Abstract

Particleboard manufacture

Since the current research was focused on the comparison between binderless particleboard and conventional particleboards using urea-formaldehyde (UF) or melamine-formaldehyde (MF) adhesive, this research was conducted by using three wood species as raw materials. The three wood species from a community forest, namely, sengon (Paraserianthes falcataria), gmelina (Gmelina arborea), and mindi (Melia azedarach), were purchased from a wood material supplier. Particle sizes were 10 to 20 mesh, and binderless particleboards were made according to the method of Suhasman et al. (2011). The oxidation process of sengon wood was done with 5 percent hydrogen peroxide based on ovendry particle weight (wt/wt) and 5 percent ferrous sulfate based on hydrogen peroxide weight (wt/wt); the other two wood species were oxidized with 15 percent hydrogen peroxide (wt/wt) and 7.5 percent ferrous sulfate (wt/wt). The different amount of hydrogen peroxide and ferrous sulfate for gmelina and mindi woods compared with sengon wood were referred to in our previous study (Suhasman et al. 2011). In this study, the best physical and mechanical properties for binderless particleboard made from gmelina and mindi woods were found in the boards produced using 15 percent hydrogen peroxide and 7.5 percent ferrous sulfate, while the best characteristic for sengon binderless particleboard was found in the board produced using 5 percent hydrogen peroxide and 5 percent ferrous sulfate. The boards were hot pressed at 180°C for 12 minutes and 25 kg/cm² pressure and then conditioned at room temperature for 8 months. The moisture content of the boards prior to test was 7 to 10 percent determined by the ovendrying method.

For the purpose of comparison, UF and MF resins were used to manufacture particleboards with a resin level of 10 percent based on the ovendry weight of wood particles. The boards were hot pressed at 120°C for 7 minutes with the same pressure and conditioning period as the binderless particleboards. Board size was 30 by 30 by 0.7 cm (length by width by thickness), and 0.75 g/cm³ was the density target.

Subterranean termite test

For the subterranean laboratory test, the termites were collected from the arboretum of the Forestry Faculty at Bogor Agricultural University in Indonesia. Collected termites were placed in a dark room in the laboratory with litter and wood for acclimatization for a month. Five 2 by 2 by 0.7-cm particleboard specimens were placed in 450- to 500-mL wide-mouth round glass jars with a bottom area of 25 to 30 cm². Two hundred grams of moist sand (7% moisture content under water holding capacity) and 200 healthy and active worker subterranean termites (C. curvignathus) were added to each glass jar, and the glass jars were placed in a dark room at 25°C to 30°C at more than 70 percent relative humidity for 4 weeks. To maintain the humidity, glass jars were weighed every 3 days and water was added if moisture loss was more than 2 percent. At the end of the test, particleboard weight loss percentage based on ovendry weight was determined (SNI 2006b). Fewer than 10 percent of the termites were still alive at the end of the test.

Field test

Eight 10 by 2 by 0.7-cm particleboard specimens were placed between two pieces of 2-cm-thick plywood with 1-cm stickers on both sides. The boards were placed horizontally on the ground and covered with dark cloth in the field (arboretum of Bogor Agricultural University Campus) for 6 weeks (Fig. 1). The test was carried out in September and October 2011. The degree of attack was monitored using sample control for 1, 2, 3, 4, 5, and 6 weeks of exposure. In the sixth week, sample control was heavily attacked. At the end of the test, the degree of failure of the particleboard was determined according to Pablo and Garcia (1997), as shown in Table 1. Each sample was visually observed, and the sample condition was determined.

View Figure

• Download as Powerpoint
• Download Figure

Table 1. Particleboard failure degree.

View Fullscreen

Dry wood termite test

Dry wood termites were taken from the laboratory collection. A glass tube (3 cm in height by 1.8 cm in diameter) was placed on the center of five 5 by 2 by 0.7-cm particleboard specimens, and 50 worker dry wood termites (C. cynocephalus) were introduced into the glass tube. The samples were then put in a dark room for 12 weeks, and wood weight loss percentage was determined at the end of the test (SNI 2006b). Fewer than 10 percent of termites were alive at the end of the test for gmelina and mindi woods, and for sengon wood, fewer than 15 percent of the termites were still alive at the end of the test.

Data analysis

A 3 × 3 factorial in a completely randomized design was used to analyze the data. The first factor was wood species, namely, sengon, gmelina, or mindi, and the second factor was the type of particleboard, namely, binderless, UF, or MF. Duncan's test was used for further analysis if the factor was significantly different.

Subterranean termite test

Weight loss percentage in laboratory tests and degree of failure of particleboard specimens in field tests are shown in Tables 2 and 3, respectively. The analysis of variance is shown in Table 4, and Duncan's test for further analysis is shown in Table 5. The data in these tables show that wood species significantly affected the weight loss percentage of particleboard specimens in laboratory tests, and the further tests in Table 2 show that sengon particleboard had the greatest value, 8.7 percent, compared with other particleboards, 5.2 and 6.0 percent for gmelina and mindi, respectively. The last two particleboards were not significantly different from each other. Sengon wood had the largest amount of weight loss because its density was the lowest, resulting in it being more susceptible to termite damage. A similar result was suggested by Hadi et al. (2010), who stated that mindi wood was more resistant than sugi wood because of the difference in its density. Furthermore, particleboard type and interaction of particleboard type and wood species did not affect weight loss of the board, which indicated that binderless particleboard resistance to subterranean termite attack did not differ significantly from that of conventional particleboard made with UF and MF resins.

Table 2. Board weight loss percentage by subterranean termite attack in laboratory tests.

View Fullscreen

Table 3. Board failure degree by subterranean termite attack in field tests.

View Fullscreen

Table 4. Analysis of variance results.^a

View Fullscreen

Table 5. Duncan's test for further analysis.^a

View Fullscreen

For field tests, both wood species and particleboard type affected failure degree of the particleboards, and interaction of both factors did not significantly affect this result. Sengon particleboard had the highest value with an average score of 97, followed by gmelina and mindi (with average scores of 84 and 43, respectively). These values were apparently affected by the wood density of the raw material for the particleboard. Based on their analysis of six hardwood species, Arango et al. (2006) suggested a significant inverse association between percentage of mass lost with termite attack and the specific gravity of the wood; in other words, wood with a higher specific gravity has more resistance to Reticulitermes flavipes Kollar termites. With regard to the particleboard type, binderless particleboard had the largest value with the average score of 86, and this value was different from conventional particleboards, namely, UF and MF particleboards, with average values of 70 and 68, respectively. The conventional particleboards were not different from each other, and it was suggested that formaldehyde played a role in making particleboard more resistant to termite attack. In both the laboratory and field tests, sengon and binderless particleboards were more susceptible to attack by the subterranean termite.

Dry wood termite test

Weight loss percentage of particleboard in the dry wood termite test is shown in Table 6, and the analysis of variance is shown in Table 4. From these data, it is apparent that wood species, particleboard type, and interaction of these factors did not significantly affect weight loss of particleboard. Sengon and binderless particleboards had the highest values compared with the other wood species and particleboard types, respectively, which was similar to the subterranean termite test.

Table 6. Weight loss percentage in the dry wood termite test.

View Fullscreen