2.3 Preparation of the biocomposites

r-PP and its biocomposites were compounded in a co-rotating twin screw extruder (Harden Industries Ltd., China). For each case, MAPP, CCF, and CHF fibers were physically premixed with r-PP pellets in a plastic bag using 30% of fibers and 4% of MAPP in weight. A temperature gradient from 140 to 170°C from the feeder zone to the die was used. The rotation speed of the twin-screw was 50 rpm. The outcoming cord of r-PP and its biocomposites from the extruder were pelletized using a mill which produced pellets of about 5 mm long. After the pelletization process, the r-PP and its biocomposites samples were dried in an oven at 85°C followed by an injection molding process. A BOY XS (BOY Machines, Inc., USA) microinjection molding machine was used to prepare samples for flexural and impact tests. Table 5 summarizes the injection-molding processing parameters used. Figure 1 shows the injected specimens of neat PP, r-PP, r-PP-CHF, and r-PP-CCF biocomposites.
