Polypropylene-natural fibre composites. Analysis of fibre structure modification during compounding and its influence

TERENZI, ANDREA; PUGLIA, DEBORA; BARBOSA, SILVIA ELENA; KENNY, JOSÉ M.

Composite Interfaces

Springer

Año: 2008 vol. 15 p. 111 - 129

0927-6440

The final properties of the composite materials are greatly related to the residual geometrical parameters (length, diameter, and aspect ratio), orientation and distribution of the fibres in the matrix, which are in turn related to the processing conditions. In this study, fibre structure variation during the processing of a polypropylene matrix reinforced with cellulose flax pulp for different reinforcement concentrations is analysed. The fibre’s geometrical parameters, length, diameter and aspect ratio have been measured and their statistical distributions have been assessed for each concentration. Furthermore, the effect of the microstructure variation on the final mechanical properties is analysed. In particular, changes in the interfacial area were evaluated based on the hypothesis that the fibres were cylindrical in shape and considering the average values of the diameters and the lengths calculated using a statistical distribution approach. The fibre interfacial area after the process decreases as the fibre concentration increases and this evaluation explains how the adhesion methods that are used for fibre surface modification fail because of the decrement in the modifier interfacial density. Halpin Tsai approach was used to model the experimental data obtained from tensile tests for different suspensions, so as to confirm the effect of fibre parameters, such as aspect ratio and interfacial area values, in the PP/cellulose blends final properties.