# Thermal and Thermomechanical Characterization of Polypropylene-Seed Shell Particles Composites
## 3 Results
### DMA Results  
Figure 5 shows the DMA thermograms of the storage modulus and tan \(\delta\) with respect to the temperature of the PP and PP-JA composites. In Figure 5a, it can be observed that the addition of JA causes a decrease in the value of the storage modulus when the JA content increases, being that PP-8-JA is the composite that presented a lower value of storage modulus. This behavior is due to the fact that the presence of JA generates an agglomeration effect in the vitreous region, as was reported previously with high particle concentration (50%wt) [26]. The results obtained are contrary to other works that report an increase in the storage modulus with the addition of pistachio particles in polyolefins [4], attributing this behavior to a better adhesion between the PI and the polymeric matrix. Figure 5b shows the behavior of tan \(\delta\) with respect to temperature. This signal allows for the identifying of the relaxations experienced by a polymer with respect to temperature, and the magnitude of the tan \(\delta\) peak establishes the behavior of the polymer in terms of temperature, its ability to flow or deform elastically, so that the width and height of the peak can be associated with the damping ratio of the material. It can be seen that the ratio of tan \(\delta\) for the composites is higher compared to that of the pristine PP; in addition to the fact that its width increases, this behavior is typical when the materials have a greater capacity to dissipate energy, that is, they have a greater tendency to flow than to deform, which is also associated with more complex structures. This behavior was previously reported [34], and attributed to the presence of rigid lignocellulosic fillers that can replace  
Figure 4: TGA thermogram of % weight loss (**a**) and derivative of %wt(°C), (**b**) for PP, PI, and PP-PI composites. the amorphous regions of the matrix, which is reflected in the variation in the tan \(\delta\) ratio. On the other hand, two relaxations can be observed both in the pristine PP and in the PP-JA composites; the first at an approximate temperature of 10 \({}^{\circ}\)C, which is associated with the glass transition of the PP, which is observed not to present a change significant in its value as the concentration of JA increases, and the second relaxation at a temperature close to 80 \({}^{\circ}\)C, which is attributed to a laminar and rotational slip mechanism in the crystalline phase of the polymer. These results differ from previous works, which found that the addition of particles of lignocellulosic materials produces an increase in Tg, since the presence of the particles prevents the movement of the polymer chains [4; 35]. On the other hand, Figure 6a shows the DMA thermograms of storage modulus against temperature for PP and PP-PI composites, where it can be seen that the PP-8-PI composite was the one that presented a lower storage modulus, compared to the rest of the composites, which had modulus values very close to the pristine PP. This behavior is opposite to that previously reported by our working group, with the difference of the properties of PP, which has a higher melt flow value, in addition to the fact that the pistachio particles underwent a chemical treatment with NaOH solution [25]. Figure 5: DMA thermogram for PP and PP-JA composites. (**a**) Storage modulus versus temperature, and (**b**)tan \(\delta\) versus temperature. Figure 6 shows the DMA thermograms of the storage modulus and tan \(\delta\), with respect to temperature for pristine PP and PP-PI composites; a similar behavior is observed for PP-PI composites, which show a similar modulus value to pristine PP, except for the PP-8-PI composite, which shows a significant decrease in the temperature range of the analysis. On the other hand, in Figure 6b it is observed that the tan \(\delta\) curve shows a behavior similar to that shown by the PP-JA composites; however, in this case, the peak is much wider and a dissolution in the Tg of the compounds is identified.