• Thumm, Armin
• Loxton, Ceri
• Mcdonald, Armando
• Grigsby, Warren

Abstract

Resin binder in composite panels such as medium density fibreboard(MDF)is critical for panel integrity. How this resin is distributed throughout the fibre matrix will have an impact on panel properties. X-ray photon spectroscopy(XPS)has the potential to be used in characterising resin distribution on MDF fibre,as it is a surface analysis technique for determining the composition of elements on the surface of substrates. XPS can be used to calculate the proportion of fibre surface covered by nitrogen containing UF resin to give total coverage of fibre by resin,and may also provide corroborating evidence for resin coverage determined by microscopy methods. XPS was successfully used to determine UF resin surface coverage of fibre in blowline resinated fibre and MDF as well as dry-blended MDF over a range of resin loadings,wax contents and different resin application methods. Comparison of XPS coverage values with those obtained using confocal microscopy(CLSM)coupled with fluorescently labelled resin revealed substantially differing absolute resin coverage of fibre between the two techniques. Although there was a correlation between the two techniques confirming trends in coverage values found by CLSM analysis for dry-blended panels,grouping resin coverage values having more than one processing variation did not establish any relationship between XPS and CLSM coverage values,whether for dry-blended or blowline resinated MDF. Inherent difficulties with this surface-only XPS technique was the high variability of XPS analysis between some MDF samples due to variation in replicate sample surfaces and surface oxidation. Additionally,lower resin coverage was observed on panel surfaces than for unpressed fibre,contrary to CLSM findings. Analysis of panels formed with and without wax suggest wax movement as well as deposition of other materials on the fibre surface during hot pressing lowered surface%N contents,further limiting this technique.

Topics

• Deposition
• density
• impedance spectroscopy
• surface
• x-ray photoelectron spectroscopy
• Nitrogen
• composite
• resin
• hot pressing
• confocal laser scanning microscopy