Effects of succinic acid impregnation on physical properties of sapwood and heartwood from plantation-grown short-rotation teak

The aim of this study was to improve the properties of 15-year-old short rotation teak wood using a succinic acid (SA) treatment without excessively increasing the weight gain. The samples were classified as sapwood (SW) and heartwood (HW). Samples were immersed in 10 concentration SA solutions (w/w), followed by vacuuming at -50 kPa for 30 minutes, and applying 7 M Pa of pressure for 2 hours. They were then analysed for specific gravity (SGs), dimensional stability, including tangential/radial ratio (T/R Ratio) and water absorption (WA), weight percent gain (WPG), chemical uptake (CU) and void volume filled (WF). Our results showed that SGs increased in treated SW and HW by 2.33 and 1.23, respectively, as compared to the untreated wood (0.60 and 0.66). The increase in SGs was the result of SA penetration into wood cell walls. The WPG and CU values increased slightly to 5.54 and 0.87 g cm−3 for SW and 3.46 and 0.62 g cm−3 for HW, respectively. The greater increase of SGs in treated SW is due to a greater ease of treatability in SW than HW. The T/R ratio of treated HW decreased by 29.34 from the initial T/R ratio, whereas SW remained unchanged. The WA of treated SW and HW decreased by 42.67 and 55.46, respectively compared to untreated wood. Treated wood performed better on dimensional stability, especially in terms of T/R ratio and WA values for HW. Our results show that the impregnation of short rotation teak wood with SA provides a significant increase on dimensional stability with a negligible increase in weight gain.