2.2.1. Characterization of the Piassava Fiber

The density, length and diameter distributions of the piassava fiber waste m reported in a previous work [39]. The density value of 1.42 g/cm<sup>3</sup> was used to calculate the volume fraction of reinforcement used on each composite in this work.

Initially, 100 fibers were randomly selected from the received batch (after the cleaning process) and had, one by one, their dimensions measured in a profile projector model PJ3150 made by Pantec (São Paulo, Brazil). These fibers were subjected to tensile tests in an Instron model 5582 universal machine with a 2.0 mm/min test speed at a controlled temperature of 20 ◦C. The test was conducted according to ASTM D3822-7 [40]. Adhesive tape was used on both ends of these fibers to avoid slipping as well as any damage that the machine grips may cause during the tensile test.

Images of the fiber surface morphology were obtained by scanning electron microscopy (SEM) on a microscope model SSX 550 made by Shimadzu (kyoto, Japan). Images of the fiber surface morphology were obtained by scanning electron microscopy (SEM) on a microscope model SSX 550 made by Shimadzu (kyoto, Japan).

The density, length and diameter distributions of the piassava fiber waste m reported in a previous work [39]. The density value of 1.42 g/cm3 was used to calculate the volume

Initially, 100 fibers were randomly selected from the received batch (after the cleaning process) and had, one by one, their dimensions measured in a profile projector model PJ3150 made by Pantec (São Paulo, Brazil). These fibers were subjected to tensile tests in an Instron model 5582 universal machine with a 2.0 mm/min test speed at a controlled temperature of 20 °C. The test was conducted according to ASTM D3822-7 [40]. Adhesive tape was used on both ends of these fibers to avoid slipping as well as any damage that

#### 2.2.2. Biocomposites and Resin Processing 2.2.2. Biocomposites and Resin Processing

the machine grips may cause during the tensile test.

2.2.1. Characterization of the Piassava Fiber

*2.2. Methods* 

*Sustainability* **2022**, *14*, x FOR PEER REVIEW 4 of 13

fraction of reinforcement used on each composite in this work.

The biocomposites were made by adding the processed piassava powder in an already mixed component A and B resin, then leaving it at room temperature for 24 h in specific molds for the polymer cure to occur. Figure 1 illustrates the materials used in this study by showing the plain COPU Figure 1a and 30 vol% piassava powder Figure 1b,c biocomposites used for the abrasive wear tests as well as the material applied over a concrete surface. The piassava powder is black and the higher percentage of it added, the darker the biocomposites become. When applied over larger surfaces the material tends to form a smooth and even surface. The biocomposites were made by adding the processed piassava powder in an already mixed component A and B resin, then leaving it at room temperature for 24 h in specific molds for the polymer cure to occur. Figure 1 illustrates the materials used in this study by showing the plain COPU Figure 1a and 30 vol% piassava powder Figure 1b,c biocomposites used for the abrasive wear tests as well as the material applied over a concrete surface. The piassava powder is black and the higher percentage of it added, the darker the biocomposites become. When applied over larger surfaces the material tends to form a smooth and even surface.

**Figure 1.** Plain COPU (**a**) and 30 vol% piassava powder biocomposite (**b**) samples used for abrasive wear tests, and 30 vol% piassava powder biocomposite applied over a concrete surface (**c**). **Figure 1.** Plain COPU (**a**) and 30 vol% piassava powder biocomposite (**b**) samples used for abrasive wear tests, and 30 vol% piassava powder biocomposite applied over a concrete surface (**c**).

Biocomposite specimens were produced inside an open silicone mold. The molds were made according to the dimensions indicated by specific standards [40–42]. The piassava powder used in the preparation of the composites was dried in a stove for 24 h at 60 °C before the biocomposite preparation. To avoid excessive moisture absorption, the piassava powder was mixed with polymer, still heated to the polymer and finally poured inside silicone molds. After the 24 h period of curing, neat COPU, control with 0 vol% of Biocomposite specimens were produced inside an open silicone mold. The molds were made according to the dimensions indicated by specific standards [40–42]. The piassava powder used in the preparation of the composites was dried in a stove for 24 h at 60 ◦C before the biocomposite preparation. To avoid excessive moisture absorption, the piassava powder was mixed with polymer, still heated to the polymer and finally poured inside silicone molds. After the 24 h period of curing, neat COPU, control with 0 vol% of piassava powder, and biocomposites made with 10, 20 and 30 vol% were demolded and the tests were carried out.
