A Novel Type II Photoinitiator with Self-Supplied Hydrogen for Anti-Creep Crosslinking Polyethylene Film.

Two macromolecular photoinitiators, bis(4-benzoylphenyl) malonate (BPMD) and bis(4-benzoylphenyl) 3,3'-(piperazine-1,4-diyl)bis(3-oxopropanoate) (DBPMD), were successfully synthesized from 4-hydroxybenzophenone (4-BP), malonyl chloride, and anhydrous piperazine. Structural characterization using Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy (H NMR) confirmed the expected molecular framework. Ultraviolet (UV) absorption spectroscopy revealed that BPMD and DBPMD exhibited enhanced molar extinction coefficients and red-shifted absorption maxima compared to 4-BP. Migration studies in high-density polyethylene (HDPE) demonstrated significantly lower diffusion rates for BPMD and DBPMD than for 4-BP, with DBPMD exhibiting superior photoinitiation efficiency even in the absence of amine-based activators. Photoinitiation performance, photocrosslinking kinetics, and mechanical evaluations indicated that both BPMD and DBPMD enabled efficient UV-initiated crosslinking, leading to improved tensile strength and creep resistance in polyethylene films. These findings highlight the potential of BPMD and DBPMD as advanced photoinitiators for high-performance UV-crosslinked polyethylene systems.