Document Type : Research Paper

Authors

• Asghar Taremian
• Mahdi Shahverdi ¹
• Saeid Eshaghi ²
• Hadi Dashti ²

¹ MSc. Student, Department of Wood and Paper Science & Technology, Faculty of Natural Resources, University of Tehran; Young Researchers Club, Islamic Azad University, Karaj Branch

² MSc. Student, Department of Wood and Paper Science & Technology, Faculty of Natural Resources, University of Tehran

Abstract

In this study, the susceptibility of poplar (P. nigra) tension and normal wood to collapse during drying was investigated. Thus, the poplar boards with nominal dimensions of 100 × 50 × 25 mm (L×T×R) were dried using three different drying schedules. In schedule A, the boards were dried under constant conditions (dry-bulb temperature of 60⁰C and wet-bulb temperature of 44⁰C); in schedules B and C, they were dried under a time-based schedule, consisting of 4 and 2 steps, respectively. The initial dry-bulb temperature in schedules A, B and C were selected as 60, 60 and 82⁰C, respectively. After drying, the severity of collapse in the cross section of boards was determined by scanning electron microscope (SEM). The results revealed that collapse did not occur in the boards dried by schedule A. Collapse occurred slightly in the boards dried by schedule B and severe collapse and cell wall degradation developed in the boards dried by schedule C. In the latter, gelatinous layer of tension wood was separated from fiber cell walls. Tension wood was more sensitive to collapse than normal wood. Based on the results, it can be concluded that the occurrence of collapse is influenced by initial dry-bulb temperature rather than wet-bulb depression.  

Keywords

• Poplar
• collapse
• drying
• drying schedule

Main Subjects

• Biology and Wood Protection