Wood flour is gaining popularity as an established filler in thermoplastic composites. The intrinsic properties of wood flour combined with resin formulation and type of coupling agent determine the flow properties and the melt processing conditions of the composite for further applications and use. In this work, commercial types of maleated coupling agents with varying molecular weight and MAH graft content were tested to improve the filler-matrix interface adhesion and durability of polypropylene (PP) wood composites. The heat distortion temperature (HDT) has indicated considerable gain in stiffness of the PP filled with wood flour. Thermally aged samples at controlled temperature and times presented gradual increase in stiffness. Further assessment of thermal stability using oxidative induction time (OIT) for different formulations indicated changes in the oxidation mechanism when comparing neat PPs OITs to wood-plastic composites (WPC). Ultraviolet stability was evaluated after weather-o-meter testing in terms of the sample yellowness using DE shifts determined by the Color Test. Power law parameters determined by capillary rheometer have shown no major deviations in flow properties for the wood composites compared to the neat resins. The results assure good moldability conditions for all of the formulations investigated although in some cases melt consistency may be quite sensitive to testing temperature.
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