Anti-shrinking foaming of polyethylene with CO2 as blowing agent

Low-density polyethylene (LDPE) foams blown with CO2 typically exhibit severe shrinkage problem and poor surface appearance, which makes them have to be prepared by using hydrocarbon as the blowing agent. In this work, we reported a facile method to prepare LDPE foams with good dimensional stability by simply controlling the linear low-density polyethylene (LLDPE) addition and the dissolved CO2 content. The rheological evaluation and foaming behaviors showed that the LDPE/LLDPE blend with a mass ratio of 90/10 possessed better foamability than LDPE and the blends of other mass ratio did. Moreover, the presence of 10 wt% LLDPE in LDPE matrix could not only facilitate the cell nucleation and the formation of open-cell structure, but also effectively solve the shrinkage problem of LDPE/LLDPE foams blown with CO2. The shrinkage behavior was further analyzed by numerical simulation of dimensional stability, and the simulation results agreed well with the experimental results.