Thermomechanical (TMP) and chemo-thermomechanical pulps (CTMP) for medium density fibreboards (MDF)

Thermomechanical (TMP) and chemo-thermomechanical pulps (CTMP) were prepared from spruce under different pulping conditions. The fibres were dried at 70°C and medium density fibreboards (MDF) were made therefrom in pilot plant scale using urea-formaldehyde resins as a binder. The results of testing the physical-mechanical properties reveal that the pulping temperature has a significant influence on the thickness swelling and water absorption of the boards. MDF prepared from fibres produced at high pulping temperature (180°C) generally show lower thickness swelling and water absorption than MDF made from fibres produced at low pulping temperature (140°C and 160°C). However, high pulping temperature may have a negative effect on the internal bond strength of the boards. In general, CTMP leads to MDF with higher internal bonding strength compared to those derived from TMP. In addition, the influence of different drying conditions (150°C and 170°C) of TMP and CTMP on the physical-mechanical properties of MDF was assessed. MDF made from CTMP showed lower thickness swelling when dried under high temperature.