*3.1. Visual Aspect*

The appearance of the injected specimens of TPS and TPS/ASP after the different reprocessing cycles are gathered in Figure 2a,b, respectively. Table 6 summarizes the color indexes (L\*, a\* and b\*), and the color variation measured by ∆*E* ∗ *ab*, with respect to TPS and TPS/ASP biocomposite with only the first processing cycle (TPS-1 and TPS/ASP-1, respectively).

**Figure 2.** Visual aspect of the injected specimens subjected to different reprocessing cycles. (**a**) Starch thermoplastic polymer (TPS) (**b**) TPS/ASP biocomposite.

The reprocessing cycles had more effect on the change in color of TPS/ASP biocomposite than in the unfilled TPS. As expected, the L ∗ value decreased (white to black) in both cases. a\* and b\* coordinates changed progressively after each reprocessing cycle. Moreover, after the second processing cycle, the obtained ∆*E* ∗ *ab* value of TPS was 1.00 (TPS-2). After the third reprocessing cycle, the value slightly increased to 1.91 (TPS-3); only an experienced observer could notice the difference in color [13]. However, in the case of TPS/ASP, after the second processing cycle, the value obtained of ∆*E* ∗ *ab* was 3.96 (TPS/ASP-2), which resulted in samples whose change in color could be noticed by an observer (3.5 < ∆*E* ∗ *ab* < 5). The color variation clearly showed an increasing tendency in

reprocessing, as expected due to degradation [13]. The ∆*E* ∗ *ab* was more remarkable and noticeable for TPS/ASP biocomposite.


**Table 6.** Color parameters (*L* ∗ , *a* ∗ , *b* ∗ and ∆*E* ∗ *ab* injection-molded samples of starch thermoplastic polymer (TPS) and TPS/ASP biocomposite subjected to different reprocessing cycles.
