Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks
The hydrophilic extractives isolated from black alder (<i>Alnus glutinosa</i>) bark through hot water extraction were characterized as novel renewable macromonomers capable of forming polyurethane (PU) networks based on a commercial polyisocyanate, with partial or complete replacement of...
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| Format: | Article |
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MDPI AG
2023-08-01
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| Series: | Polymers |
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| Online Access: | https://www.mdpi.com/2073-4360/15/17/3503 |
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| author | Alexandr Arshanitsa Jevgenija Ponomarenko Matiss Pals Lilija Jashina Maris Lauberts |
| author_facet | Alexandr Arshanitsa Jevgenija Ponomarenko Matiss Pals Lilija Jashina Maris Lauberts |
| author_sort | Alexandr Arshanitsa |
| collection | DOAJ |
| description | The hydrophilic extractives isolated from black alder (<i>Alnus glutinosa</i>) bark through hot water extraction were characterized as novel renewable macromonomers capable of forming polyurethane (PU) networks based on a commercial polyisocyanate, with partial or complete replacement of petroleum-derived polyol polyether. The bark-sourced bio-polyol mainly consists of the xyloside form of the diarylheptanoid oregonin, along with oligomeric flavonoids and carbohydrates, resulting in a total OH group content of 15.1 mmol·g<sup>−1</sup> and a molecular weight (M<sub>n</sub>) of approximately 750 g∙mol<sup>−1</sup>. The <sup>31</sup>P NMR data confirmed a similar proportion of aliphatic OH and phenolic groups. Three-component PU compositions were prepared using polyethylene glycol (M<sub>n</sub> = 400 g∙mol<sup>−1</sup>), bio-polyol (up to 50%), and polymeric diphenylmethane diisocyanate, which were pre-polymerized in tetrahydrofuran (THF) solution with tin organic and tertiary amine catalysts. The resulting mixture was cast and subjected to thermal post-curing. Calculation and experimental data confirmed the crosslinking activity of the bark-sourced bio-polyol in PU, leading to an increase in glass transition temperature (Tg), a decrease in sol fraction yield upon leaching of cured PU networks in THF, a significant increase in Young’s modulus and tensile strength. The macromonomers derived from bark promoted char formation under high temperature and oxidative stress conditions, limiting heat release during macromolecular network degradation compared to bio-polyol-free PU. It was observed that amine catalysts, which are active in urethane formation with phenolic groups, promoted the formation of PU with higher Tg and modulus at tensile but with less limitation of heat liberation during PU macromolecular structure degradation. The high functionality of the bark-derived bio-polyol, along with the equal proportion of phenolic and aliphatic OH groups, allows for further optimization of PU characteristics using three variables: increasing the substitution extent of commercial polyethers, decreasing the NCO/OH ratio, and selecting the type of catalyst used. |
| first_indexed | 2024-03-10T23:15:50Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2073-4360 |
| language | English |
| last_indexed | 2024-03-10T23:15:50Z |
| publishDate | 2023-08-01 |
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| series | Polymers |
| spelling | doaj.art-daa4824eeba448e8b9d2ca098520b1f12023-11-19T08:42:30ZengMDPI AGPolymers2073-43602023-08-011517350310.3390/polym15173503Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane NetworksAlexandr Arshanitsa0Jevgenija Ponomarenko1Matiss Pals2Lilija Jashina3Maris Lauberts4Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, LV-1006 Riga, LatviaLatvian State Institute of Wood Chemistry, Dzerbenes Street 27, LV-1006 Riga, LatviaLatvian State Institute of Wood Chemistry, Dzerbenes Street 27, LV-1006 Riga, LatviaLatvian State Institute of Wood Chemistry, Dzerbenes Street 27, LV-1006 Riga, LatviaLatvian State Institute of Wood Chemistry, Dzerbenes Street 27, LV-1006 Riga, LatviaThe hydrophilic extractives isolated from black alder (<i>Alnus glutinosa</i>) bark through hot water extraction were characterized as novel renewable macromonomers capable of forming polyurethane (PU) networks based on a commercial polyisocyanate, with partial or complete replacement of petroleum-derived polyol polyether. The bark-sourced bio-polyol mainly consists of the xyloside form of the diarylheptanoid oregonin, along with oligomeric flavonoids and carbohydrates, resulting in a total OH group content of 15.1 mmol·g<sup>−1</sup> and a molecular weight (M<sub>n</sub>) of approximately 750 g∙mol<sup>−1</sup>. The <sup>31</sup>P NMR data confirmed a similar proportion of aliphatic OH and phenolic groups. Three-component PU compositions were prepared using polyethylene glycol (M<sub>n</sub> = 400 g∙mol<sup>−1</sup>), bio-polyol (up to 50%), and polymeric diphenylmethane diisocyanate, which were pre-polymerized in tetrahydrofuran (THF) solution with tin organic and tertiary amine catalysts. The resulting mixture was cast and subjected to thermal post-curing. Calculation and experimental data confirmed the crosslinking activity of the bark-sourced bio-polyol in PU, leading to an increase in glass transition temperature (Tg), a decrease in sol fraction yield upon leaching of cured PU networks in THF, a significant increase in Young’s modulus and tensile strength. The macromonomers derived from bark promoted char formation under high temperature and oxidative stress conditions, limiting heat release during macromolecular network degradation compared to bio-polyol-free PU. It was observed that amine catalysts, which are active in urethane formation with phenolic groups, promoted the formation of PU with higher Tg and modulus at tensile but with less limitation of heat liberation during PU macromolecular structure degradation. The high functionality of the bark-derived bio-polyol, along with the equal proportion of phenolic and aliphatic OH groups, allows for further optimization of PU characteristics using three variables: increasing the substitution extent of commercial polyethers, decreasing the NCO/OH ratio, and selecting the type of catalyst used.https://www.mdpi.com/2073-4360/15/17/3503barkmacromonomerphenolic groupsaliphatic OHpolyurethane networktensile properties |
| spellingShingle | Alexandr Arshanitsa Jevgenija Ponomarenko Matiss Pals Lilija Jashina Maris Lauberts Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks Polymers bark macromonomer phenolic groups aliphatic OH polyurethane network tensile properties |
| title | Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks |
| title_full | Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks |
| title_fullStr | Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks |
| title_full_unstemmed | Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks |
| title_short | Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks |
| title_sort | impact of bark sourced building blocks as substitutes for fossil derived polyols on the structural thermal and mechanical properties of polyurethane networks |
| topic | bark macromonomer phenolic groups aliphatic OH polyurethane network tensile properties |
| url | https://www.mdpi.com/2073-4360/15/17/3503 |
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