# Maleic Anhydride-Grafted Isotactic Polybutene-1 and Modified Polyamide 6
## 3 Results  
### The Grafting Reaction of DVB/MAH onto iPB-1  
The torque behavior of iPB-g-MAH at different DVB concentrations was examined with a torque rheometer (Figure 1a). The reaction torque peaks of graft products appeared with the addition of DVB, and its intensity gradually strengthened when DVB concentration increased. The reason was that the addition of DVB promoted the reaction of MAH with iPB-1 [23]. The end-torque values increased when DVB concentration increased, reflecting the crosslinking trend [24], this trend was consistent with the decrease of MFR in Figure 1b. Figure 2a shows the FTIR spectra of grafted products at different DVB concentrations. Compared with iPB-g-MAH, the sample of iPB-g-MAH-co-DVB had obvious absorption peaks at 1780 cm\({}^{-1}\), corresponding to the carbonyl group (C=O) of MAH [25]. This demonstrated that MAH has been grafted onto iPB-1 successfully. Moreover, the absorption peaks of 711 cm\({}^{-1}\), due to the benzene ring of DVB, indicated that DVB was also grafted onto the macromolecular chains. The peak intensity of grafted products absorption peaks at 1780 cm\({}^{-1}\) increased when DVB concentrations increased, indicating that DVB significantly promoted the Gd of MAH. The Gd in Figure 2b was calculated by the formula (Gd% = 0.3754\(A_{1780\text{cm}^{-1}}/A_{2720\text{cm}^{-1}}\)) and Figure 2a. It can be seen that the Gd and grafting efficiency (Ge) of the grafted products increased when DVB concentrations increased. The reactivity of DVB/iPB-1 macroradicals was higher than that of MAH/iPB-1 macroradicals. Therefore, DVB and iPB-1 macroradicals first converted to styryl macroradicals, then reacted with MAH to grafted products during the grafting reaction. Figure 1: Torque/time spectra (**a**) and MFR (**b**) of isotactic polybutene (iPB)-g-maleic anhydride (MAH) at different divinyl benzene (DVB) concentrations (\(T\) = 180 \({}^{\circ}\)C, dicumyl peroxide(DCP) = 0.6 phr, MAH = 6 phr). Figure 3 shows torque and MFR of iPB-g-MAH at different reaction temperature. The reaction torque peak appeared earlier with increasing of temperature, the reason was that the decomposition of DCP increased. The DCP half-life is 9.2 min at 150 \({}^{\circ}\)C, and only one min at 170 \({}^{\circ}\)C, and the reaction continued due to sufficient free radical concentration. There were two reasons for the reduction of torque: one reason was high temperature which exacerbated the degradation of iPB-1 macromolecules; the other was the viscosity of iPB-1 macromolecules, which decreased when temperature increased. MFR showed in Figure 3b proved that the degradation of iPB-1 macromolecules was the main reason. Figure 4 shows the effect of reaction temperature on Gd and Ge of iPB-g-MAH. The Gd and Ge of iPB-g-MAH increased at 170 \({}^{\circ}\)C. This can be explained by the fact that the decomposition rate of DCP and the reaction rate were matched, and free radical concentration was appropriate at 170 \({}^{\circ}\)C. When the temperature was too high, the decomposition rate of DCP and the transient concentration of free radicals increased rapidly. Meanwhile, the termination rate of free radicals increased, causing the effective concentration of free radicals to decrease, and as a result, the Gd of iPB-g-MAH decreased. Figure 3: Torque/time spectra (**a**) and MFR (**b**) of iPB-g-MAH at different reaction temperature. (DCP = 0.6 phr, MAH = 6 phr, DVB/MAH = 4:6.) Figure 2: FTIR spectra (**a**) and Gd/Ge (**b**) of grafted products at different DVB concentrations. It can be seen from Figure 5a that grafting copolymerization had difficulty proceeding without DCP. The reaction torque peak moved forward, and the torque end values decreased with increasing DCP concentration, indicating that the existence of DCP promoted the degradation of iPB-1 macromolecules. This was confirmed by the apparent increase of MFR in Figure 5b. It can be seen from Figure 6 that DCP as the initiator significantly promoted the grafting copolymerization of MAH.