Appearance method:
Appearance identification is mainly through vision, touch, smell and so on to observe the appearance characteristics of plastic products, such as the shape, transparency, color, luster, hardness and so on.
Plastic after recycling and reprocessing process, color, luster, strength and so on will change, no return color will generally be more transparent, mixed with return products will reduce transparency; the luster of the return material is poor; experienced old injection molding personnel can use tooth bite to initially determine the strength of the plastic, with the addition of the return material is more brittle. The external method is generally used as a preliminary identification of plastic returns.
Physical performance test method:
The density of different kinds of plastics is usually quite different, and the density difference of the same kind of plastics before and after recycling will also be quite different.
The density method can be used to identify the plastic return, but it can not be used to judge the plastic return completely, because there will be many voids or other defects in the process of plastic recovery and reproduction. For example, the regeneration process of ABS/PC produces a lot of small pores, and the number of holes increases with the increase of regeneration times.
For impact strength, tensile strength, compression strength, bending strength and other strength properties, with the increase of plastic content, there will be a significant decrease trend, especially the tensile strength and bending strength will decrease obviously.
The decrease of these strength properties is closely related to the formation of voids and the decrease of defect and molecular weight in the process of recycling. Therefore, for the identification of plastic return, these strength properties of plastics can be tested, and whether the product contains backfill can be preliminarily determined by comparison.
Dissolution method:
Different plastics can be identified by the solubility of plastics in different organic solvents, and plastic returns can also be identified. Because it is difficult to achieve high purity in the process of recycling and reuse, there will be some impurities, resulting in the solubility of the reclaimed materials is not as good as that of raw materials, and there will be residues in the process of organic solvent dissolution.
The commonly used plastic dissolved organic solvents are benzene, xylene, tetrahydrofuran, ether, acetone and formic acid. However, the dissolution method has great limitations, many plastic products will be added a variety of fillers in the process of processing, which affects the comparison between the return material and the original material.
Therefore, there is a great error in the identification of material return by dissolution method, but it is a faster method to identify the type of plastic return material.
