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Recycled Materials

Millennium Molding uses crumb rubber from recycled tires as it's base stock for molding rubber products. They also make products form recycled plastic and composite material.

Here is how Wikipedia describes the materials they use:

Crumb rubber

is a term usually applied to recycled rubber from automotive and truck scrap tires. During the recycling process steel and fluff is removed leaving tire rubber with a granular consistency. Continued processing with a granulator and/or cracker mill, possibly with the aid of cryogenics, reduces the size of the particles further. The particles are sized and classified based on various criteria including color (black only or black and white). The granulate is sized by passing through a screen, the size based on a dimension (1/4") or mesh (holes per inch : 10, 20, etc.).

Mesh refers to material that has been sized by passing through a screen with a given number of holes per inch. For example, 10 mesh crumb rubber has passed through a screen with 10 holes per inch resulting in rubber granulate that is slightly less than 1/10th of an inch. The exact size will depend on the size of wire used in the screen.

Recycled Plastic Material


Before recycling, plastics are sorted according to their resin identification code, a method of categorization of polymer types, which was developed by the Society of the Plastics Industry in 1988. Polyethylene terephthalate, commonly referred to as PET, for instance, has a resin code of 1. They are also often separated by color. The plastic recyclables are then shredded. These shredded fragments then undergo processes to eliminate impurities like paper labels. This material is melted and often extruded into the form of pellets which are then used to manufacture other products.

Monomer recycling

Many recycling challenges can be resolved by using a more elaborate monomer recycling process, in which a condensation polymer essentially undergoes the inverse of the polymerization reaction used to manufacture it. This yields the same mix of chemicals that formed the original polymer, which can be purified and used to synthesize new polymer chains of the same type. Du Pont opened a pilot plant of this type in Cape Fear, North Carolina, USA, to recycle PET by a process of methanolysis, but it closed the plant due to economic pressures.[2]

Thermal depolymerization

Another process involves the conversion of assorted polymers into petroleum by a much less precise thermal depolymerization process. Such a process would be able to accept almost any polymer or mix of polymers, including thermoset materials such as vulcanized rubber tires and the biopolymers in feathers and other agricultural waste. Like natural petroleum, the chemicals produced can be made into fuels as well as polymers. A pilot plant of this type exists in Carthage, Missouri, USA, using turkey waste as input material. Gasification is a similar process, but is not technically recycling since polymers are not likely to become the result.

Heat compression

Yet another process that is gaining ground with startup companies (especially in Australia, United States and Japan) is heat compression.[citation needed] The heat compression process takes all unsorted, cleaned plastic in all forms, from soft plastic bags to hard industrial waste, and mixes the load in tumblers (large rotating drums resembling giant clothes dryers). The most obvious benefit to this method is the fact that all plastic is recyclable, not just matching forms. However, criticism rises from the energy costs of rotating the drums, and heating the post-melt pipes.

Other processes

A process has also been developed in which many kinds of plastic can be used as a carbon source in the recycling of scrap steel.[3]