Quantification of polypropylene (PP) in wood plastic composites (WPCs) by analytical pyrolysis (Py) and differential scanning calorimetry (DSC)

The common use of wood together with traditional chemical polymers opens new possibilities in the field of sustainable product development. Wood plastic composites (WPCs) are an ideal combination of these raw materials, which can be produced with standard plastic technology such as extrusion or injection moulding. Wood to plastic ratio in a WPC influences quality and price, thus adaptation of analytical tools for material testing and quality assurance is required. In this study, the suitability of analytical pyrolysis (Py) and differential scanning calorimetry (DSC) was investigated to quantify the amount of polypropylene (PP) in WPCs. The reliability of these methods was tested by analysing WPCs with different ratios of wood and PP. The amount of PP can be determined with DSC based on its melting point as the influence of wood is negligible in this context. The increment of typical PP markers and decrement of wood markers was observed and quantified in the pyrograms if the PP content in WPCs was elevated. Thus, the ratio of PP and wood can be reliably quantified by means of online and offline analytical pyrolysis.