Plastic recycling is the process of restoring residual or plastic waste and reprocessing the ingredients into useful products. Since most of the plastics are not biodegradable, recycling is part of a global effort to reduce plastics in waste streams, especially about 8 million tons of plastic waste entering Earth's oceans each year.
Compared to profitable metal recycling, and similar to low value glass, recycling of plastic polymers is often more challenging due to low density and low value. There are also many technical hurdles to be overcome when recycling plastic.
When different types of plastics are melted together, they tend to separate phases, such as oil and water, and are arranged in these layers. Phase boundaries cause structural weakness in the resulting material, which means that the polymer blend is useful only in limited applications. The two most widely produced plastics, polypropylene and polyethylene behave this way, limiting their usefulness for recycling. More recently, the use of block copolymers as "molecular sutures" or "macromolecular welding fluxes" has been proposed to overcome difficulties associated with phase separation during recycling.
The percentage of fully recyclable plastic, instead of being recycled or disposed of in waste, can be increased when the packaged goods manufacturer minimizes the mixing of packaging materials and removes the contaminants. The Association of Plastics Recyclers has issued a "Design Guide for Recycling".
The use of biodegradable plastic is increasing.
Video Plastic recycling
Process
Before being recycled, most plastics are sorted by their resin type. In the past, reclaimed plastics use resin identification codes (RICs), a polymer type categorization method, developed by the Society of the Plastics Industry in 1988. Polyethylene terephthalate, commonly referred to as PET, for example, has resin code 1. Most plastic reclaimers do not relying on RIC now; they use automatic sorting systems to identify resins, ranging from manual sorting and plastic material retrieval to mechanical automation processes involving shredding, sieving, density based separation ie air, liquid, or magnetic distribution technology, and complex spectrophotometry, for example. UV/VIS, NIR, Laser, etc. Some plastic products are also separated by color before being recycled. The recyclable plastic is then shredded. These shredded pieces then undergo a process to remove impurities such as paper labels. This material is melted and often extruded into pellet form which is then used to produce other products.
Thermal depolarization
Plastic pyrolysis waste to fuel oil
Plastic pyrolysis can change the flow of petroleum-based waste such as plastics into fuel and carbon.
Given below is a list of plastic raw materials suitable for pyrolysis:
- Plastic blends (HDPE, LDPE, PE, PP, Nylon, Teflon, PS, ABS, FRP etc.)
- Plastic mixture of waste paper mill
- Plastics in layers
Hot compression
Heat compression takes all uncharted plastic, cleaned in all forms, from soft plastic bags to hard industrial waste, and mixes the load in a glass (a large rotating drum that resembles a giant clothes dryer). The most obvious benefit of this method is that all plastics can be recycled, not just matching shapes. However, criticism goes up from energy costs to rotate the drum, and heats the post-melting pipes.
Distributed recycling
For some plastic waste, a technical device called recyclebots allows a distributed recycling form. Early life cycle analysis (LCA) suggests that redistribution of such HDPE to make 3-D printer filaments in rural areas is particularly advantageous either using pure resin or conventional recycling processes due to a reduction in transport energy
Other processes
A process has also been developed in which various types of plastics can be used as carbon sources in recycled used steel. There is also the possibility of mixing of different plastic recyclables, which do not require their separation. This is called compatibilization and requires the use of special chemical compatibilizers. This can help to maintain the quality of recycled materials and often bypass expensive and inefficient initial scanning of the plastic waste stream and its separation/purification.
Maps Plastic recycling
Apps
PET
The post-consumer polyethylene terephthalate (PET or PETE) container is sorted into different color fractions, and is bound for subsequent sale. PET recyclers further sort the bottles that are released and they are washed and flaked (or flaked and then washed). Non-PET fractions such as hats and labels are removed during this process. Clean flakes are dried. Further treatment may be performed such as dilute screening and pellets or treatments to produce a contact-approved recycling PET (RPET).
RPET has been widely used to produce polyester fibers. This ordered post-consumer waste waste is destroyed, cut into shale, pressed into bales, and offered for sale.
One use for this recycled PET is to fabricate fabrics to be used in the apparel industry. Fabrics are made by spinning PET flakes into yarn and yarn. This is done as easy as making a polyester from a new PET. PET recycled yarn or yarn can be used alone or in conjunction with other fibers to create different types of fabrics. Traditionally, these fabrics are used to create strong, durable rugged products such as jackets, coats, shoes, bags, hats, and accessories as they are usually too rough for direct contact with skin and can cause irritation. However, this type of fabric has become more popular as a result of public awareness about environmental issues. Many fabric and clothing manufacturers have taken advantage of this trend.
Other major outlets for RPET are new containers (food contact or non-contact-food) manufactured either by (blow injection stretch) molding into bottles and jars or with APET thermoforming sheets to produce clam shells, blister packs and collector trays. This app uses 46% of all RPETs produced in Europe in 2010. Other applications, such as firm tape, injection molding technique components and building materials, accounted for 13% of RPET 2010 production.
In the United States, the recycling rate for PET packaging is 31.2% by 2013, according to a report from The National Association for Pet Container Resources (NAPCOR) and The Association of Postconsumer Plastic Recyclers (APR). A total of 1.798 million pounds were collected and 475 million pounds of recycled PET was used out of a total of 5,764 million pounds of PET bottles.
HDPE
Plastic # 2, high-density polyethylene (HDPE) is a plastic that is often recycled. These are typically recycled into plastics, tables, roadside sidewalks, benches, cargo truck liners, trash containers, stationery (eg rulers) and other durable plastic products and are usually in great demand.
PS
Most polystyrene products are not recycled because of the lack of incentives to invest in compactors and the necessary logistics systems. As a result, manufacturers can not obtain enough scraps. The expanded polystyrene slice (EPS) can be easily added to products such as EPS insulation sheets and other EPS materials for construction applications. When not used to make more EPS, foam scrap can be changed into clothes hanger, park bench, flower pot, toy, ruler, stapler body, seed container, photo frame, and architectural mold from recycling PS.
EPS recycling is also used in many metal casting operations. Rastra is made from EPS combined with cement to be used as a change of insulation in the manufacture of concrete and wall foundations. Since 1993, American manufacturers have produced an insulating concrete form made with about 80% recycled EPS.
Other plastics
White plastic polystyrene foam beans used as packing materials are often accepted by shipping stores for reuse.
Successful trials in Israel show that plastic films taken from a mixture of municipal sewage streams can be recycled into useful household products such as buckets.
Similarly, agricultural plastics such as mulch films, tape drops, and silage bags are diverted from waste streams and successfully recycled into much larger products for industrial applications such as plastic composite railway ties. Historically, agricultural plastics have been primarily stockpiled or burned on site on individual farmland.
CNN reports that Dr. S. Madhu from Kerala Highway Research Institute, India, has formulated a road surface that includes recycled plastics: aggregates, bitumen (asphalt) with plastic that has been shredded and melted at temperatures below 220 degrees C (428). Ã, Â ° F) to avoid pollution. This road surface is claimed to be very durable and rain resistant monsoon. Plastics are sorted by hand, which is economical in India. The test road uses 60 kg of plastic for a two meter long road, 8 meters wide, 8 meters wide. This process cuts the waste of thin film into thin flakes of small flakes that can be mixed with heat into the condensed asphalt with a special printing machine. Tests at the Indian and Bangalore Road Research Center show that roads built using this 'KK process' will have longer lifetime and better resistance to cold, heat, crack, and wrinkles, with a factor of three.
Recycling rate
The number of post-consumer recycled plastics has increased annually since at least 1990, but the level is far behind other items, such as newspapers (about 80%) and corrugated fiber boards (about 70%). Overall, post-consumer US plastic waste for 2008 is estimated at 33.6 million tonnes; 2.2 million tonnes (6.5%) were recycled and 2.6 million tonnes (7.7%) burned for energy; 28.9 million tons, or 85.5%, dumped in landfills.
Japan's waste plastic utilization rate reached 83% in 2014, up from 73% in 2006 and 39% in 1996, according to the country's Plastic Waste Management Institute.
Economic and energy potential
In 2008, PET prices fell from $ 370/ton in the US to $ 20 in November. PET prices have returned to their long-term average in May 2009.
Consumer education
United Kingdom
In the UK, the number of post-consumer plastics recycled is relatively low, in part due to the lack of recycling facilities.
The 2020 Plastic Challenge was established in 2009 by the plastics industry with the goal of engaging the British public in the national debate on the use, reuse and disposal of plastics, and hosting a series of online debates on its website framed around the waste hierarchy.
There are facilities in Worksop that are able to recycle 60-80 thousand tons per year.
Plastic identification code
Seven groups of plastic polymers, each with special properties, are used worldwide for packaging applications (see table below). Each group of plastic polymers can be identified by a plastic identification code (PIC), usually a number or letter abbreviation. For example, low-density polyethylene can be identified by the number "4" or "LDPE". The PIC appears in a three-chase-arrow recycling symbol. This symbol is used to indicate whether the plastic can be recycled into a new product.
The PIC was introduced by the Society of the Plastics Industry, Inc., to provide a uniform system for the identification of different types of polymers and to help recycling companies separate the various plastics for reprocessing. Manufacturers of plastic products are required to use PIC labels in some countries/regions and may voluntarily mark their products with PICs where there are no requirements. Consumers can identify types of plastics based on codes usually found on base or on the side of plastic products, including packaging/food/chemical containers. PICs are usually absent in packaging films, as it is not practical to collect and recycle most of these types of waste.
United States
The low national plastic recycling rate is caused by the complexity of sorting and processing, the unfavorable economy, and consumer confusion about which plastics can actually be recycled. Part of the confusion is due to the use of resin identification codes that are not on all plastic parts but only parts that include recycled symbols as part of the design. The resin identification code is stamped or printed at the bottom of the container and surrounded by an arrow triangle. (See table in Plastic.) The purpose of these symbols is to make it easier to identify the type of plastic used to make a particular container and to show that plastics are potentially recycled. The remaining questions are the types of plastics that can be recycled by the local recycling center. In many communities, not all types of plastics are accepted for recycling collection programs on the sidewalk because of the high processing costs and complexity of equipment needed to recycle certain materials. There is also sometimes low demand for recycled products depending on the proximity of the recycling center with entities that are looking for recycled materials. Another major obstacle is the cost of recycling certain materials and the appropriate market prices for those ingredients sometimes does not present a profit opportunity. The best example of this is polystyrene (commonly called styrofoam), although some communities, such as Brookline, Massachusetts, are moving toward banning the distribution of polystyrene containers by local food and coffee businesses.
See also
- Baler
- Bisphenol Articles about "CPA", specifically. relevant to type 3 & amp; 7 plastics
- Plastic processing economy
- Recycle glass
- Microplastic
- Take out a lightweight plastic bag
- 2020 Plastic Challenge
- Bottle reuse
References
External links
- West, Larry. "Recyclable Plastics: Why Are Some Food Containers Made of Recyclable Plastics?". About.com . Retrieved May 4 2009 .
- Plastic recycling value
- ISF Plastic Recovery Manual
Source of the article : Wikipedia
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