Desarrollo de un proceso para la obtención de un material compuesto biodegradable reforzado con fibras cortas de carrizo (Phragmites Australis).

Abstract

In the present investigation, a laboratory-scale experimental process is established to obtain a biodegradable composite with short reed fibres as reinforcement. The reed fibre was obtained by steam explosion process with a severity factor of 3.3. The average moisture content of the reed (11.8 %) and the average extraction yield of short fibre (149 - 250 µm) (44.01 %) were determined, which were considered as the basis for the calculation of the process flow diagram (PFD). Using a central composite rotational design with three central points, 11 experimental runs were prepared by varying the weight content of the short reed fibre (FC) and coupling agent (BP-1). The specimens were obtained by injection moulding and their mechanical properties were evaluated under tensile (ASTM D638) and flexural (ASTM D790) stresses. The composite of run 8 (30 %FC, 11.46 %BP-1 and 58.54 %PLA) exhibited the highest tensile strength value of 50.3 MPa, presenting an increase of 11.78 % over the pure PLA value (45 MPa). While, in the flexural test, the composite of run 2 (20 %FC, 10 %BP-1 and 70 %PLA) improved by 11.86 % from 70 MPa (pure PLA) to 78.3 MPa. The experimental investigation shows that the higher the weight content of BP-1 the mechanical properties of the composites show a significant increase, since it allows an efficient transfer of stresses from the matrix to the reinforcement. In order to obtain the biodegradable composite, a PFD was elaborated in AutoCAD and a production of 2.5 kg/h with a composition (30 %FC, 11.46 %BP-1 and 58.54 %PLA) was established. This requires a fresh reed feed of 1.94 kg/h, 0.29 kg/h BP-1, 1.46 kg/h PLA and 0.75 kg/h short reed fibre. And, it is proposed to use a co-rotating twin-screw extruder, which should not exceed a maximum temperature of 170 °C to preserve the structural integrity of the reed fibre.