performance requirements of recycled polystyrene
performance requirements of recycled polystyrene plastic
In accordance with the standard of Recycled Polystyrene GB/T 4006.1-2021, Section 5.6:
| NO. | ITEM | UNIT | MFR≤30 | MFR>30 |
| 1 | ash content(600士25C) | % | 1≤ | 3≤ |
| 2 | Moisture content | % | 1≤ | 1≤ |
| 3 | Density | % | 1.30≤ | 1.30≤ |
| 4 | Coefficient of variation (MFR) | % | 20≤ | 20≤ |
| 5 | Tensile strength | MPa | ≥18 | ≥18 |
| 6 | Vicat softening temp | °C | ≥80 | ≥80 |
| 7 | Residual styrene monomer content | mg/kg | ≤500 | ≤500 |
All recycled polystyrene particles that meet the above performance indices are qualified products.
However, it is not applicable to the manufacturing of XPS/EPS boards.
The recommended indices are as follows:
| NO. | ITEM | UNIT | MFR≤30 | MFR>30 |
| 1 | ash content(600士25C) | % | 0.2≤ | 0.2≤ |
| 2 | Moisture content | % | 0.5≤ | 0.5≤ |
| 3 | Density | % | 1.1≤ | 1.1≤ |
| 4 | Coefficient of variation (MFR) | % | 15≤ | 15≤ |
| 5 | Tensile strength | MPa | ≥30 | ≥30 |
| 6 | Vicat softening temp | °C | ≥80 | ≥80 |
| 7 | Residual styrene monomer content | mg/kg | ≤500 | ≤500 |
1. Ash content significantly affects the density and cell size of XPS boards. The higher the ash content, the finer and denser the cells of the XPS board, which in turn affects the expandability (expansion rate) of polystyrene.
The density of the manufactured XPS boards is extremely high, which significantly increases production costs. When the ash content exceeds 0.5%, foaming may not be possible, and it is only suitable for injection molding processes, not extrusion processes.
2. Coefficient of variation (MFR): Exceeding the standard for the coefficient of variation (MFR) will increase the difficulty of XPS manufacturing and require frequent adjustments to the equipment's process parameters.
This leads to waste of raw materials. The performance of the produced XPS boards is inconsistent (compression index, shrinkage index, thermal conductivity index).
It is prone to form local contraction or present a phenomenon where the compressive index in the middle of the XPS board is high while it is low on both sides.
3. Moisture content: Excessive moisture content reduces the foaming and expansion performance of recycled polystyrene, and at the same time, it can cause the finished XPS board to shrink and deform.
Drying treatment can be adopted to reduce moisture.
4.Suitable for the production of XPS boards: MFR 5-15
(Different types of polystyrene can be fully mixed to achieve raw material MFR of 5-15)
