Chemical and radiation-chemical radical reactions in lignocellulose materials

Kuzina, S. I.; Shilova, I. A.; Михайлов, А. И.

doi:10.1016/j.radphyschem.2011.04.005

Cited by 15 publications

(15 citation statements)

References 10 publications

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“…7 Composition of the benzenediols series in the tar formed via three modes of dry distillation. DD conventional dry distillation of lignin, EBD radiation-assisted dry distillation of lignin, EBDW radiation-assisted dry distillation of lignin/wax mixture radical and a fragment of the macromolecule with a protonated polar group should be considered as a key reaction scheme of the primary radiolytic transformations of lignin [11][12][13][14].…”

Section: Resultsmentioning

confidence: 99%

“…The conversion of the radical anion into the H adduct is simplified due to the presence of acids among the products of lignin radiolysis (for example, acetic acid). Structurally similar adducts result from the addition of H atoms to the aromatic units of lignin [12][13][14]: Typically, the aromatic radical is thermally degraded by cleavage of the bond in the β-position relative to the benzene ring [11][12][13]. The methoxy O-CH 3 bond is in the β-position.…”

Section: Resultsmentioning

confidence: 99%

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Thermopolymerization inhibitors generated via radiolysis of lignin

et al. 2018

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The pyrogenic conversion of lignin to a phenolic tar can be significantly enhanced by combining dry distillation with simultaneous electron-beam treatment of lignin. The tar produced by the combined method contains three times more benzenediols in comparison with conventional pyrogenic distillation method. As shown, the tar of radiation-thermal origin can inhibit the thermopolymerization of certain monomers, such as styrene. The inhibiting ability of tar exceeds that of synthetic phenolic inhibitors. In the presence of 0.025 wt% of the tar, the induction period of styrene thermopolymerization at 120 °С is at least 120 min. Radiation-thermal formation of phenolic tar obeys the chain mechanism and thereby, is a highly efficient process.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Thermopolymerization inhibitors generated via radiolysis of lignin

et al. 2018

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“…Acetic anhydride treatment leads to further modification of fiber surface, which becomes hydrophobic so that the adhesion between the fibers and the polymer matrix increases . Both modifications result in generation of free radicals . Similarly, thermal and mechanical treatment of composites which contain lignocellulose materials may result in breaking of chemical bonds, filler, and polypropylene main‐chain scissions and free radicals generation…”

Section: Resultsmentioning

confidence: 99%

Recycling of lignocellulosics filled polypropylene composites. I. Analysis of thermal properties, morphology, and amount of free radicals

Paukszta

Markiewicz

Ostrowski

et al. 2014

J of Applied Polymer Sci

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Composites of isotactic polypropylene filled with comminuted rapeseed straw are studied. Improvement in interfacial adhesion is achieved by chemical modification of the lignocellulose filler. Composites were subjected to recycling by extrusion. The effect of multiple recycling of the composites on the process of nucleation and crystallization of polypropylene matrix, surface topography, and free radical generation was checked. On the basis of differential scanning calorimetry data, a significant influence of the recycling on nucleation activity of the lignocellulose filler was evidenced. A relation between the filler particle size and multiple recycling was established by observations under a polarization microscope, while scanning electron microscope analyses confirmed the positive effect of chemical modification of rapeseed straw on the interfacial adhesion. The composite structure changes forced by multiple recycling are discussed in the context of free radical generation. Concentration of free radicals in the rapeseed straw samples and composites was measured by the electron paramagnetic resonance spectroscopy to show that it was higher in the systems subjected to multiple recycling. Interestingly, the composites after multiple recycling showing elevated concentration of free radicals are also characterized by higher nucleation activity.

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“…Lignin polymerization begins with the oxidation of the phenyl-propane hydroxyl groups (Kuzina et al 2011). The lignin precursors undergo dimerization through enzymatic dehydrogenation, which is initiated by electron transfer and yields resonance-stabilized phenoxy radicals (Chen et al 2006;Vanholme et al 2012;Zhang et al 2012).…”

Section: Lignin Polymerizationmentioning

confidence: 99%

Laccase, an Emerging Tool to Fabricate Green Composites: A Review

Mahmood¹,

Hashim²,

Sulaiman³

et al. 2015

BioResources

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In the last two decades, laccases have received much attention from researchers because of their specific ability to oxidize lignin. This function of laccase is very useful for applications in several biotechnological processes, including delignification in the pulp and paper industry and the detoxification of industrial effluents from the textile and petrochemical industries. This review focuses on laccase-mediated fiberboard synthesis. Growing concerns regarding the emission of formaldehyde from wood composites has prompted industrialists to consider the fabrication of green composites. Laccase-mediated fiber treatments oxidize the lignin component without affecting the cellulose structure. As a result, free radicals are generated on the fiber surface, and these can act as potential reactive sites for further cross-linking reactions in board manufacturing. Binderless fiberboards prepared using such methods can be considered as green composites because the manufacturing process involves no additional resin.

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Chemical and radiation-chemical radical reactions in lignocellulose materials

Cited by 15 publications

References 10 publications

Thermopolymerization inhibitors generated via radiolysis of lignin

Thermopolymerization inhibitors generated via radiolysis of lignin

Recycling of lignocellulosics filled polypropylene composites. I. Analysis of thermal properties, morphology, and amount of free radicals

Laccase, an Emerging Tool to Fabricate Green Composites: A Review

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