Interfacial characterisation of flax fibre-thermoplastic polymer composites by the pull-out test

The interface between flax fibres and thermoplastic polymer matrices has be en investigated. Two types of flax fibres have been used: dew retted and up graded Duralin fibres. The latter fibres have been treated by a novel treat ment process for improved moisture and rot sensitivity. The apparent shear strength of dew-retted and upgraded Duralin fibres embedded in high and low density polyethylene, polypropylene and maleic anhydride modified polyprop ylene, respectively, been calculated from the maximum force measured from t he pull-out test using the Kelly-Tyson equation. Higher apparent shear stre ngth values have been measured in the case of high density polyethylene. An improvement in the interfacial shear strength by the use of upgraded flax fibres has not been clearly observed. The curves of pull-out force versus d isplacement for all samples are typical of a brittle fracture mixed mode in terface behaviour. The pull-out test of flax fibre-polymer matrices exhibit similar characteristics with the pull-out test of synthetic fibre-polymer systems.