For recycling plastics, thermal, chemical, and material recycle are now applying. The ideal approach of plastic recycle would be to use material recycling, which is reusing without incurring chemical changes, and to employ thermal recycling only for materials that are difficult to reuse, or when material recycling is impractical. However, the ratio of material recycle is still remained low ratio for in these 10 years.<br/>The reasons is mainly the physical properties of products made from recycled plastics are inferior to those made from virgin plastics.<br/>In this time, we investigated mold condition dependence of waste plastics and found their mechanical properties depend much on molding conditions. This can be considered the crystal strucuture was modified by the shear deformations in the molding process and this cause the physical degradation of waste plastics. However,this physical degradation can regenerate by selecting physical treatment (figure shows the concept).<br/>We also found tha even chemically degraded, mix of other plastics, or contain much contaminants, waste plastics changed to show very good mechanical property by choosing a molding condition. The reason is that the origin of low mechanical properties of recycled plastics is physical degradation in the process of molding. Physical degradation is not irreversible and by choosing suitable physical molding process, we can regenerate mechanical properties of recycle plastics.

Relationship between poor physical property of recycled polymer and its molded history

251st National Meeting (2016)

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