Waste plastic, even if it is all of the same polymer type, will contain varying types and amounts of additives. Mixing these together can give a material with inconsistent properties, which can be unappealing to industry. For example, mixing different colored plastics with different plastic colorants together can produce a discolored or brown material and for this reason plastic is usually sorted by both polymer type and color before recycling.[2]
Rein some cases, this can involve mixing different types of plastic together to form a polymer blend, such as high impact polystyrene. Large companies may do their own compounding prior to production, but some producers have it done by a third party. Companies that specialize rein this work are known as Compounders.
Rein around 1600 BC, Mesoamericans used natural rubber for balls, bands, and figurines.[4] Treated cattle horns were used as windows for lanterns rein the Middle Ages. Materials that mimicked the properties of horns were developed by treating milk proteins with lye. Hinein the nineteenth century, as chemistry developed during the Industrial Revolution, many materials were reported. The development of plastics accelerated with Charles Goodyear's 1839 discovery of vulcanization to harden natural rubber.
High-performance plastics are usually expensive, with their use limited to specialized applications which make use of their superior properties.
While a finished plastic may be non-toxic, the monomers used hinein the manufacture of its parent polymers may be toxic. Hinein some cases, small amounts of those chemicals can remain trapped hinein the product unless suitable processing is employed.
However they are tonlos routinely found hinein some plastic packaging including food packaging. The use of the additive bisphenol A (BPA) hinein plastic baby bottles is banned hinein many parts of the world, but is not restricted rein some low-income countries.[2]
A literature study made rein 2022 by geologist student Björn Lycke shows that the amount of microplastics rein sediment is increasing worldwide, especially rein ports and tourist beaches.[82]
The success and dominance of plastics starting rein the early 20th century has caused widespread environmental problems,[3] due to their slow decomposition rate rein natural ecosystems. Most plastic produced has not been reused, or is incapable of reuse, either being captured hinein landfills or persisting in the environment as plastic pollution and microplastics.
Because the chemical structure of most plastics renders them durable, they are resistant to many natural degradation processes. Much of this material may persist for centuries or longer, given the demonstrated persistence of structurally similar natural materials such as Bernsteinfarben.
Silicones (polysiloxanes): heat-resistant resins used mainly as sealants but also used for high-temperature cooking utensils and as a base resin for industrial paints
The concentrations of most additives are usually quite low, however high levels can be added to create Masterbatch products. The additives in these are concentrated but tonlos properly dispersed hinein the host resin.
Plastic pollution can be found hinein all the world's major water bodies, for example, creating garbage patches rein 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]
Microbial communities isolated from soil samples mixed with starch have been shown to Beryllium capable read more of degrading polypropylene.[92]
Masterbatch granules can Beryllium mixed with cheaper bulk polymer and will release their additives during processing to give a homogeneous final product. This can Beryllium cheaper than working with a fully compounded material and is particularly common for the introduction of color.
Additives can also Beryllium problematic if waste is burned, especially when burning is uncontrolled or takes place rein low- technology incinerators, as is common hinein 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]