Peningkatan mutu beberapa lesser-used wood species melalui teknik impregnasi dan kompregnasi

Abstract

Efforts to improve the properties of the three lesser-used wood species, namely nyatoh (Palaquium spp.), sepetir (Sindora spp.), pisang putih (Mezzettia spp.) from natural rain forests in North Kalimantan Province, especially wood strength (represented by specific gravity/SG), dimensional stability and durability have been carried out in order to improve their quality and added value. The techniques used are impregnation and compregnation. Impregnation was carried out by vacuum-pressure (‒98 kPa 15 minutes and 350 kPa for 4 hours) using five types of impregnants, namely PEG (representing nonbonded-leachable), conventional phenol formaldehyde (PFK), low molecular weight PF (LmwPF) and sodium silicate (SS) (representing nonbonded-nonleachable), as well as succinic anhydride (SA) (representing bonded-nonleachable), followed by hot immersion in each impregnant solutions (80 °C) for 3 hours. Compregnation was carried out using a hot press machine (160 °C) and a specific pressure of 2,672 MPa for 15 minutes with a compression ratio (CR) of 20 and 40% from the initial thickness. All parameter measurements were carried out according to applicable standards. Apart from being compared among treatments, the results were also compared to untreated wood. The results showed that the two techniques applied could improve the properties of wood compared to untreated wood. In general, compregnation technique results in a higher improvement than impregnation. Percentage of improvement varies according to wood species and type of impregnating agents. The SG, dimensional stability and durability of impregnated and compregnated woods of nyatoh and sepetir increased significantly, but not for pisang putih wood. Compared to other impregnating agents, SA is the best. The SG and dimensional stability of SA-impregnated wood are significantly improved, while the durability is comparable to that of untreated wood. The best improvement in wood durability was obtained in the treatment using LmwPF. Result also showed that the concentration of impregnant solution also significantly contributes to that improvement. Impregnated wood with 11% LmwPF is belonged to the durable class I. Immersion in hot impregnant solution, as a pretreatment, can reduce the leachability and spring back phenomenon. In general, the characteristics of compregnated wood with SA are better than those of compregnated wood with LmwPF.