The irruption of polymers from renewable resources on the scene of macromolecular science and technology

https://pubs.rsc.org/en/content/articlepdf/2015/gc/c5gc00282f

Chemical modification of tannins to elaborate aromatic biobased macromolecular architectures

The annual bark yield in Canada is as much as 17 million m3. Currently, more than half of the bark is incinerated or landfilled and the remainder of the bark is mainly used as a cheap source of energy in saw/pulp mills. Both bark incineration and landfilling can lead to environmental problems. Due to the abundance of ash in bark and the lower sintering point of bark ash than that of wood ash, the combustion of bark can lead to fouling which would damage the combustors. Bark contains a large fraction of extractives and lignin (up to 50 wt% on a dry basis), which can be utilized as a renewable source of chemicals, particularly aromatic chemicals. The technical routes and technologies on the valorization of tree barks for chemicals and materials are reviewed in this paper. These include direct utilization of bark for wooden panels, and extraction for extractives (mainly tannin) and their the application in resins and foam materials, as well as conversion of bark via thermochemical technologies, mainly phenolysis, direct liquefaction in alcohols and pyrolysis. Finally, some challenges and perspectives on the production of chemicals and materials from bark are discussed.

Valorization of bark for chemicals and materials: A review

Green chemistry for and from wood has developed numerous industrial products, namely biosourced, green wood adhesives and preservatives, foams, composite matrices, laminates, hard and flexible plastics, flexible films, and abrasive grinding discs, and their number is still growing. This review addresses (1) the elimination of toxic aldehydes from the most common wood panel adhesive, the one based on urea, itself a natural product, (2) biosourced adhesives derived from wood or other vegetable matter and used for wood products, and (3) wood and bark tannin-based foams, natural fiber composites using tannin matrices, paper surface laminates and continuous high-pressure paper laminates using tannin-furanics, hard plastics based on tannin-furanic materials and some of their applications, flexible biosourced tannin-furanic films, and biosourced wood preservatives.

/pdf/wood-products-and-green-chemistry-cyjq5wcg9y.pdf

Wood products and green chemistry

https://aaltodoc.aalto.fi/bitstream/handle/123456789/15348/article3.pdf?sequence=4

G. Du

Papers

Tannin-based rigid foams: a survey of chemical and physical properties.