Influence of interphase properties on the effective behaviour of a starch-hemp composite
Résumé
Elasticity behaviour of a fully biopolymer composite is studied using both numerical and experimentalapproaches. Hemp fibre-starch composite is thermomoulded using a varied content of hemp fibres. Onone end, mechanical testing reveals loss of stiffness due to limited load transfer with the increase of fibrecontent. On the other end, two-phase theories predict a reinforcement trend due to contrast of phaseproperties. In order to meet both ends, a numerical study is performed to study sensitivity of the pre-dicted mechanical response to geometrical and mechanical considerations. Filler content, arrangementand interphase properties are some of the major studied effects. Interphases are accounted numericallyto exhibit the mismatch of load transfer due to imperfect interface behaviour. Finite element results arediscussed based on geometrical and mechanical considerations using a sensitivity analysis. Identificationof interphase parameters for the tested experimental conditions is attempted successfully. The three-phase model is able to detect where the two-phase system approximation is valid. In addition, stronginterphase properties are identified despite the apparent loss of stiffness. Such loss turns to be relatedto fibre clustering, which makes thermomoulding processing not suitable to achieve fibre volume con-tents above 10% if not combined with an energetic mixing stage.