Evaluation of potassium humate material in wood-plastic composite production

Aim of study: The aim of the study was to investigate the usability of potassium humate material as an additive to improve some properties of wood-plastic composites. Area of study: The fire retardancy and mechanic properties of the wood-plastic composites. Material and Methods: The medium-density fiberboard (MDF) powder and high-density polyethylene (HDPE) granule mixture was pelletized by using a parallel twin-screw extruder. The obtained composite pellets were molded into boards via hot pressing method. Some mechanical, physical, thermal and fire properties of the produced boards were investigated. Moreover, the chemical properties of the composites were analyzed by using Fourier Transform Infrared (FTIR) spectroscopy. Main results: The results showed that the addition of potassium humate increased the tensile and flexural strengths by 15% and 9%, respectively. However, the water uptake and volumetric swelling of the composite samples increased from 1.15% up to 2.52% and from 3.2% to 5.77%, respectively. LOI and linear burning rate tests indicated that the potassium humate addition increased the fire resistance of composite samples by 3% O2 (LOI) while it improved the burning rate as being 6.62 mm/min lower. Research highlights: The addition of the potassium humate into the wood-plastic composites enhanced the fire, thermal and mechanical properties of the material to some extent