## 2 Results and Discussion
### Study on the Structure and Properties of Modified Polymer Matrix
Additionally, the end region of the Cole-Cole curve began to warp upward, producing a trailing phenomenon, which signified a new relaxation process in the melt, distinct from that of linear polymers, demonstrating that DVB introduced branched structures into the rPP molecular chain [36]. The trailing phenomenon at the end of the Cole-Cole curve for rPOMD was more pronounced than that for rPMD, indicating that OBC caused DVB to introduce additional branched structures and some cross-linking to the matrix blends, leading to longer relaxation times for the molecular chains. After MAH graft modification alone, the rPM section exhibited numerous small blocky fracture layers and more crack bands than unmodified rPP (Figure 3), indicating typical brittle fracture. The addition of DVB monomer reduced the crack bands left after rPMD fracture compared with rPM (Figure 3c). The morphology of these crack bands resembled viscous tear bands, which favored the ductile fracture of the polymer matrix. Following the addition of OBC, the rPOM fracture surface showed more brittle damage from short-chain PP, with crack bands present. The granular OBC particles and the matrix phase at the fracture surface primarily exhibited a \"sea-island\" structure [33]. The MAH grafting modification enhanced the interface  
Figure 2: Rheological behavior of polymer matrix: (**a**) storage modulus; (**b**) loss damping; (**c**) complex viscosity; (**d**) loss viscosity–storage viscosity curves. compatibility between components, resulting in reduced debonding phenomena (Figure 3d). With the additional incorporation of DVB (Figure 3e), voids left by the debonding of OBC particles at the cross-section were reduced, and granular OBC particles nearly vanished. This suggests that MAH/DVB co-grafting modification enhances interfacial compatibility between PP and OBC. Figure 4a shows that MAH graft modification caused degradation of the macromolecular chain, resulting in a shift in the melt peak of rPM toward lower temperatures. After the addition of OBC and DVB, the melting peaks of rPOM, rPMD, and rPOMD shifted to higher temperatures, though they remained lower than that of rPP. This shift could be attributed to the chain entanglement caused by the branched structures, which restricted the movement of rPP molecular chains at elevated temperatures [35]. However, the short chains generated during the degradation reaction still enhance molecular chain mobility at higher temperatures [36]. The crystallization curves in Figure 4b further showed that the MAH group, branched structure, and heterogeneous nucleation effect of OBC promoted the crystallization of rPP chain segments at higher temperatures. Compared with unmodified rPP, the crystallization temperature (\(T_{\text{c}}\)) of rPM decreased, while the crystallinity (\(X_{\text{c}}\)) increased (Table 1). This was attributed to the difficulty of forming stable nuclei from short chains in rPM at high temperatures,  
Figure 4: DSC curves of the polymer matrix: (**a**) melting; (**b**) crystallization. Figure 3: Fracture morphology of polymer matrix: (**a**) rPP; (**b**) rPM; (**c**) rPMD; (**d**) rPOM; (**e**) rPOMD. nucleation accelerated crystal growth, resulting in increased \(X_{\text{c}}\) for rPM. With the further addition of DVB, melt temperature (\(T_{\text{m}}\)), \(T_{\text{c}}\), and \(X_{\text{c}}\) of rPMD increased and reached their maximum compared with rPM. This could be attributed to the accelerated nucleation and crystal growth rates of rPP chain segments due to MAH and branched structures [36]. In rPP/OBC blends, although the presence of branched structures increased the \(T_{\text{c}}\) of rPOMD compared with rPOM, \(X_{\text{c}}\) still decreased. This decrease could be attributed to improved interfacial compatibility between PP and OBC, as well as chain entanglement between the molecular chains of the two components, which inhibited the movement of rPP chain segments. This inhibition blocked the ordered arrangement of rPP chain segments in the nuclei, reducing the growth rate of crystallite.