Densification and effect of compression ratio on mechanical properties of CLT from low-density timber

The mechanical properties of CLT manufactured from densified low-density planted timber, Paraserianthes falcataria were studied in relation to changes in the area of pores for under densification. Conditioned laminas (MC ≤ 15%) underwent two-stage densification using hot-press machine at 105oC, 6 MPa, for 10 min each, with press released for 1 min 40 sec in between the stages, before cooling (< 100oC) to reduce immediate springback. The laminas with thickness 8 mm, 10 mm, and 15 mm were produced using metal stoppers and further manufactured into three-layered CLT of 24 mm, 30 mm, and 45 mm thick. 20 mm undensified laminas with 60 mm CLT as the control. Results shows that modulus of elasticity (MOE), modulus of rupture (MOR), and compression parallel to grain have improved significantly and showed negative correlation with area of pores, except for compression perpendicular to grain.

Relationship between cell lumen area and lignin content of alkaline-treated densified timber of Paraserianthes falcataria

In this study, low-density plantation timber, Paraserianthes falcataria was pretreated with 3%, 6% and 9% NaOH before densification process. Alkaline pretreatment leads to lignin reductions and cell wall structure becomes more porous. Densification was done by crushing the cell wall with hot-press machine, resulting in reduction of thickness to about 60%. Scanning electron microscopy images were captured and processed through ImageJ software. As to support the data, lignin content determination was conducted according to TAPPI T222 and the correlation coefficient between cell lumen areas and lignin content were studied statistically.