I. Differences in the Names of Various Types of Plastics (Plastic Pelletizing Machine) (Plastic Granulator)

1. Genuine material: This refers to standard‑compliant, authentic raw materials produced by the factory, which are the primary products circulating in the market through official channels.

2. Runner material: This primarily refers to the leftover portions generated during the injection molding process, which are crushed into recycled granules—also known as scrap or regrind—and may include first‑run runners and second‑run runners.

3. Recycled material: Refers to material that has been recovered and regranulated. It may consist of edge trimmings or waste that has been reprocessed into pellets. In general, it denotes raw material that has already undergone mechanical recycling and regranulation; whether recycled once or multiple times, it is still classified as “recycled material.”

4. Secondary-grade materials: These are distinguished from primary-grade materials in that they fail to meet the required testing standards upon leaving the factory. Compared with primary-grade materials, they fall short on certain performance indicators, but they remain usable in practice.

5. Recycled material: A general term for recycled pelletized resin. It is similar to the term “regrind,” but “recycled material” encompasses a broader range. Recycled materials typically exhibit inconsistent performance across key properties, posing significant risks in use; however, their price is usually only about half that of virgin-grade resin.

II. Identification of Types of Waste Plastics

1. LDPE (Low-Density Polyethylene):

Sensory evaluation: The material feels soft and is white and transparent, though its transparency is moderate; it often contains adhesive tape and printed text. (Note: Adhesive tape and printed text are unavoidable, but their content must be strictly controlled, as they can affect the product’s market price.)

Combustion test: The flame is yellow at the top and blue at the bottom; combustion is smokeless, with a paraffin-like odor; it melts and drips, and readily forms filaments.

2. EVA (Ethylene-Vinyl Acetate):

Sensory identification: The surface is soft, with tensile strength greater than that of LDPE; it feels slightly tacky to the touch (though there is no adhesive on the surface). It is white and transparent, with high clarity, and its appearance and tactile feel closely resemble those of PVC film—care should be taken to distinguish it.

Combustion test: During combustion, it emits a paraffin‑like odor similar to LDPE, with a slight acidic note; the flame is yellow at the top and blue at the base; no smoke is produced; it melts and drips, readily forming filaments. Note: This product is one of several types of polyethylene. Its price is comparable to that of LDPE, it can be used for regranulation, and its quality requirements are identical to those of PE.

3. PP (Polypropylene):

Sensory identification: This product is white and transparent; compared with LDPE, it exhibits higher transparency and produces a crisp sound when rubbed.

Combustion test: During combustion, the flame is yellow at the top and blue at the bottom; the odor resembles petroleum; it melts and drips, with no black smoke produced.

4. PET (polyethylene terephthalate):

Sensory identification: This product is white and transparent, feels relatively hard to the touch, and produces a sound when rubbed. Its appearance resembles that of polypropylene (PP).

Combustion test: During combustion, black smoke is produced, with a flickering flame; after burning, the material’s surface turns black and chars. Rubbing the black charred residue between your fingers yields a powdery substance.

5. PVC film (polyvinyl chloride):

Sensory evaluation: The appearance resembles EVA, but it is elastic.

Combustion test: Produces black smoke when burned, extinguishes immediately upon removal from the flame, and leaves a black residue on the surface with no molten dripping.

At present, China has more than 3,000 waste‑plastic processing enterprises, including nearly 1,600 companies that process and utilize imported waste plastics, with import volumes ranking second worldwide. The market for waste‑plastic utilization is substantial. Moreover, the recycling methods and application areas vary considerably among different types of waste plastics, such as PE, PP, and PET.