Abstract

The landfills store a lot of waste plastics, thus it has been confirmed a main source for the occurrence of plastics/
microplastic. Although there are some reports that microplastics (MPs) can generate in leachate and refuse
samples from the landfill, it exist many blanks for the evolution of physical and chemical characteristics of waste
plastics and microplastics with different landfill age. To explore the process that large pieces of plastic are
fractured into microplastics, the waste plastics with landfill age from 7 to 30 years are surveyed from a typical
landfill in Shanghai. The results show that PE and PP are the most common types of landfilling plastics, and their
chemical composition also have changed due to the creation of C––O and –OH. Moreover, the crystallinity is
affected by plastic type and landfill age. The crystallinity of PP increased from 24.9% to 56.8%, but for PE, the
crystallinity decreased from 55.6% to 20.8%. The mechanical properties of waste plastics were reduced significantly,
which may be caused by changes in carbon-chain molecules. Al, Ti, Co, and other metal elements were
detected on the plastic surface. The hydrophobic behavior of waste plastic is constantly decreasing
(102.2◦–80.1◦) under long-term landfilling. By investigating the changes in the physical and chemical characteristics
of waste plastics with different landfill age can shed light upon the process of environmental weathering
of waste plastics. This provide theoretical guidance for reducing the transport of microplastics to the
environment.