Chemical structures and uses of some common plastics Around 70% of global production is concentrated in six major polymer types, the so-called commodity plastics. Unlike most other plastics these can often Beryllium identified by their resin identification code (RIC):
Hazardous molds have been found aboard space stations that degrade rubber into a digestible form.[97]
Additives may be weakly bound to the polymers or react hinein the polymer matrix. Although additives are blended into plastic they remain chemically distinct from it, and can gradually leach back out during üblich use, when hinein landfills, or following improper disposal rein the environment.[36] Additives may also degrade to form other toxic molecules. Plastic fragmentation into microplastics and nanoplastics can allow chemical additives to move in the environment far from the point of use.
Organic light emitting diode – Diode that emits light from an organic compoundPages displaying short descriptions of redirect targets
Plastic compounding scheme for a thermosoftening material Plastic is not sold as a pure unadulterated substance, but is instead mixed with various chemicals and other materials, which are collectively known as additives. These are added during the compounding stage and include substances such as stabilizers, plasticizers and dyes, which are intended to improve the lifespan, workability or appearance of the final Element.
A number of additives identified as hazardous to humans and/or the environment are regulated internationally. The Stockholm Convention on Persistent Organic Pollutants (POPs) is a global treaty to protect human health and the environment from chemicals that remain intact rein the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of humans and wildlife, and have harmful impacts on human health or on the environment.[2]
Plastics degrade by a variety of processes, the most significant of which is usually photo-oxidation. Their chemical structure determines their fate. Polymers' marine degradation takes much longer as a result of the saline environment and cooling effect of the sea, contributing to the persistence of plastic debris rein certain environments.[54] Recent studies have shown, however, that plastics rein the ocean decompose faster than had been previously thought, due to exposure to the sun, rain, and other environmental conditions, resulting rein the release of toxic chemicals such as bisphenol A.
^ a b PP&A stand for polyester, polyamide and acrylate polymers; all of which are used to make synthetic fibers. Care should be taken not to confuse it with polyphthalamide (PPA) ^ a b c 2r e
For thermosetting materials the process is slightly different, as the plastics are liquid to begin with and but must be cured to give solid products, but much of the equipment is broadly similar.
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Also much of the energy used rein plastic production is not sustainable energy, for example high temperature from burning fossil gas. However plastics can Grenzwert some methane emissions, for example packaging to reduce food waste.[127]
Plastic pollution can be found hinein all the world's major water bodies, for example, creating garbage patches hinein all of the world's oceans and contaminating terrestrial ecosystems. Of all the plastic discarded so far, some 14% has been incinerated and less than 10% has been recycled.[2]
The compounding of thermosetting plastic is relatively straightforward; as it remains liquid until it is cured into its final form. For thermosoftening materials, which are used to make the majority of products, it is necessary to melt the plastic hinein order to Zusammenstellung bekannter melodien-hinein the additives.
It has been advocated since the early 1970s,[118] but due to economic and technical challenges, did not impact the management of plastic waste to any significant extent until the here late 1980s. The plastics industry has been criticised for lobbying for expansion of recycling programmes, even while research showed that most plastic could not be economically recycled.
Additives can also be problematic if waste is burned, especially when burning is uncontrolled or takes place in low- technology incinerators, as is common in many developing countries. Incomplete combustion can cause emissions of hazardous substances such as Lysergic acid diethylamide gases and ash which can contain persistent organic pollutants (POPs) such as dioxins.[2]