Volatile organic compounds (VOCs) from lauan (Shorea ssp.) plyboard prepared with kraft lignin, soy flour, gluten meal and tannin: emissions during hot pressing and from panels as a function of time

Abstract Soy and corn gluten proteins are common ingredients in adhesives and resins together with kraft lignin and condensed tannin. The relative contribution of these additives to volatile organic compound (VOC) emissions in the course of processing hardwood veneer products was evaluated. Press emissions were captured and separated into condensate and gaseous fractions. High-performance liquid chromatography (HPLC) was employed to characterize aldehydes in condensate and gaseous fractions, while GCMS served for identification and quantitative determination of the compounds in the gas phase. Aldehydes dominate the press emissions with both proteinaceous binders producing significantly higher formaldehyde (FA), acetaldehyde (AcA) and hexaldehyde (hexA) emissions compared to pressed veneer without additives. Other aldehydes, including valeraldehyde and propionaldehyde were also captured, but in relatively lower amounts. In contrast, lignin as a binder led to lower FA content in press emissions, whereas tannin significantly reduced contributions of FA, AcA and other aldehydes. VOC emissions from plywood panels during chamber testing were similar to compounds evolved on hot-pressing.