Uses of polypropylene recycled particles

Polypropylene recycled particles are everywhere in life, and plastic waste can be recycled and reused to make particles that can be used in all aspects of life. However, the application areas are different. For example, convenience bags made of recycled particles cannot be used for food packaging, and some particles processed from PVC may contain toxins themselves, so their application scope is limited. Generally speaking, the first and second grade materials can be used for film blowing, wire drawing, etc., while the third grade materials can generally only be used for injection molding.

What are the classifications of recycled particles

Polyethylene PE

Polyethylene PE is colored into milky white translucent, waxy, the product feels slippery when touched by hand, flexible and tough; slightly stretchable. Generally, low-density polyethylene has better transparency and is softer. High density is harder.

Polypropylene PP

Polypropylene PP is white translucent when colored, waxy, lighter than polyethylene; transparency is also better than polyethylene. Harder than polyethylene

Polystyrene PS

When the polystyrene PS is colored, the transparent product falls on the ground or has a metal-like crisp sound when it is hit; good gloss and transparency

polyvinyl chloride PVC

Polyvinyl chloride PVC is yellow, translucent and shiny.

The easiest way to distinguish from appearance is to distinguish by color. The new material PP is transparent milky white, most of the recycled PP is dark silver or gray. The reason is that the recycled PP is produced by crushing, washing, drying, and compressing PP SCRAP of various colors, so it will not produce transparent milky white .

Secondly, the appearance of the new material PP is round, and there are no bubbles or no bubbles in the particles. Recycled PP has a rectangular cross-section with right-angled particles and bubbles inside.

The reason is the difference in the production methods of recycled PP and new material PP. The new material PP is made to comply with the Under Water Cutting method in which the compressed PP is taken out of the water and directly cut (Cutting) in mass production. Recycled PP is produced by cutting compressed PP in water after cooling. As the new material PP is cut in water before cooling and then cooled, the particles aggregate together to form a round shape, while the recycled PP is cut into a rectangular shape after cooling. In addition, during the production of recycled PP, when it is cooled in water, scrap contains a lot of water when it melts in the compressor, so the particles will have many bubbles. When the new material pp cools in the water, the particles shrink and generate bubbles, but at this time, the bubbles generate uniform shapes inside the particles, and there are many cases that are invisible to the naked eye.

When the difference in appearance is difficult, the physical properties will be different.

The density of new material PP is 0.90 (g/cm3) uniform, and the recycled PP is composed of scrap so the density will exceed 0.90 (g/cm3).

There is a difference in bending strength. The bending strength of new material PP is about 1,600 ~ 1,700 Mpa, while recycled PP is lower than it. (The same product is 980 ~ 1,050 MPa)

The taste of the pellets is different. Recycled PP has peculiar smell in many cases, while new material PP is almost odorless or faint candle smell.

And if the particles are burned, the new material PP will have smoke and the smell of candle burning will completely burn, and the recycled PP will have smoke or residue after burning.