126 research outputs found
Dual-Templating Approach for Engineering Strong, Biodegradable Lignin-Based Foams
Technical lignins are generated as
byproducts from the wood pulping
industry. Although their estimated annual production amounts to approximately
70 million tons, their exploitation as value-added products remains
insignificant. Yet, the diversity in the molecular structure and surface
chemistry of technical lignins and their intrinsic role as mechanical
support of plants may be an asset to consider in the engineering of
plant-inspired materials such as biofoams. Valorization of lignins
into solid foams, however, rarely accounts for more than 45–50
wt % of lignins because of their brittle nature. Herein, we report
a strategy to develop fully biodegradable lignin-based foams of high
stiffness, strength, and toughness that are comparable to, or in some
cases exceed, the performance of petroleum-derived foams. A dual-templating
approach using ice and cellulose nanofibrils (CNFs) as templates was
selected to control the porous architecture of the foams made by the
assembly of lignin and cellulose in the cell walls. Foams with varying
lignin-to-CNF weight ratios showed enhanced structural and mechanical
integrity compared with neat lignin and CNF foams. For 80–90
wt % of lignin, a significant increase (+50%) in the foams’
compressive performance was observed. Varying the degree of sulfonation
of lignin and in turn its chemical interaction with cellulose enabled
the generation of biodegradable composite foams with tunable compressive
strength. The greater the colloidal stability of the lignin-CNF suspension,
the higher the foams’ compressive performance. This study thus
discusses an engineering approach for the valorization of technical
lignins into sustainable foams that have potential as packaging materials
and sandwich panels, in which high stiffness, strength, and toughness
per unit weight are required
Design strategies, properties and applications of cellulose nanomaterials-enhanced products with residual, technical or nanoscale lignin—A review
With the increasing demand for greener alternatives to fossil-derived products, research on cellulose nanomaterials (CNMs) has rapidly expanded. The combination of nanoscale properties and sustainable attributes makes CNMs an asset in the quest for a sustainable society. However, challenges such as the hydrophilic nature of CNMs, their low compatibility with non-polar matrices and modest thermal stability, slow the development of end-uses. Combination of CNMs with amphiphilic lignin can improve the thermal stability, enhance the compatibility with non-polar matrices and, additionally, endow CNMs with new functionalities e.g., UV shielding or antioxidative properties. This article comprehensively reviews the different design strategies and their influence on properties and applications of CNMs containing lignin in various forms; either as residual lignin, added technical lignin, or nanoscale particles. The review focuses especially on the synergy created between CNMs and lignin, paving the way for new production routes and use of CNM/lignin materials in high-performance applications.Peer reviewe
Conclusion and future trends
Bio-based polymers are rapidly emerging as sustainable alternatives to conventional synthetic and petroleum-based materials, being highly desired in many diverse areas for high-value applications. These materials could indeed be an answer to society regarding filling some lacks in the most diverse sectors, such as food packaging industry. It is expected that in the future, the innovation on the use of lignocellulosic materials in bio-based packaging will range from the extraction and purification of the lignocellulosic materials to the type of application where these materials are used (i.e. active and intelligent packaging).info:eu-repo/semantics/publishedVersio
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