Lignosulfonate-Based Polyurethane Adhesives

abstract

The feasibility of using lignosulfonate (LS) from acid sulphite pulping of eucalyptus wood as an unmodified polyol in the formulation of polyurethane (PU) adhesives was evaluated. Purified LS was dissolved in water to simulate its concentration in sulphite spent liquor and then reacted with 4,4 & PRIME;-diphenylmethane diisocyanate (pMDI) in the presence or absence of poly(ethylene glycol) with M-w 200 (PEG(200)) as soft crosslinking segment. The ensuing LS-based PU adhesives were characterized by infrared spectroscopy and thermal analysis techniques. The adhesion strength of new adhesives was assessed using Automated Bonding Evaluation System (ABES) employing wood strips as a testing material. The results showed that the addition of PEG(200) contributed positively both to the homogenization of the reaction mixture and better crosslinking of the polymeric network, as well as to the interface interactions and adhesive strength. The latter was comparable to the adhesive strength recorded for a commercial white glue with shear stress values of almost 3 MPa. The optimized LS-based PU adhesive formulation was examined for the curing kinetics following the Kissinger and the Ozawa methods by non-isothermal differential scanning calorimetry, which revealed the curing activation energy of about 70 kJ & BULL;mol(-1).

keywords

KRAFT LIGNIN; CASTOR-OIL; CURING KINETICS; CRUDE GLYCEROL; FOAMS; FORMALDEHYDE; CALIBRATION; WOOD

subject category

Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Physics, Applied; Physics, Condensed Matter

authors

Magina, S; Gama, N; Carvalho, L; Barros-Timmons, A; Evtuguin, DV

our authors

acknowledgements

This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology (FCT)/Ministry of Science, Technology and Higher Education (MCTES), base FundingUIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology and EnergyLEPABEfunded by national funds through the FCT/MCTES (PIDDAC) and funded by FCT and the European Social Fund (ESF) within the framework of PORTUGAL2020, namely through the Programa Operacional Regional do Centro (Centro 2020) (PhD grant SFRH/BD/121275/2016).

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