2.4.3 Thermal characterization

DSC test was carried out using a TA Q2000 differential scanning calorimeter under nitrogen atmosphere at a scanning rate of 10°C/min, with a sample of 10 mg in aluminum pans. The thermal history of the samples was erased by a preliminary heating cycle at 10°C/min from 20 to 200°C and maintaining it at that temperature for 10 min to melting residual crystals, cooling at 10°C/min to 0°C, and finally, they Recycled Polypropylene-Coffee Husk and Coir Coconut Biocomposites: Morphological… DOI: http://dx.doi.org/10.5772/intechopen.81635

were heated at °C/min from 0 to 200°C. The crystallization temperatures (Tc) and melting temperatures (Tm) were determined from cooling and second heating scans. The melting enthalpies values were normalized according to the proportion of the components in the samples. The crystallinity (χc) was determined from the Eq. (13):

$$\mathcal{K} = \left(\frac{\mu\_{H\text{m}}}{\left[\frac{\Delta H\text{m}}{\left(\Delta H\right)\_{m} \* \left(1 - \mu\_{F\text{k}her}\right)}\right]}\right) \* 100\tag{13}$$

where wFiber is the CHF or CCF fiber mass fraction, ΔH is the melting enthalpy of the sample, and ΔH<sup>0</sup> <sup>m</sup> is the specific enthalpy of melting for 100% crystalline PP. This value was reported in literature as 293 J/g [34].

#### 2.4.4 Morphology

Scanning electronic microscopy (SEM) of the biocomposites was carried out on the cryogenic fracture surfaces of the specimens using a Quanta FEG 250 microscope operating at a voltage of 10 kV. The samples were previously sputter coated with gold to increase their electric conductivity. Determinations were performed in different areas of the SEM micrograph.

#### 2.4.5 Statistical analysis

Flexural and impact properties of the materials were subjected to analysis of variance (ANOVA), and the Tukey's test was applied at the 0.05 level of significance. All statistical analyses were performed using Minitab Statistical Software Release 12 (Pennsylvania, United States).

#### 2.5 Environmental characterization of the materials

The environmental characterization of the materials was made through a cradle to gate Life Cycle Assessment based on the ISO 14041 parameters. The only indicator used for this evaluation was the carbon footprint, and the information for the emission factors was taken from secondary information found in literature.
