Study on aging mechanism of waste polystyrene in landfill
This study simulated the photo-thermal aging of discarded polystyrene(PS)in a landfill environment.Firstly,the molecular structure of the aged samples was characterized.The aging process of PS was then studied through X-ray diffraction,differential scanning calorimeter tests,and the tool-narayanaswamy-moynihan(TNM)model,along with molecular dynamics calculations of enthalpy relaxation processes.The results indicated that PS undergoes chain scission after photoaging,with the molecular weight decreasing from 112 200 to around 13 000.This process generates PS oligo-mers,benzoic anhydride,acetophenone,and methyl benzoate.Furthermore,aging leads to a reduction in PS crystallini-ty and the glass transition temperature.The enthalpy relaxation changes rapidly in the early stages of aging,gradually slowing down as aging progresses,with a corresponding enthalpy value of 4.2 J/g at equilibrium.
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