This report as Part I of the series of the experimental work carried out in the Forintek Eastern Laboratory. Medium density fibreboard (MDF) was produced in the pilot plant with two different treatment of chemical agent at two different dosages. The chemicals were sulphur dioxide (SO2) and sodium bisulphite (NaHSO3). Preliminary test results indicate that:
With the dosage used in the experiment (0.1 – 0.2% of SO2 or 0.16 – 0.8% of NaHSO3 on dry wood fibre), no improvement in dimensional stability (TS and WA) and mechanical properties (IB, MOR and MOE) can be observed.
The results suggest that the dosage used for SO2 or NaHSO3 was higher than required and better result might be achieved with lower dosage as increasing the dosage from lower level to higher level for both SO2 and NaHSO3 reduced the panel strength and dimensional stability.
Based on general observation in the experiment, the runability was good with the introduction of either chemicals. However, SO2 was introduced into the system easier than NaHSO3 without extra process procedures.
The experimental work was verified that it is feasible to inject SO2 into the preheater without the gas leakage or contamination to the atmosphere.
Further experimental work is required to identify the optimal chemical dosage for the treatment and their interaction with different resin systems and wood species.