Water-assited extrusion compounding process to reduce the total Volatile organic compounds in natural fibre-filled composites for automotive interior applications
Résumé
Natural fibre-filled composites are recently considered to be used in interior parts of vehicles because of their eco-friendly and mechanical performance [1-3]. However, they emit VOCs at all stages of their life cycle, such as compounding, injection-moulding and usage [4]. In the present study water-assisted extrusion compounding process has been used to reduce the VOC emission during the usage of injection-moulded parts. Flax and hemp fibres (20 wt.%) reinforced polypropylene composites were compounded in presence of maleic anhydride grafted polypropylene (PP-g-MA) as compatibilizer using twin screw extrusion, with and without water injection during extrusion. Then the compounds where injection-moulded into standard test specimen. Physical and mechanical properties such as morphological, fibre length, tensile and impact properties were characterized as well as the total volatile organic compounds (TVOCs) and odour emission using automotive standard D42 3109-C. Released TVOCs from the composite products were quantified by air sampling on adsorbent followed by thermal desorption and GC-MS analysis. The scanning electron microscopic observation indicated a good dispersion of fibres in the matrix with a low reduction in average length and aspect ratio of fibres. Mechanical properties of samples produced with water-assisted compounding showed slightly reduced modulus and strength compared to the samples prepared without water assistance. For both flax and hemp fibre-reinforced composites, TVOC emissions are reduced by 94% and 30% respectively with water-assisted extrusion. So, the water-assisted extrusion process has proved its effectiveness in reducing VOCs emissions without scarifying the mechanical properties.