Wahyu Dwianto

Characterization of major, unused, and unvalued Indonesian wood species I. Dependencies of mechanical properties in transverse direction on the changes of moisture content and/or temperature

Mechanical property changes due to the moisture content (MC) and/or temperature changes were examined for 15 Indonesian wood species. A static bending test was carried out at 20°C, 65% relative humidity (air-dry), and water-saturated at 20°C (wet-20) and 80°C (wet-80). For individual test conditions, modulus of elasticity (MOE) and modulus of rupture (MOR) increased linearly with specific gravity regardless of wood species; however, maximum deflection did not correlate with specific gravity for any MC or temperature conditions. The relative values of MOE and MOR measured in wet-20 to air-dry conditions were variously affected from slightly to strongly depending on the wood species. However, the relative values always decreased markedly when saturated in water at 80°C, regardless of wood species. The relative MOE, MOR, and maximum deflection values due to the change in MC or MC and temperature combined were independent of specific gravity but may be dependent on wood type: softwood or hardwood.

Quality Improvement of Oil Palm Trunk Properties by Close System Compression Method

ABSTRACT Densification of the inner part of oil palm trunk (OPT) by the close system compression (CSC) method was performed in this study. The effects of the compression temperature and time on the anatomical, physical and mechanical properties of OPT were evaluated. The inner part of OPT with an initial average density of 0.3 g/cm 3 was used as samples. Oven-dried samples were immersed in water and vacuumed until fully saturated andthen compressed by CSC at 120, 140, 160 or 180℃ for 10, 20, 30 or 40 min. The anatomical characteristics of transverse and radial sections before and after compression were compared by optical microscopy. The phys-ical and mechanical properties, including the density, recovery of set (RS), modulus of elasticity (MOE), mod-ulus of rupture (MOR), and compression parallel to grain were examined. It was observed that the anatomical characteristic of the inner part of OPT (i.e., vascular bundles, vessels, and parenchyma tissue) became flattened,fractured, and collapsed after compression by CSC. The RS decreased with increasing compression temperatureand time. The lower RS indicated high dimensional stability. The physical and mechanical properties (i.e., den-sity, MOR, MOE, and compressive strength) of the inner part of OPT increased with increasing compression temperature and time. Compression by the CSC method at 160℃ for 40 min was the optimum treatment. Keywords : close system compression, compressed wood, oil palm trunk, physical and mechanical properties, recovery of set

Water Vapor Sorption Behavior of Arabinoxylan from Corn Pericarp

The influence of the degree of arabinose substitution in arabinoxylan on its water vapor sorption behavior was investigated by comparing the application of the independent dual sorption model and the Hailwood-Horrobin (H-H) model on corn pericarp arabinoxylans with arabinose/xylose ratios of 0.35, 0.26 and 0.12. Characterization of their sigmoid shaped adsorption isotherms grouped in IUPAC Type II indicates the usefulness of the former model to demonstrate the importance of arabinose substituents in increasing the affinity of corn pericarp arabinoxylan for water molecules. The present results open the future applicability of the independent dual sorption model for characterization of the hydration behavior of other branched polymers.

Chemical Properties and Sugar Released of Sengon (Paraserianthes Falcataria (L) Nielsen) Stem and Branchwood

An analysis of wood chemical properties such as extractive alcohol-benzene, lignin, holocellulose and -cellulose of Paraserianthes falcataria (L) Nielsen (Sengon) stem and branchwood have been investigated. This study is also concerned on the sugar released for ethanol production from Sengon branchwood. In this regard, sample of breast-height stem and the first branch of the tree with 10 cm diameter were analyzed by using Mokushitsu Kagaku Jiken Manual standard. The sugar released from enzymatic saccharification of woods was determined using Nelson-Somogyi method. The result showed that the amount of extractive alcohol-benzene, lignin, holocellulose, and -cellulose for Sengon stem were 4.3, 21.1, 77.3, and 52.2 % respectively. While for branchwood, the corresponding values were 3.6, 25.7, 74.7, and 42.1 % respectively. It was also observed that enzymatic saccharification of Sengon branchwood after 48 h released only 9.8 mg of sugar, which was lower than the result of its corresponding stem. The 2nd International Symposium for Sustainable Humanosphere. Hal. 142-145 ISSN 2088-9127

Effect of Phenol Formaldehyde Impregnation on The Physical and Mechanical Properties of Soft-Inner Part of Oil Palm Trunk

The objective of this study was to improve physical and mechanical properties of soft-inner part of oil palm trunk (S-OPT) after impregnation with phenol formaldehyde (PF) resin and densification by close system compression (CSC) method. Effect of different methods of PF resin impregnation (i.e., no vacuum-pressure, vacuum, and vacuum-pressure) was evaluated. The results showed that PF resin impregnation and CSC significantly improved the physical and mechanical properties of S-OPT up to: (1) 176% in density; (2) 309% in modulus of rupture (MOR); (3) 287% modulus of elasticity (MOE); and (4) 191% in the compressive strength. Physical and mechanical properties of S-OPT showed their best performances when PF resin impregnated with vacuum-pressure method as shown by higher weight gain, density, MOR, MOE, compressive strength, and lower recovery of set due to better penetration of PF resin into S-OPT. Combining PF resin impregnation and densification by CSC method could be a good method to improve physical and mechanical properties of S-OPT.