## 2 Results and Discussion  
### Study on the Structure and Properties of Modified Polymer Matrix  
After melt grafting modification, new absorption peaks at 1787 cm\({}^{-1}\) appeared for rPP (Figure 1a). These peaks corresponded to the carbonyl groups of cyclic anhydrides and the carboxylic acid formed after hydrolysis of the anhydride, indicating successful grafting of MAH onto the rPP molecular chain [34]. After the addition of DVB and OBC during MAH grafting, the carbonyl absorption peaks showed an increase at 1725 cm\({}^{-1}\) (Figure 1b). This suggested that more MAH monomers were grafted onto the modified matrix. The increased MAH grafting rate aligned with the rise in carbonyl absorption intensity in the infrared spectra, confirming successful grafting of MAH onto the matrix molecular chain. After MAH/DVB co-grafting modification, rPP/OBC blends showed a higher MAH grafting rate than rPOM. (Figure 1c). The melt mass flow rate (MFI) of rPM increased compared with that of unmodified rPP (Figure 1d). This increase was attributed to the severe chain scission of rPP macromolecular chains caused by the initiator, which reduced the flow resistance of the rPM melt. The addition of DVB monomer and elastomer OBC inhibited rPP chain degradation, resulting in lower MFI values for rPMD and rPOM, although these values remained higher than those of rPP. Meanwhile, the MAH grafting rate increased. This suggests that the highly reactive DVB introduced branching in the matrix molecular chains, promoting MAH grafting [33; 35]. Additionally, the polyolefin segments in the OBC chains facilitated MAH grafting and induced limited branching of macromolecular chains. Compared with unmodified rPM, the storage modulus (G\({}^{\prime}\)) of rPOM and rPMD melts gradually increased in the low-frequency region, with a reduced slope at the curve's end, more prominently in rPMD (Figure 2a). This increase was attributed to DVB-induced chain extension, which introduced branched structures into the rPP molecular chains [36]. Moreover, the additional incorporation of OBC promoted DVB-induced branching, enhancing chain entanglement and reducing the melt's viscous deformation. In the low-frequency region, DVB addition reduced the tan\(\delta\) of rPMD compared with rPM, making it lower than that of unmodified rPP. (Figure 2b). This suggests that DVB altered the topology of the rPP molecular chains, resulting in the formation of branched structures [35]. The branched structure with a strong chain entanglement effect prolonged the alpha relaxation of the rPP chain ends and gradually increased the elastic portion of the melt in the low-frequency region [37]. Following the additional incorporation of OBC, the tan\(\delta\) of rPOMD in the low-frequency region was lower than that of rPMD. This suggested that OBC increased  
Figure 1: FTIR spectra (**a,b**), MAH grafting degree (**c**), and melt flow rate (**d**) of the modified rPP. molecular chain entanglement in the melt, further enhancing the melt's elastic response. As shown in Figure 2c, the chain scission process reduced the complex viscosity (\(\eta\)*) of rPM compared with that of unmodified rPP, which displayed distinct Newtonian fluid properties in the low-frequency region. The addition of DVB and OBC effectively inhibited the chain scission of rPP molecular chains, resulting in increased \(\eta\)* for rPMD and rPOMD. The presence of branched structures increased resistance to molecular chain flow orientation, enhancing melt shear thinning and exhibiting typical non-Newtonian fluid properties. The straight-line portion of rPM in the Cole-Cole curve is shorter than that of unmodified rPP, attributed to the faster onset of short-chain relaxation (Figure 2d). The addition of DVB and OBC increased the lengths of the straight-line portions of rPMD and rPOMD in the Cole-Cole curve compared with rPM. This indicated that enhanced chain entanglement prolonged the relaxation time of the melt's molecular chains.