abstract
- Currently, there is an intensive development of bio-based aromatic building blocks to replace fossil-based terephthalates used for poly(ethylene terephthalate) production. Indole is a ubiquitous aromatic unit in nature, which has great potential as a bio-based feedstock for polymers or plastics. In this study, we describe the synthesis and characterization of new indole-based dicarboxylate monomers with only aromatic ester bonds, which can improve the thermal stability and glass-transition temperature (Tg) of the resulting polyesters. The new dicarboxylate monomers were polymerized with five aliphatic diols to yield 10 new polyesters with tunable chemical structures and physical properties. Particularly, the Tg values of the obtained polyesters can be as high as 113 °C, as indicated by differential scanning calorimetry and dynamic mechanical analysis. The polyesters showed decent thermal stability and distinct flow transitions as revealed by thermogravimetric analysis and rheology measurements.
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| 2. |
- Mankar, Smita, et al.
(författare)
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Synthesis, life cycle assessment, and polymerization of a vanillin-based spirocyclic diol toward polyesters with increased glass transition temperature
- 2019
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Ingår i: ACS Sustainable Chemistry & Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 7:23, s. 19090-19103
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Tidskriftsartikel (refereegranskat)abstract
- Bio-based rigid diols are key building blocks in the development and preparation of high performance bioplastics with improved thermal and dimensional stability. Here, we report on the straightforward two-step synthesis of a diol with a spirocyclic acetal structure, starting from bio-based vanillin and pentaerythritol. According to a preliminary life cycle assessment (LCA), the greenhouse gas emissions of this bio-based diol are significantly lower than that of bio-based 1,3-propanediol. Copolymerization of the rigid spiro-diol with 1,6-hexanediol and dimethyl terephthalate by melt polymerization yielded a series of copolyesters, which showed improved glass transition temperature and thermal stability upon the incorporation of the spiro-acetal units. The crystallinity and melting point of copolyesters decreased with increasing content of the spirocyclic backbone structures. The copolyesters containing 10% of the new diol was semicrystalline while those with 20 and 30% spiro-diol incorporated were completely amorphous. Moreover, dynamic mechanical analysis indicated that the copolyesters showed comparable storage moduli as AkestraTM, a commercial fossil-based high-performance polyester.
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| 3. |
- Rodriguez Arza, Carlos, et al.
(författare)
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Synthesis, thermal, rheological characteristics, and enzymatic degradation of aliphatic polyesters with lignin‐based aromatic pendant groups
- 2019
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Ingår i: Journal of Polymer Science. Part A, Polymer Chemistry. - : Wiley. - 0887-624X .- 1099-0518. ; 57:23, s. 2314-2323
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Tidskriftsartikel (refereegranskat)abstract
- This research aims to produce lignin‐based biodegradable polyesters with improved thermal quality. A series of aliphatic polyesters with lignin‐based aromatic side groups were synthesized by conventional melt‐polycondensation. Decent molecular weight (21–64 kg mol−1) was achieved for the polymerizations. The molecular structures and thermal and mechanical properties of the obtained polyesters were characterized. As a result, the obtained polyesters are all amorphous, and their glass‐transition temperature (Tg) depends on the size of the pendant aromatic group (31–51 °C). Furthermore, according to the TGA results, the thermal decomposition temperatures of the polyesters are all above 390 °C, which make them superior compared with commercial biodegradable polyesters like polylactic acid or polyhydroxyalkanoates. Finally, rheological characteristics and enzymatic degradation of the obtained polyesters were also measured.
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| 4. |
- Warlin, Niklas, et al.
(författare)
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A rigid spirocyclic diol from fructose-based 5-hydroxymethylfurfural: synthesis, life-cycle assessment, and polymerization for renewable polyesters and poly(urethane-urea)s
- 2019
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Ingår i: Green Chemistry. - 1463-9270. ; 21:24, s. 6667-6684
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Tidskriftsartikel (refereegranskat)abstract
- There is currently an intensive development of sugar-based building blocks toward the production of renewable high performance plastics. In this context, we report on the synthesis of a rigid diol with a spirocyclic structure via a one-step acid-catalyzed acetalation of fructose-sourced 5-hydroxymethylfurfural and pentaerythritol. Preliminary life cycle assessment (LCA) indicated that the spiro-diol produced 46% less CO2 emission than bio-based 1,3-propanediol. Polymerizations of the spiro-diol together with another sugar-based flexible 1,6-hexanediol for the production of polyesters and poly(urethane-urea)s were investigated, and reasonably high molecular weights were achieved when up to 20 or 60 mol% spiro-diol was used for polyesters or poly(urethane-urea)s, respectively. The glass transition temperatures (Tg) of the polyesters and poly(urethane-urea)s significantly increased upon the incorporation of the rigid spirocyclic structure. On the other hand, it was observed that the spiro-diol was heat-sensitive, which could cause coloration andpartial crosslinking when >10%(with respect to dicarboxylate) was used for the polyester synthesis at high temperatures.The results indicated that the polymerization conditions have to be carefully controlled in order to avoid coloration and side reactions during the polyester formation when >10% of the spiro-diol is used. However, when the spiro-diol was used for the synthesis of polyurethanes at lower temperature, the side reactions were insignificant. This suggests that the new spiro-diol can be potentially suitable toward the production of sustainable rigid polyurethane materials like coatings or foams, as well as renewable polyesters after further optimization of the polymerization conditions.
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