Effect of Sodium Hydroxide, Succinic Acid and Their Combination on Densified Wood Properties

Abstract

The effect of NaOH, succinic acid and their combination used as pretreatments on selected properties of densified wood samples of pisang putih (Mezzettia spp.), nyatoh (Palaquium spp.) and sepetir (Sindora spp.) has been studied. The properties of these samples were then compared with those of untreated wood (control) and densified wood samples without any pretreatment (HD wood). For alkali-pretreatment, after immersion in 10% NaOH (w/w) for 1, 2 and 3 h, the samples were immediately compressed; for acid-pretreatment, the sample was impregnated with 10% succinic acid (w/w) using a vacuum of −50 kPa for 30 min and a pressure of 7 bar for 2 h before pressing; while for the combination-pretreatment, the sample was initially immersed in 10% NaOH then impregnated with 10% succinic acid (w/w) and finally densified/compressed. Compression was applied in a radial direction and carried out in an open system using a hot press machine at 180 °C and 7 MPa specific pressure for 30 min with a 40% compression ratio. The results showed that densified wood with or without pretreatment had a higher specific gravity (SG) than the control, whereas sepetir wood showed the greatest increase in SG. The alkali- and combination-pretreatments resulted in a higher C-set value than in the control, HD and acid-pretreated samples. Acid-pretreatment resulted in the best improvement in dimensional stability compared to the other pretreatments. Increasing the immersion time in NaOH solution was proven to be able to increase dimensional stability both in alkali- and combination-pretreatments, although water absorption values varied.

Dimensional Stability and Mechanical Properties of Citric Acid Impregnated Samama Wood (Anthocephalus macrophyllus (Roxb) Havil) at High Curing Temperatures

“…is in accordance withAugustina et al (2023c),Feng et al (2014),Laksono et al (2023), andLee et al (2020).…”

Wood impregnation in relation to its mechanisms and properties enhancement

“…Hardwood and softwood have been impregnated with a variety of impregnating agents such as waxes and oils (Lesar and Humar 2011;Esteves et al 2014;Ahmed et al 2017;Belchinskaya et al 2021), thermosetting resins, including epoxy, phenol formaldehyde, urea formaldehyde, etc. (Furuno et al 2004;Gabrielli et al 2010;Zhao et al 2016;Biziks et al 2018;Schwarzkopf et al 2020;Wang and Zhao 2022), monomer/polymer, including methacrylate, acrylate, styrene, unsaturated polyester, followed by radiation or catalyst-thermal treatment (Chao et al 2003;Hadi et al 2013), noncyclic and cyclic anhydride (Li et al 2001;He et al 2020;Augustina et al 2021), as well as organic acid (Fang et al 2000;L'Hostis et al 2017;Grosse et al 2019;Lee et al 2020;Augustina et al 2022). These types of impregnating agents have been classified as either nonbonded-leachable (NBL), nonbonded-nonleachable (NBNL), or bondednonleachable (BNL), depending on the bonding efficiency of the impregnating agent to and from the wood cells (Rowell and Young 1981).…”