Effect of Fiber Length on Curing and Mechanical Behavior of Pineapple Leaf Fiber (PALF) Reinforced Natural Rubber Composites

The introduction of natural fibers as a filler into rubber matrix can be of relevance for their eco-friendly nature and sustainability. In particular, it is expected that natural fibers would assist the stiffening of rubber, which would in turn depend on the geometry, in particular on the aspect ratio (length/diameter) of fibers introduced. Here, short untreated pineapple leaf fibers (PALF) were introduced with random orientation into a natural rubber (NR) matrix. Different lengths (5, 10, and 15 mm) and various amounts (ca. 12, 21, and 35 wt.%) of untreated pineapple fibers are used as the filler for natural rubber composites. The composite was fabricated using vulcanization at 150 degrees C after mill roll mixing. Several properties have been determined, namely curing time, tensile and tear characteristics, and hardness. The results indicated a clear transition between rubbery and hard plastic behavior and also that curing is still feasible, though slower, even with the highest amount of fibers of the maximum length used. An improved tear, further increasing with the amount of fibers, and generally higher hardness has also been obtained.