Chemical modification of lignins: Towards biobased polymers

Our severe dependence on fossil resources for the production of fuels and chemicals is responsible for two major global challenges: declining the fuel supply and increasing the anthropogenic greenhouse gas emissions. Conversion of biomass to fuels and chemicals can be a part of the low-carbon solution to both issues. Among various biomass species, inedible biomass such as lignocellulosics is the preferred choice for such applications due to their minimal impact on the food security. While technologies for the conversion of carbohydrates to value-added materials such as pulp, sugar monomers, and ethanol are well-established, lignin upgrading and valorization processes are significantly less-developed, and technical lignins are almost entirely burnt to generate heat and steam. The economic viability of biorefineries – which will receive significant amounts of lignin in future – can potentially improve significantly when advanced technologies are available that aid the conversion of lignin to value-added compounds. In this paper we assess how thermochemical processes can be used to isolate lignin from the lignocellulosic biomass, and subsequently convert it to liquid fuels, hydrogen, and aromatic monomers. To this end, different depolymerization, gasification and upgrading technologies for lignin conversion will be considered. Finally, the foreseeable applications of lignin-based products, the future directions for development, and the potential supportive interventions from policy makers are critically assessed.

Liquid fuels, hydrogen and chemicals from lignin: A critical review

Value-adding to cellulosic ethanol: lignin polymers.

Impact of torrefaction on the grindability and fuel characteristics of forest biomass.

Lignin in straw of herbaceous crops

Structural characterization of technical lignins for the production of adhesives: Application to lignosulfonate, kraft, soda-anthraquinone, organosolv and ethanol process lignins

Analytical methods for determining functional groups in various technical lignins

Lignin-based wood adhesives prepared without formaldehyde substituted by non-volatile non-toxic aldehyde, namely glyoxal, were prepared and tested for application to wood panels such as particleboard. The adhesives yielded good IB strength results of the panels, enough to comfortably pass relevant international standard specifications for exterior-grade panels. The adhesives also showed sufficient reactivity to yield panels in press times comparable to those of formaldehyde-based commercial adhesives.

Lignin-based wood panel adhesives without formaldehyde

Stone groundwood (SGW) is a fibrous matter commonly prepared in a high yield process, and mainly used for papermaking applications. In this work, the use of SGW fibers is explored as reinforcing element of polypropylene (PP) composites. Due to its chemical and superficial features, the use of coupling agents is needed for a good adhesion and stress transfer across the fiber-matrix interface. The intrinsic strength of the reinforcement is a key parameter to predict the mechanical properties of the composite and to perform an interface analysis. The main objective of the present work was the determination of the intrinsic tensile strength of stone groundwood fibers. Coupled and non-coupled PP composites from stone groundwood fibers were prepared. The influence of the surface morphology and the quality at interface on the final properties of the composite was analyzed and compared to that of fiberglass PP composites. The intrinsic tensile properties of stone groundwood fibers, as well as the fiber orientation factor and the interfacial shear strength of the current composites were determined.

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Mean intrinsic tensile properties of stone groundwood fibers from softwood

Currently, acoustic isolation is one of the problems raised with building construction in Spain. The publication of the Basic Document for the protection against noise of the Technical Building Code has increased the demand of comfort for citizens. This has created the need to seek new composite materials that meet the new required acoustical building codes. In this paper we report the results of the newly developed composites that are able to improve the acoustic isolation of airborne noise. These composites were prepared from polypropylene (PP) reinforced with mechanical pulp fibers from softwood (Pinus radiata). Mechanical and acoustical properties of the composites from mechanical pulp (MP) and polypropylene (PP) have been investigated and compared to fiberglass (FG) composites. MP composites had lower tensile properties compared with FG composites, although these properties can be improved by incorporation of a coupling agent. The results of acoustical properties of MP composites were reported and compared with the conventional composites based on fiberglass and gypsum plasterboards. Finally, we suggest the application of MP composites as a light-weight building material to reduce acoustic transmitions.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_07_4_4586_Lopez_Acoustic_Properties_Polypropylene_Composite_Groundwood/1707

Nour-Eddine El Mansouri

Papers

Structural characterization of technical lignins for the production of adhesives: Application to lignosulfonate, kraft, soda-anthraquinone, organosolv and ethanol process lignins

Analytical methods for determining functional groups in various technical lignins

Lignin-based wood panel adhesives without formaldehyde

Mean intrinsic tensile properties of stone groundwood fibers from softwood

Acoustic properties of polypropylene composites reinforced with stone groundwood