Supplementary fibre supplies for the manufacture of MDF and particleboard. Part VIII. Effect of different types and substitution levels on non-wood fibre sources on the properties of MDF panels
Experimental work was carried out to investigate the effect of replacing different types of non-wood fibre sources in MDF panels and the effect of their substitution levels on the mechanical and physical properties of the panels. Three types of non-wood fibre sources, switch grass, reed canary grass and corn stalks, were studied with different substitution levels, in normally and commonly used refining and hot pressing processes. The conclusions are made based on the results of the experiment:
In general, the non-wood fibres studied in this experiment, namely, switch grass, reed canary grass, and corn stalk, have lower acidity as compared to wood expressed by higher value of pH and acid buffer capacity. It suggests that the resin system needs to be adjusted for the effective use of these lower acidity raw materials if UF or MUF resin being used.
In terms of the internal bond (IB) strength of the panel, replacing wood fibre with non-wood fibre generally did not affect the panel IB as the substitution level was low. There was no detrimental effect to the IB when adding 12.5% of switch grass content. At the 50% of non-wood fibre substitution level, IB strength was almost the same for the panels made with 100% wood, 50/50 wood/reed canary grass, 50/50 wood/corn stalks, and 50/50 wood/non-wood fibres (consisting in equal amounts of switch grass, reed canary grass and corn stalks). The experiment proved that non-wood fibre can be a viable fibre source for the manufacture of MDF.
There was no detrimental impact on the panel thickness swelling (TS) and water absorption (WA) when replacing wood with non-wood fibres. However, under the process condition used in the experiment, both TS and WA were higher than normally expected even for the control panels using 100% wood.
There was no obvious difference in panel MOR and MOE when replacing the wood with non-wood fibres.
In comparison of different types of non-wood fibres studied in the experiment, they generally performed similarly in terms of panel mechanical and physical properties.