Pvc

' (polyvinyl chloride)

FIGURE 1.5 Coding of thermoplastics.

Some common end uses for recycled HDPE are plastic pipes, lumber, flowerpots, trashcans, or nonfood application bottles. Some end uses for recycled LDPE are plastic trash bags and grocery sacks, plastic tubing, agricultural film, and plastic lumber.

There are mainly three stages needed to recycle plastics. The initial stage, where the wastes are collected, sorted, separated, and cleaned, is labor intensive, requiring little capital investment and relatively no technical skills. Automating this stage requires high capital and might not be economically visible to be able to continue with recycling. Careful attention of this process is very important to guarantee the economics of recycling. It is always recommended to use plastic coding system shown in Figure 1.5 to sort plastic easily and to enhance the properties of recycled plastic. The second-stage, preprocessing, is where the collected wastes are being prepared for processing. In this stage, the wastes are reduced in size by undergoing cutting, shredding, and agglomeration. The final stage is the processing stage, where mixing, extrusion, blowing, injection, and product manufacturing takes place. All types of thermo plastics can be recycled if they are sorted and properly cleaned, as shown in Figure 1.6.8

FIGURE 1.6 Process flow diagram for plastic recycling.

Thermosets

Thermosets are the second type of plastic products. Thermosets are formed by aid of the thermo plastics polymers when they covalently bonded to form chains that are interconnected and cross-linked to each other, and they differ from thermo plastics in that once they are formed with the aid of heat or pressure, they cannot be shaped or remelted again. The chain or the cross-link that forms the thermo sets occurs by the aid of some chemical reactions or due to heating or adding of a catalyst. The chemical reactions that are involved in producing the product are not reversible, and that's why it is so hard to reform it again. Once the product is converted from a liquid state to a solid state, it will be referred to as cure.

TABLE 1.1 Mechanical Properties for Thermosetting Plastics

Material

Tensile

Tensile

Compressive

Yield

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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