Evidence of structural order recovery in LDPE based copolymers prepared by gamma irradiation

• LDPE based copolymers for catalytic processes were prepared by γ irradiation.
• Materials structural stability was evaluated based on its crystallinity evolution.
• Grafting degree and radiation dose of preparation were fundamental parameters.
• DSC and FTIR analysis were used for materials characterization.
• Partial structural order recovery was observed in high grafted films.

PE-g-HEMA films prepared by the mutual gamma irradiation method were prepared to be used as catalyst support in catalytic membrane reactors (CMR). These copolymeric films showed good structural stability, even the high grafted ones, with a consistent correlation between their grafting degree and crystallinity. However, it was observed that above a certain radiation dose threshold, the structural changes induced in polyethylene (PE) backbone do not depend only on the extend of poly(HEMA) graft but also in what seems to be the reorganization of the amorphous regions in the PE matrix. The recovery of some crystallinity (up to 8%) in the copolymeric films was attested by DSC data. FTIR analysis confirmed this observation, revealing a slight increase in intensity and definition of the characteristic peak indicator of high crystalline regions in PE. This process seems to result from a radiation protective effect on copolymers matrix carried out by grafted poly(HEMA) which give to PE the ability to recover some of the lost structural order.