No abstract

Many wood processing industries use short rotation teak, which has lower quality especially in durability and dimensional stability. Heat treatment is an eco-friendly method to improve dimensional stability and durability of wood. The objectives of the study were to investigate the effects of thermal modification on chemical composition, colour, dimensional stability and durability as well as coating's performance after accelerated weathering of short and long rotation teak for exterior utilization. In this study, the samples were heated in oven at 220 °C for 20 h under nitrogen atmosphere. Results showed that independently of growth conditions teak woods underwent hemicelluloses degradation and an increase of lignin content after heat treatment. Extractives contents were lower in short rotation than in long rotation teak, and decreased in all cases after heat treatments. Dimensional stability was considerably improved as indicated by anti-swelling efficiency values of 64,9% and 58,9% for short and long rotation teak, respectively. Heated teak woods were more resistant against Trametes versicolor and the durability of short-rotation teak increased from moderate to very durable. Coatings on heat treated teaks had better bonding quality and better photo-stability when compared to unheated. Heated short rotation teak could be considered for exterior application.

Sengon, jabon, and acacia are fast-growing tropical wood species that are important for several wood industries in Indonesia. The purpose of this research was to evaluate the surface roughness and wettability of some heat-treated, fast-growing Indonesian wood species. Surface roughness was evaluated using the mean arithmetic deviation of the profile (Ra), whereas wettability was determined by measuring the contact angle method. The wood was subjected to heat treatment at 120, 150, or 180°C for 2 or 6 h using a small kiln unit. The heat treatment modification reduced the moisture content, wood density, and surface roughness and increased the wettability properties of all wood species. Jabon wood was the smoothest, followed by acacia and sengon, whereas jabon had the lowest wettability, followed by acacia and sengon. Wood anatomy has influences on those properties tested. Heat treatment did not affect surface quality but revealed a significant difference in wettability properties.

European beech (Fagus sylvatica L.) is a major tree species of European forest which is underexploited because of its low dimensional stability and durability. Similarly to what has been developed with radiata pine, furfurylation might be the answer to optimize the utilization of local beech wood. Beech wood furfurylation process was studied using five different catalysts: maleic anhydride, maleic acid, citric acid, itaconic acid, and tartaric acid. Optimization of the furfurylation process was investigated for different catalyst and furfuryl alcohol (FA) contents, and different duration of polymerization. The following properties were studied: weight percent gain (WPG), leachability, anti-swelling efficiency (ASE), wettability, modulus of elasticity, modulus of rupture, Brinell hardness, and decay durability. Tartaric acid, never investigated up to now, was retained as catalyst to perform furfurylation due to its efficacy compared to other catalysts and its novelty. Wood modification with FA and tartaric acid as catalyst led to samples with high WPG even after leaching, improved ASE, and lower wettability with water. Increasing the polymerization duration increased the fixation of FA in treated wood. Most of all, treatment gave a significant improvement in mechanical properties and resistance to wood decaying fungi.

In the near future, wood demand will be fulfilled by local fast growing woods from community forest. Among those, samama (Anthocephalus macrophyllus) is an endemic wood in Celebes and Moluccas. This species has been cultivated throughout Indonesia and usually harvested at age of less than 10 years. This research was conducted to examine the quality of samama wood at 8 and 10 years old. Each age group was represented by three healthy trees. Samples were made from 1 cm segmentation from pith to bark. Modified exponential curve was used to determine the transition of juvenile and mature wood in which maturity limit was achieved when growth parameter had reached the asymptote line. The quality parameters were specific gravity, moisture content, fiber length, fiber wall thickness and microfibril angle. The result showed that the first 6-8 segmentations from the pith were still juvenile, while the subsequent segments were mature wood. The 8 years old had 33.3-38.9 % of juvenile portion, while it was only 30.4-34.8 % in the 10 years old. This finding will be important in considering a proper technology for samama wood processing.

Teak is a famous commercial timber; however, many community forests produce low-quality teak from young trees. This research aimed to investigate the effect of heat treatment on the dimensional stability and colour of young teak wood. Wood samples were pre-dried using a fan or in an oven at 40°C. The heat treatments were conducted at three temperatures (120, 150, and 180°C) and for two durations (2 and 6 h). Water absorption, dimensional stability, and colour tests were then performed. The results showed that the density of the teak wood slightly decreased after heat treatment. However, its dimensional stability improved substantially, in accordance with its reduced water absorption. Furthermore, the surface of the young teak became darker, with a more even brown colour.

The suitability of bamboo’s basic characteristics is very important for more specific purposes, such as composite raw materials. Anatomical, physical, mechanical, and chemical characteristics are some of bamboo’s fundamental characteristics. This study analyses the basic properties, such as physical, mechanical, and chemical properties of bamboo from the Forest Area with Special Purpose (FASP) Pondok Buluh Sumatera Island, Indonesia (I); analyses the relationship between the properties of each type of bamboo (II); and chooses the type of bamboo with the best properties that have the potential to be applied to composite materials, such as laminated bamboo (III). This study used materials consisting of six species of bamboo from the FASP Pondok Buluh. The manufacture of physical and mechanical test samples refers to the ISO 22157 standard, 2004, while the chemical properties test refers to the TAPPI 1999 standard. The chemical, physical, and mechanical properties of bamboo vary widely among species. The lowest holocellulose and α-cellulose content were found in the Kuning Bamboo (B. vulgaris var. vittata). The content of holocellulose and α-cellulose causes the lowest density in Kuning Bamboo (B. vulgaris var. vittata). The Dasar Bamboo (Bambusa vulgaris) has the highest levels of lignin. The substances have an impact on moisture content, T/R ratio, and shear strength. The Dasar Bamboo (Bambusa vulgaris) has the lowest moisture content, the highest T/R ratio, and the highest shear strength. However, Betung Bamboo (Dendrocalamus asper) has the highest density in this study. The compressive strength of the Betung Bamboo (Dendrocalamus asper) has the highest value. Therefore, Betung bamboo and Dasar Bamboo in this study were potentially utilized for composite materials, such as laminated bamboo.

A common problem with fast-growing hardwoods is dimensional instability that limits use of their wood. In this study, we investigated the effects of pre-drying methods, temperatures, and heating duration on the specific gravity, water absorption, and dimensional stability of three tropical fast-growing hardwoods, jabon (Neolamarckia cadamba Roxb.), sengon (Falcataria moluccana Miq.), and mangium (Acacia mangium Willd.). Wood samples were pre-dried by two methods (fan and oven at 40 °C), and heat treatments were performed at three temperatures (120, 150, and 180 °C) for two different time periods (2 and 6 hours). The specific gravity, water absorption, dimensional stability, and structural changes of the samples were evaluated. The results revealed that heat treatments slightly reduced the specific gravity of all three wood species. In addition, the heat treatments reduced water absorption and significantly improved dimensional stability of the samples. Oven pre-drying followed by heat treatment at 180 °C for 6 hours resulted in good physical improvement of jabon and sengon wood. Fan pre-drying followed by heat treatment at 180 °C for 2 hours improved the physical properties of mangium wood. The heat treatment shows a promising technique for improving the physical characteristic of fast growing hardwoods.