where Nb = N -1 is the number of bonds in the DB backbone. The vector inner products (𝑛 ⃑ 𝑖 • 𝑛 ⃑ 𝑖+𝑠 ) are averaged over all backbone configurations. This function describes the decay of orientational correlation along the backbone between bond vectors separated by s number of bonds. As shown in Figure , G(s) increases with grafting density, suggesting that the backbone rigidity is enhanced with an increasing number of sidechains. The increase in G(s) with graft density suggests that the backbone rigidity is reinforced by the repulsive sidechains. Consequently, linear polymers have more room to achieve a stretched configuration and experience a corresponding rise in stress compared to polymers with a high graft density. To experimentally test the simulation results, we compared two polymers one linear and one branched and pressed films to mimic the fusing process. The weld strength of Engage 8402 (branched) and HDPE (linear) films shown in Figure demonstrate qualitatively similar behavior with our CGMD simulations. Engage 8402, a branched PE formed by copolymerization with octene, achieved complete fusion after welding for 60 s, as the maximum stress during lap shear tests stabilized at approximately 0.33 MPa. Additionally, in two of the three specimens welded for 60 s and all specimens welded for 80 s, the interfaces became isotropic to the bulk and withstood the lap shear tests without rupture. In contrast, HDPE samples showed a continuous increase in maximum stress, reaching 0.6 MPa as welding time extended from 40 s to 160 s. Notably, two of the three samples welded for 160 s ruptured outside the overlap area, further indicating that the interfaces had become isotropic to the bulk. Despite being heated under a 1000 kg load to enhance interfacial diffusion, the ungrafted linear HDPE required a longer welding time than the branched Engage 8402 to achieve complete interfacial fusion. This trend agrees well with our CGMD simulations. Given the chemical similarity between octene and ethylene oligomers, we can confidently attribute the observed transition in mechanical performance to the effects of side chains. Furthermore, unlike Engage 8402, HDPE exhibited brittle behavior, with interfacial stresses significantly lower than its saturated properties. It is important to note that HDPE has a larger crystalline phase than Engage 8402, which can contribute to the differences in mechanical properties. However, we believe that the crystalline phase alone cannot fully explain the slower saturation of HDPE's interfacial strength. If the enhancement of HDPE's interfacial strength were determined by its crystalline phase, no variation would be observed among HDPE samples, as they were subjected to identical cooling conditions.