Bending Strength of Lignocellulosic Materials in Softening Condition

Abstract

BENDING STRENGTH OF LIGNOCELLULOSIC MATERIALS IN SOFTENING CONDITION.Manually rattan and bamboo are more easily bent than wood. A further question, whether these are due to the softening behaviour of chemical components or their anatomical structures. This research is aiming to understand the softening behaviour and viscoelastic property of wood, rattan and bamboo as lignocellulosic materials. Nine years-old fast-growing teak wood (Tectona grandis L.f.), rattan (Calamus sp.), and three-yearsold andong bamboo (Gigantochloa pseudoarundinaceae (Steud.) Widjaja) were used for the experiments. Wood and rattan samples were taken from the bottom, middle and upper parts. Bamboo samples were cut from the 1 st to 20 th internodes. Static bending tests were carried out in fresh (green) as control samples, air-dried, and softened by microwave heating (MW) for 1 minute to determine the modulus of rupture (MOR) and modulus of elasticity (MOE). The results showed that the MOR and MOE values of wood, rattan, and bamboo increased from fresh to air-dried condition, and decreased by MW. When compared at the same density, a drastic increase was observed for the normalized MOR value in air-dried rattan, i.e. 2.5 fold. However, the decreasing of all the normalized MOR values were almost the same, i.e. 0.5 fold when MW softened them. The improvement also appeared for the normalized MOE value in air-dried rattan, i.e. 3 fold and decreased to almost zero by MW. These results indicated that rattan was more easily bent, followed by bamboo and then wood. Hydrothermal properties of chemical components significantly affected the changes of strength (MOR) and elastic properties (MOE). However, the differences in bending strength of wood, rattan, and bamboo were more likely due to differences in their anatomical structures.

Variations in the Vascular Bundle and Fiber Structure during the Stem Development of Rattan (Calamus caesius Blume)

“…The infrared absorption intensity at the middle position was the highest. Xylan was the main component of hemicellulose, and the chemical composition and proportion of each hemicellulose depended on the plant species and developmental stage [65][66][67]. Affected by HCA, the unimodal imaging at 1733 cm −1 could not strictly reflect the variation of hemicellulose at different positions.…”

Fixation Process of Laminated Bamboo Compression From Curved Cross-Section Slats

“…On the other hand, the density of bamboo increases from the bottom to the upper parts of the stem and from the inner to the outer parts (Rosalita, Nugroho, Subiyanto, & Kusumah, 2009;Yu, Jiang, Hse, & Shupe, 2008). Dwianto et al (2020) reported the density of 3 years old Andong bamboo (Gigantochloa pseudoarundinacea (Steud.) Widjaja), which was taken from the 1 st to 20 th internodes, increased from 0.48 g/cm 3 at the bottom to 0.74 g/cm 3 at the upper parts.…”

“…The strength characteristics also have the same pattern because the strength of a material is greatly influenced by its density (Dwianto et al, 2020). Therefore, an effort should be conducted to uniform the density by using densification technique.…”