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Volume 73 (2022), issue 1

Long-Term Hygroscopic Thickness Swelling Rate of Hydrothermally Treated Beech Wood / Polypropylene Composites

Research subject and fields:

Long-term hygroscopic thickness swelling rate of polypropylene (PP) composites filled with thermally treated wood flour was investigated. The beech wood chips were heat treated at 120 °C, 150 °C or 180 °C for 30 or 120 min using saturated steam in a digester. The composites based on PP, beech wood flour (BF), and coupling agents (PP-g-MA) were made by melt compounding and injection molding. The weight ratio of BF to PP was controlled at 50/47 for all blends. The amount of coupling agent was fixed at 3 wt.% for all formulations. Further study was conducted to model thickness swelling of the composites, a swelling rate parameter (KSR). The thickness swelling of thermally-treated samples at 120 ºC for 30 min and at 150 ºC for 30 min were lower than that of control samples, followed by thermally-treated samples at 180 ºC for 120 min, at 180 ºC for 30 min, at 120 ºC for 120 min, and at 150 ºC for 120 min, respectively. Furthermore, the thickness swelling of the BF/PP composites decreased with increasing time and temperature of the thermal-treatment. In addition, at 120 ºC for 30 min, the composites showed a lower swelling rate than control samples. The KSR of the composites was influenced both by the time and temperature of thermal treatment.


Faculty of Forestry and Wood Technology

DRVNA INDUSTRIJA Scientific Journal of Wood Technology

ISSN 0012-6772 (Print) / ISSN 1847-1153 (Online)

Faculty of Forestry and Wood Technology University of Zagreb, Svetošimunska 25, 10000 Zagreb, Hrvatska - Croatia
Tel: +3851 2352 430, E-mail:
Editor-in-Chief: Prof. Ružica Beljo-Lučić, Ph.D. E-mail: