Lignin-based polyurethane and epoxy adhesives: a short review

Purpose: of this paper was to review and summarize significant papers related to the development and characterization of lignin-containing adhesives: polyurethane and epoxy types. In the last decades, several efforts have been dedicated on the development of renewable raw materials for polymer synthesis, mainly due to petroleum depletion and sustainability. In this context, lignin emerged as a potential candidate to substitute fossil-based raw materials in adhesive synthesis and formulations. Design/methodology/approach: Recent and other relevant papers were reviewed, aiming to identify the main advantages and limitations involved in lignin incorporation into epoxy and polyurethane adhesives formulations. First, effects of unmodified lignin addition were presented. Afterwards, the main lignin chemical modification methods were presented and discussed, based on thermomechanical results. Findings: Incorporation of unmodified lignin usually is limited to 30 %wt., otherwise mechanical properties are drastically affected as consequence of poor lignin solubility and excessive brittleness. Lignin chemical modification can be used to increase the reactivity of hydroxyl groups and/or add new moieties in its molecular structure, improving solubility and thermomechanical properties of cured adhesives. Practical implications: In the last years, some industrial plants started to operate and produce technical grade lignin at industrial scale, with reproducible properties and controlled molecular structure. Therefore, increasing efforts have been dedicated from researchers and chemists to develop lignin-based technologies, in which this work can directly contribute with. Originality/value: As consequence of the high content of phenol groups in its molecular structure, lignin was mostly applied on the development of phenolic resins applied as wood adhesives. For the first time in the literature, this work summarizes the advances related to synthesis and characterization of polyurethane and epoxy, applied as adhesives. Results can support the development and application of biobased, as well as contribute to the revalorization of this valuable and readily available biomass

Fenologia de Lafoensia pacari A.St.-Hil. (Lythraceae) em Barra do Garças, Mato Grosso, Brasil Phenology of Lafoensia pacari A.St.-Hil. (Lythraceae) in Barra do Garças, Mato Grosso State, Brazil

Lafoensia pacari A.St.-Hil. é uma espécie da flora do cerrado usada na medicina popular como anti-úlcera, antifúngica, antibactericida, anti-inflamatória, febrífuga, para emagrecimento e no tratamento de pneumonia, dores de estômago e coceiras. Estudou-se a fenologia de L. pacari no cerrado do Parque Estadual da "Serra Azul", região de Barra do Garças-MT (15º 51' 58" S e 52º 15' 37" W), à 645 m de altitude, durante o período de 24 meses. Verificou-se que as fenofases são sazonais, com floração nos meses de abril a agosto, frutificação de junho a setembro, brotação no início da estação chuvosa de outubro a dezembro e queda de folhas de julho a setembro, no final da estação seca.<br>Lafoensia pacari is a species from the Brazilian cerrado used in folk medicine to control ulcers, fungal and bacterial diseases, inflammations, fevers, pneumonia, stomachaches, and itching, as well as to lose weight. L. pacari phenology was studied for 24 months in the cerrado at "Serra Azul" State Park, in the region of Barra do Garças, Mato Grosso State, Brazil (15º 51' 58" S and 52º 15' 37" W), at 645 m altitude. Phenophases are seasonal, with flowering from April to August, fruiting from June to September, sprouting from October to December, during the beginning of the rainy season, and leaf fall from July to September, at the end of the dry season