Top Richtlinien plastic
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^ 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
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 hinein certain environments.[54] Recent studies have shown, however, that plastics hinein the ocean decompose faster than had been previously thought, due to exposure to the sun, rain, and other environmental conditions, resulting hinein the release of toxic chemicals such as bisphenol A.
Most plastics contain organic polymers.[10] The vast majority of these polymers are formed from chains of carbon atoms, with or without the attachment of oxygen, nitrogen or sulfur atoms. These chains comprise many repeating units formed from monomers. Each polymer chain consists of several thousand repeating units. The backbone is the parte of the chain that is on the main path, linking together a large number of repeat units.
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]
A literature study made in 2022 by geologist student Björn Lycke shows that the amount of microplastics rein sediment is increasing worldwide, especially hinein ports and tourist beaches.[82]
Plastics are produced hinein chemical plants by the polymerization of their starting materials (monomers); which are almost always petrochemical rein nature. Such facilities are normally large and are visually similar to oil refineries, with sprawling pipework running throughout. The large size of these plants allows them to exploit economies of scale.
Some companies produce biodegradable additives to enhance biodegradation. Although starch powder can Beryllium added as a filler to allow some plastics to degrade more easily, such treatment does not lead to complete breakdown. Some researchers have genetically engineered bacteria to synthesize completely biodegradable plastics, such as polyhydroxy butyrate (PHB); however, these were tonlos relatively costly as of 2021.[23]
Additives are chemicals blended read more into plastics to change their performance or appearance, making it possible to alter the properties of plastics to better suit their intended applications.[31][32] Additives are therefore one of the reasons why plastic is used so widely.
Companies that produce finished goods are known as converters (sometimes processors). The vast majority of plastics produced worldwide are thermosoftening and must Beryllium heated until molten in order to be molded. Various sorts of extrusion equipment exist which can then form the plastic into almost any shape.
Traditionally derivatives of lead, cadmium & tin. Safer modern alternatives include barium/zinc mixtures and calcium stearate, along with various synergists
Light activated resin – resin that cures when exposed to light of appropriate wavelengthsPages displaying wikidata descriptions as a fallback
Self-healing plastic – Substances that can repair themselvesPages displaying short descriptions of redirect targets
Pre-exposure of the plastic to ultraviolet radiation broke chemical bonds and aided biodegradation; the longer the period of UV exposure, the greater the promotion of the degradation.[96]
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 rein order to Zusammenstellung bekannter melodien-in the additives.
Almost all recycling is mechanical and involves the melting and reforming of plastic into other items. This can cause polymer degradation at the molecular level, and requires that waste Beryllium sorted by colour and polymer type before processing, which is often complicated and expensive.