Plastics Recycling Information

Number 6 Plastics -- PS (polystyrene)�

Number 7 Plastics - Miscellaneous (Other)

Found In: Three- and five-gallon water bottles, ‘bullet-proof‘ materials, sunglasses, DVDs, iPod and computer cases, signs and displays, certain food containers, nylon, auto parts

Recycling: Number 7 plastics have traditionally not been recycled, though some curbside programs now take them.�
Recycled Into: Plastic lumber, custom-made products


There are 4 type:
1. SAN � styrene acrylonitrile
2. ABS � acrylonitrile butadiene styrene
3. PC � polycarbonate
4. Nylon

SAN and ABS has a high resistance to chemical and temperature,normally exist in the mixer,wrapping flasks, dishes, cutlery, coffee filters, and toothbrush.
ABS is commonly used as lego and pipes
PC - or Polycarbonate can be found in baby bottles, toddler cups (sippy cup), polycarbonate drinking bottles and food packaging and beverage cans, including infant formula cans.

A wide variety of plastic resins that don‘t fit into the previous categories are lumped into number 7. A few are even made from plants (polyactide) and are compostable.

Polycarbonate is number 7, and is the hard plastic that has parents worried these days, after studies have shown it can leach potential hormone disruptors, chromosomes� in the ovaries, decreased sperm production, and alter immune function because PC can release the main material , Bisphenol-A c into the food.

 

Recycling plastics is easy.
First, you should learn what types of plastics can be recycled and only give your collector those types of plastics. Resist the temptation to slip plastics that recyclers don't want into the recycling bin.

Plastics have different formulations and should be sorted before they are recycled to make new products. Mixed plastics can be recycled, but they are not as valuable as sorted plastics because the recycled plastic's physical properties, such as strength, may vary with each batch.
Once you know what kinds of plastics your recycler wants, you should follow the wash and squash rule - rinse the container and squash it. You may leave the paper labels on the container, but throw away the plastic caps. Plastic caps are usually made from a different type of plastic than the container and cannot be easily recycled. Energy to burn.
Because plastics are made from fossil fuels, you can think of them as another form of stored energy. Kilogram for kilogram, plastics contain as much energy as petroleum or natural gas, and much more energy than other types of garbage. This makes plastic an ideal fuel for waste-to-energy plants.
Waste-to-energy plants burn garbage and use the heat energy released during combustion to make steam or electricity. They turn garbage into useful energy. So, should we burn plastics or recycle them? It depends. Sometimes it takes more energy to make a product from recycled plastics than it does to make it from all-new materials. If that's the case, it makes more sense to burn the plastics at a waste-to-energy plant than to recycle them. Burning plastics can supply an abundant amount of energy, while reducing the cost of waste disposal and saving landfill space.

How are plastics recycled?
A recycling plant uses seven steps to recycle plastic waste:
1. Inspection Workers inspect the plastic waste for contaminants like rock and glass, and for plastics that the plant cannot recycle.
2. Chopping & Washing The plastic is washed and chopped into flakes.
3. Floatation Tank If mixed plastics are being recycled, they are sorted in a flotation tank, where some types of plastic sink and others float.
4. Drying The plastic flakes are dried in a tumble-dryer.
5. Melting The dried flakes are fed into an extruder, where heat and pressure melt the plastic. Different types of plastics melt at different temperatures.
6. Filtering The molten plastic is forced through a fine screen to remove any contaminants that slipped through the washing process. The molten plastic is then formed into strands.
7. Pelletizing The strands are cooled in water, then chopped into uniform pellets which can be used to make new products. Recycled plastics can be made into many products, including flowerpots, lumber substitutes and carpeting.

Plastic recycling is the process of recovering scrap or waste plastics and reprocessing the material into useful products, sometimes completely different from their original state.
Before recycling, plastics are sorted according to their resin identification code. PET, for instance, has a resin code of 1.

Processing
When compared to other materials like glass and metal materials, plastic polymers require greater processing to be recycled.Plastics have a low entropy of mixing, which is due to the high molecular weight of their large polymer chains. A macromolecule interacts with its environment along its entire length, so its enthalpy of mixing is large compared to that of an organic molecule with a similar structure. Heating alone is not enough to dissolve such a large molecule; because of this, plastics must often be of nearly identical composition in order to mix efficiently.

When different types of plastics are melted together they tend to phase-separate, like oil and water, and set in these layers. The phase boundaries cause structural weakness in the resulting material, meaning that polymer blends are only useful in limited applications.

Another barrier to recycling is the widespread use of dyes, fillers, and other additives in plastics.
The polymer is generally too viscous to economically remove fillers, and would be damaged by many of the processes that could cheaply remove the added dyes. Additives are less widely used in beverage containers and plastic bags, allowing them to be recycled more frequently.

The use of biodegradable plastics is increasing. If some of these get mixed in the other plastics for recycling, the recycled plastic is less valuable.

Many such problems can be solved 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.

Another potential option is 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. Gasification is a similar process, but is not technically recycling since polymers are not likely to become the result.

Recently, 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.

Yet another process that is gaining ground with startup companies (especially in Australia, United States and Japan) is heat compression. 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. But criticism rises from the energy costs of rotating the drums, and heating the post-melt pipes.

Recycling of PET bottles
Post-consumer PET is often sorted into different color fractions. This sorted post-consumer PET waste is crushed, pressed into bales and offered for sale to recycling companies. PET flakes are used as the raw material for a range of products that would otherwise be made of polyester.

PVC recycling
PVC- or Vinyl Recycling has historically been difficult to perfect on the industrial scale. But within the last decade several viable methods for recycling or upcycling PVC plastic have been developed.

The most-often recycled plastic, HDPE or number 2, is downcycled into plastic lumber, tables, roadside curbs, benches, truck cargo liners, trash receptacles, stationery (e.g rulers) and other durable plastic products and is usually in demand.

The white plastic foam peanuts used as packing material are often accepted by shipping stores for reuse.

In Israel successful trials have shown that plastic films recovered from mixed municipal waste streams can be recycled into useful household products such as buckets.
Similarly, agricultural plastics such as mulch film, drip tape and silage bags are being diverted from the waste stream and successfully recycled into much larger products for industrial applications such as plastic composite railroad ties. Historically, these agricultural plastics have primarily been either landfilled or burned on-site in the fields of individual farms.

CNN reports that Indian Dr. S. Madhu of the Kerala Highway Research Institute has formulated a road surface that includes recycled plastic.[citation needed] Aggregate, bitumen (asphalt) with plastic that has been shredded and melted at a temperature below 220 degrees C to avoid pollution. This road surface is claimed to be very durable and monsoon rain resistant. The plastic is sorted by hand, which is economical in India. The test road used 60 kg of plastic for an approx. 500m long, 8m wide, two-lane road. Since the US annually uses 100 million metric tons of plastic, it could pave 1.67 billion km of single-lane road this way.

Plastic recycling rates lag far behind those of other items, such as newspaper (about 80%) and cardboard (about 70%). Low national plastic recycling rates have been due to the complexity of sorting and processing, unfavorable economics, and consumer confusion about which plastics can actually be recycled. Part of the confusion has been due to the recycling symbol that is usually on all plastic items. This symbol is called a resin identification code. It is is stamped or printed on the bottom of containers and surrounded by a a triangle of arrows. The intent of these arrows was to make it easier to identify plastics for recycling. The recycling symbol doesn’t necessarily mean that the item will be accepted by residential recycling programs.

In the UK, the amount of post-consumer plastic being recycled is relatively low, due in part to a lack of recycling facilities.
Plastic Identification Code
Seven groups of plastic polymers, each with specific properties, are used worldwide for packaging applications . Each group of plastic polymer can be identified by its Plastic Identification code (PIC) - usually a number or a letter abbreviation. For instance, Low-Density Polyethylene can be identified by the number 4 and/or the letters "LDPE". The PIC appears inside a three-chasing arrow recycling symbol. The symbol is used to indicate whether the plastic can be recycled into new products.

The PIC was introduced by the Society of the Plastics Industry, Inc. which provides a uniform system for the identification of different polymer types and helps recycling companies to separate different plastics for reprocessing. Manufacturers of plastic products are required to use PIC labels in some countries/regions and can voluntarily mark their products with the PIC where there are no requirements. Consumers can identify the plastic types based on the codes usually found at the base or at the side of the plastic products, including food/chemical packaging and containers. The PIC is usually not present on packaging films, as it is not practical to collect and recycle most of this type of waste.

Plastic Recycling

Obstacles
When compared to glass or metallic materials, plastic poses some unique challenges from a recycling perspective. Chief among them is their low entropy of mixing, which is due to the high molecular weight of large polymer chains. Another way of stating this problem is that, since a macromolecule interacts with its environment along its entire length, its enthalpy of mixing is very, very large compared to that of a small organic molecule with a similar structure; thermal excitations are often not enough to drive such a huge molecule into solution on their own. Due to this uncommon influence of mixing enthalpy, polymers must often be of nearly identical composition in order to mix with one another. To take representative samples from beverage containers, the many aluminium-based alloys all melt into the same liquid phase, but the various copolymer blends of PET from different manufacturers do not dissolve into one another when heated. Instead, they tend to phase-separate, like oil and water. Phase boundaries weaken an item made from such a mixture considerably, meaning that most polymer blends are only useful in a few, very limited contexts.

Another barrier to recycling is the widespread use of dyes, fillers, and other additives in plastics. The polymer is generally too viscous to economically remove fillers, and would be damaged by many of the processes that could cheaply remove the added dyes. Additives are less widely used in beverage containers and plastic bags, allowing them to be recycled more frequently.

The use of biodegradable plastics is increasing. If some of these get mixed in the other plastics for recycling, the recycled plastic is less valuable.