Lignin-Based Phenols: Potential Feedstock for Renewable Benzoxazines
01 Jan 2017-pp 473-498
TL;DR: In this paper, the major phenolic components available from lignin and its utility as a synthon for benzoxazine monomer synthesis are discussed and a discussion of its utility in various applications is presented.
Abstract: Lignin is an amorphous biopolymer consisting of hydroxyphenyl propane units, which are interlinked with ether and biphenyl linkages. The widespread abundance and variation in the substitution of phenolic units in the nature of plant species present them as a viable source for phenolic raw materials. This chapter aims to list the major phenolic components available from lignin and its utility as a synthon for benzoxazine monomer synthesis. The presence of additional functionalities in the monomer dictates the polymer properties and its utility in various applications.
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TL;DR: In this article, the authors demonstrate the utility of incorporating biobased benzoxazines into benzoxazine-epoxy resin formulations to design sustainable polybenzoxazines with tunable thermal and mechanical properties for high-performance polymer applications.
Abstract: Biobased polybenzoxazines incorporate natural phenolic structures to produce polymers with near-zero shrinkage, high char yields, and high chemical and thermal resistances, garnering great interest as sustainable high-performance polymers. Herein, difunctional and trifunctional benzoxazine monomers, bisguaiacol-furfurylamine (BG-f) and triguaiacol-furfurylamine (TG-f), respectively, were synthesized from renewable guaiacol, vanillin, and furfurylamine using solventless procedures. Benzoxazines were blended with varying weights of epoxy resin and thermally cured to produce benzoxazine-epoxy (BG-f-E and TG-f-E) polymers. These polymers displayed glass transition temperatures ranging from 130 to 157 °C (peak of the loss modulus), thermal stabilities from 299 to 329 °C in both N₂ and air, and char yields ranging from 35% to 58%. BG-f-E and TG-f-E with greater benzoxazine content produced stiffer materials exhibiting glassy storage moduli values upward of 3.48 and 3.69 GPa, respectively. BG-f-E polymers displayed higher molecular weight between cross-link values (646 g mol–¹ to 981 g mol–¹) compared to TG-f-E polymers (316 g mol–¹ to 465 g mol–¹) and exhibited fracture energies upward of 404 J m–². These investigations demonstrate the utility of incorporating biobased benzoxazines into benzoxazine-epoxy resin formulations to design sustainable polybenzoxazines with tunable thermal and mechanical properties for high-performance polymer applications.
23 citations
TL;DR: The setup of a simple screening strategy for useful epoxidases is reported, which provides access to drug-like molecules and technically relevant synthesis precursors in processing of lignin.
Abstract: Processing of lignin provides access to mono-aromatic compounds with a styrene-like structure. The vinyl sidechain can be attacked by monooxygenases, such as styrene or indole monooxygenases, to yield enantiopure epoxides. The obtained epoxides can be converted into valuable products, either enzyme- or non-enzyme driven. This provides access to drug-like molecules and technically relevant synthesis precursors. Herein, we report the setup of a simple screening strategy for useful epoxidases.
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TL;DR: In this article, a review of the progress to date in the field of mechanical reinforcement of polymers using nanotubes is presented, and the most promising processing methods for mechanical reinforcement are discussed.
3,770 citations
TL;DR: In this article, a review of polymer nanocomposites with single-wall or multi-wall carbon nanotubes is presented, and the current challenges to and opportunities for efficiently translating the extraordinary properties of carbon-nanotubes to polymer matrices are summarized.
Abstract: We review the present state of polymer nanocomposites research in which the fillers are single-wall or multiwall carbon nanotubes. By way of background we provide a brief synopsis about carbon nanotube materials and their suspensions. We summarize and critique various nanotube/polymer composite fabrication methods including solution mixing, melt mixing, and in situ polymerization with a particular emphasis on evaluating the dispersion state of the nanotubes. We discuss mechanical, electrical, rheological, thermal, and flammability properties separately and how these physical properties depend on the size, aspect ratio, loading, dispersion state, and alignment of nanotubes within polymer nanocomposites. Finally, we summarize the current challenges to and opportunities for efficiently translating the extraordinary properties of carbon nanotubes to polymer matrices in hopes of facilitating progress in this emerging area.
3,239 citations
TL;DR: There are several methods for the dispersion of CNTs in the polymer matrix such as solution mixing, melt mixing, electrospinning, in-situ polymerization and chemical functionalization of the carbon nanotubes as discussed by the authors.
1,503 citations
TL;DR: In this paper, it was shown that the amount of char and the incombustible gases that may be formed in thermal decomposition are very important quantitative measures of flame resistance.
855 citations
TL;DR: For value-added applications of lignin to be improved, medium- and long-term conversion technologies must be developed, especially for the preparation of low-molecular-weight compounds as an alternative to the petrochemical industry.
Abstract: Lignin is by far the most abundant substance based on aromatic moieties in nature, and the largest contributor to soil organic matter. Millions of tonnes of several lignin preparations are produced by the paper industry every year, and a minimal amount of lignin is isolated by direct extraction of lignin from plants. Lignin is used either directly or chemically modified, as a binder, dispersant agent for pesticides, emulsifier, heavy metal sequestrant, or component for composites and copolymers. For value-added applications of lignin to be improved, medium- and long-term conversion technologies must be developed, especially for the preparation of low-molecular-weight compounds as an alternative to the petrochemical industry.
773 citations