FUNCTIONALIZED HIGH-DENSITY POLYETHYLENE WITH BLOCKED ISOCYANATE GROUP

Blocked HI (BHI) was synthesized by the reaction of HI (2-hydroxyethyl methacrylate combined with isophorone diisocyanate) with ϵ-caprolactam (CPL). CPL was used as a blocking agent to improve storage stability of HI. From the Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance ( 1 H-NMR) spectra it was found that NH group in CPL reacted with remaining isocyanate (NCO) groups in HI at 80°C for 8 hours. Grafting of BHI onto HDPE was carried out in a xylene solution using a radical initiator. By the FT-IR spectra, we confirmed the introduction of BHI onto HDPE and measured the relative extent of grafting. Deblocking temperature of BHI grafted onto HDPE was determined by monitoring the regeneration of isocyanate group at 2270 cm −1 with FT-IR spectra. Differential scanning calorimetry (DSC) analysis was used to determine the thermal properties of HDPE and BHI functionalized HDPE. DSC results showed that there was no crosslinking reaction during the grafting reaction of BHI onto HDPE. Processability of functionalized HDPE was evaluated by its dynamic rheological behaviors. When the functional group (BHI) was introduced onto HDPE, tensile strength of BHI functionalized HDPE showed higher value than that of HDPE, while elongation at breaks vice versa.