Color and Gloss Changes of a Lignin-Based Polyurethane Coating under Accelerated Weathering

• The purpose of this research study was to investigate the properties of polyurethane coatings based on ligninnano-particles. For this purpose, the prepared coatings were applied to pine wood surfaces and weathered artificially.Subsequently, color and gloss of the coatings were measured before and after the weathering test. Fieldemission scanning electron microscopy (FE-SEM) micrographs prepared from the coatings showed that the averagesize of nano-particles in the polyurethane substrate was approximately 500 nm. Nuclear magnetic resonance(13C-NMR) spectroscopy showed that strong urethane bonds were formed in the nano-lignin-based polyurethane.Differential calorimetric analysis (DSC) test revealed that the glass-transition temperature (Tg) of lignin nanoparticlesmodified with diethylenetriamine (DETA) was 112.8°C and Tg of lignin nano-particles modified withethylenediamine (EDA) was 102.5°C, which is lower than the Tg of un-modified lignin (114.6°C) and lignin modifiedwith DETA (126.8°C) and lignin modified with EDA (131.3°C). The coatings modified with lignin nano-particleshad a greater change in gloss. The lignin nano-particles in the modified coating are trapping hydroxylradicals which reduces photoactivity and yellowing of the polyurethane by about 3 times compared to unmodifiedpolyurethane coatings. After weathering test, the nano-lignin-based coating had a rougher surface with a lowercontact angle (0.78°) compared to the unmodified polyurethane coating (0.85°).

Ämnesord

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Trävetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Wood Science (hsv//eng)

Nyckelord

Amination

propylene carbonate

lignin

biopolymer

polyurethane

coating

polyol

UN SDG 13

Träteknik

Wood Science and Engineering

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)