Structure characterization of films from drying oils cured under infrared light

Abstract

Drying oils have been considered as water resistant coatings for bio-based packaging materials; however, their curing rates are slow for industrial applications. Infrared radiation was investigated in this study as a means to increase the curing rate of linseed and tung oils. The effect of oil pretreatment with gamma radiation was also investigated. FTIR spectroscopy was used to monitor chemical changes during oil oxidation. Results indicated that infrared radiation increased the curing rate of linseed and tung oils. The oxidation rate of both oils, as monitored by the decrease of the 3010 cm À1 FTIR peak, followed an exponential decay. The structure of cured films was examined by SEM. Images of films cross section were used to develop a qualitative model of the curing process. Linseed and tung oil showed differences in structural development during drying. In the case of linseed oil, the formation of a tough skin layer slowed down oxygen diffusion to the oil underneath, resulting in slow curing. For the case of tung oil, the skin layer shrank as it formed allowing oxygen diffusion and fast curing of tung oil.

Tung Oil Wood Finishes with Improved Weathering, Durability, and Scratch Performance by Addition of Cellulose Nanocrystals

“…This characteristic results in much faster drying than other oils, generating high resistance against mixture penetration and hydrolysis. Therefore, for thick coatings, this fast-oxidative curing leads to the formation of a solid skin layer (acting as a diffusion barrier to atmospheric oxygen), while TO is still viscous under this thin skin . Consequently, poor through-drying is one of the major drawbacks of drying oils because the following curing of oil under the skin layer will generate tension at the interface which may bring about a characteristic “frosted” or “blistering” appearance (having a skinning tendency and wrinkled finish).…”

“…Therefore, for thick coatings, this fast-oxidative curing leads to the formation of a solid skin layer (acting as a diffusion barrier to atmospheric oxygen), while TO is still viscous under this thin skin. 40 Consequently, poor through-drying is one of the major drawbacks of drying oils because the following curing of oil under the skin layer will generate tension at the interface which may bring about a characteristic "frosted" or "blistering" appearance (having a skinning tendency and wrinkled finish). This property may be soothed by adding hCNC to TO as an oxygen gas barrier, which would act to control the drying rate of the nanocomposite coatings.…”

Effect of Microwave Cure on the Thermo-Mechanical Properties of Tung Oil-Based/Carbon Nanotube Composites

“…Recently, the alternative Infra-red curing of tung oil films has been investigated [22]. In unrelated applications, tung oil has been employed as a promising starting material for the preparation of biodiesel [23].…”

Uporaba naravnih olj za površinsko zaščito lesa navadne bukve

“…Na splošno lahko rečemo, da so časi utrjevanja olj predolgi za industrijske aplikacije, zato te čase običajno skrajšajo z dodajanjem sikaAvov (Wang et al, 2008). RezultaA časov sušenja za laneno in tungovo olje (preglednica 1) potrjujejo pojasnilo Wanga in Padue (Wang & Padua, 2010). Avtorja sta ugotovila, da se v prvih fazah utrjevanja lanenega olja tvori zaprta plast, ki upočasnjuje difuzijo kisika v spodnje plasA olja in s tem upočasnjuje proces utrjevanja.…”