2.4.1. Content Analysis

Assessing biomass for any conversion or pretreatment process often requires a good understanding of its basic composition and characteristics [1,3,32]. Thus, the major components of the pure and blended pellet samples believed to have greater influence on bonding and pellet quality were considered during the content analysis. Content analysis of both pure and blended samples of NSP and PSP was conducted to determine major organic and elemental components in terms of percentage composition. Details of how these components were quantified are given in Section 2.4.3. However, subsequent analytical instruments were used to investigate and establish di fferences in the mechanism of bonding between the pure and blended pellet samples relevant to bonding and quality of the pellets.

The major organic components of PSP (100%) were quantified by a di fferential scanning calorimeter (DSC), whose make, model, and principle of operation are detailed in Section 2.4.4.

For the major elemental constituents of the pure and blended pellet samples, an energy-dispersive X-ray spectroscope (EDX) connected to a scanning electron microscope (SEM) was used. The analysis (EDX) involved the generation of characteristic X-rays that revealed elements present in the pellet samples. The procedure was such that, the SEM, whose model and mode of operation are detailed in Section 2.4.5, created an image of the samples by scanning them with an electron beam. During this process, an X-ray was emitted from the samples, which was then collected by the EDX instrument after bombardment by an electron beam. The collected X-rays were characteristic of the atomic structure of the elements contained in the pellet samples. Energy level was used to sort the X-rays, after which a plot of X-ray energy versus frequency was obtained. This plot gave an indication of the elements present in the pellet samples and the percentage composition of each element.

The results obtained from this analysis (content analysis) laid the groundwork for data interpretation from subsequent analysis involving the use of other advanced analytical instruments.

### 2.4.2. Fourier-Transform Infrared Spectroscopic Analysis (FT-IR)

Since bonding, from a chemistry perspective, relates to perpetual attraction between atoms, ions, or molecules, there is a need to firstly identify the type of forces acting between individual particles of the pure and blended samples of NSP and PSP prior to identifying chemical alterations caused by blending. However, the goal of this analysis was to determine the influence of chemical alteration on bonding and establish di fferences in the mechanism of bonding between the pure and blended pellet samples relevant to the quality of the pellets. Analysis of this nature would require molecular-level identification of key functional groups with significant impact in bonding. Therefore, FT-IR analysis was invaluable in helping to achieve this goal. The procedure for the FT-IR analysis is briefly described below.

FT-IR measurements of pure and blended samples of NSP and PSP were carried out using a Perkin Elmer FT-IR spectrometer (Spectrum Two). Spectra were scanned at a resolution of 4 cm<sup>−</sup><sup>1</sup> with 32 scans collected in the spectral range of 4 000 cm<sup>−</sup><sup>1</sup> to 500 cm<sup>−</sup>1.
