Fiber Pretreatment and Its Effects on Wood Fiber Reinforced Polypropylene Composites

ABSTRACT

This study investigates the effect of pretreatment of fiber with NaOH and coupling with maleated polypropylene (MAPP) on the physical and mechanical properties of composites, based on radiata pine (Pinus Radiata) fiber, produced with a polypropylene matrix, using a twin-screw extruder followed by injection molding. Prior to reinforcement, the fiber was treated with NaOH. The effect of treatment was assessed using zeta potential, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Tensile testing, SEM, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were carried out to assess the effect of modification on composite properties. An increase of 106% for strength and 302% for Young's modulus were obtained by using 60 wt% fiber and 2 wt% MAPP, compared to the unreinforced matrix. Fiber pretreatment with NaOH reduced strength but improved Young's modulus (370% compared to unreinforced matrix) of resulted composite.

Keywords:

• Alkali treatment
• Composite
• Coupling agent
• Environmentally friendly
• Extrusion
• Injection molding
• Interfacial bonding
• Lignin
• Maleated polypropylene
• Polypropylene
• Scanning electron micrographs
• Thermogravimatric analysis
• Thermoplastic matrix
• Wood fiber
• X-ray diffraction
• Zeta potential

ACKNOWLEDGEMENTS

The authors would like to thank Foundation for Science Research and Technology, New Zealand, for their financial support of this project.