Protection of a low-density mangrove timber species gewa (Excoecaria agallocha) through preparation of particleboard – An Assessment
A A Mahfuz, M O Hannan, M A Islam, M N Islam , M M Islam, A K Lahiry
It is now well established that the conversion of low-density and low-cost timbers into laminated, composite and densified form is an alternative of wood protection by means of wood preservatives. Once only the timber species gewa (Excoecaria agallocha) was used for manufacturing newsprint paper in Bangladesh, which is not continued today. The feasibility of commercial production of particleboard from gewa as an alternate raw material was evaluated for its physical and mechanical properties as compared with those of mixed wood particleboard i.e. mixture of pitali (Trewia nudiflora), kadam (Anthocephalus chinensis) and chatian (Alstonia scholaris). It was found that density of gewa particleboard is 628 kg/m3 and mixed wood particleboard is 617.87 kg/m3. The MOR of gewa particleboard is 158.4 kg/cm2 and mixed wood particleboard 204.2 is kg/cm2. The MOE of gewa particleboard is 18611.1 kg/cm2 and mixed wood particleboard is 26,020.5 kg/cm2. The screw holding capacity at edge was higher in gewa than mixed wood (98.2 kg Vs 89.1 kg) and also at face it is higher in gewa than mixed wood (117.3 kg Vs 72.4 kg). The moisture content after curing was lower in gewa particleboard than that of presently used wood particleboard (7.37% Vs 8.20%). Swelling percentage was lower in gewa particleboard than mixed wood particleboard after both 2 and 24 hours soaking in all directions. The similar trend was also found for water absorption after 2 and 24 hours. The assessment revealed that the particleboard of gewa is superior to those of existing mixed wood species. Hence the gewa is an alternative species for indirect protection of other rarely available timbers used for particleboard in Bangladesh.