The first stage in plastic production, the polymerisation of raw material.
Then substances such as fillers and chemicals (sometimes called monomeric ingredients), are added to give color, texture and a whole range of other qualities. Reinforcing fibers for example make the base polymer stronger while man-made organic chemicals, such as phthalates are added to make plastic flexible, resilient and easier to handle.
These give the plastic an additional range of qualities. There are thousands of addatives used in making plastic.
Reinforcing fibers to make the base polymer stronger. For example baron, carbon, fibrous minerals, glass, Kevlar all Increases tensile strength. Others increase flexibility, heat-deflection temperature (HDT) or help resists shrinkage and warpage.
Extender fillers such as calcium carbonate and silica, clay reduces material cost.
Conductive fillers means electromagnetic shielding property can be built into plastics, which are normally poor electrical conductors include aluminum powders, carbon fiber, graphite Improves electrical and thermal conductivity.
Coupling agents such as Silanes, titanates improve the bonding of the plastic matrix and the reinforcing fibres.
Plasticizers – man-made organic chemicals, such as phthalates added to make plastic flexible, resilient and easier to handle. Some are considered unsafe – read more here.
Stabilizers (halogen stabilizers, antioxidants, ultraviolet absorbers, and biological preservatives) to stop it breaking down over time>Protects from thermal and UV degradation (with carbon blacks).
Processing aids (ie lubricants to reduce the viscosity of the molten plastic and others)
Flame retardants Chlorine, bromine, phosphorous, metallic salts Reduces the occurrence and spread of combustion.
Anti-static agents can be used to attract moisture, reducing the build-up of static charge.
Colorants (pigments and dyes) Metal oxides, chromates, carbon blacks.
Blowing agents Gas, azo compounds, hydrazine derivatives Generates a cellular form to obtain a low-density
As you can see that is a lot of additives. So many that we do not know what they all are. Also manufacturers are not obliged to reveal what they use in their plastic mixes. So while the polymers used in base plastics are mostly considered to be harmless, the potential toxicity of the additives is often unknown.
It is claimed that many of the additives used have not been passed as fit for human consumption and that more research needs to be done on the safe handling and ultimate disposal of these plastics.
Rather worryingly, some of the chemicals used in plastic seem to be mobile and can leach from the plastic product into the contents. For example from the plastic packaging wrapped round your cheese or the epoxy resin lining of your can of beans into your food. The jury is still out on wether this is dangerous or not but add that to a brown toast cancer scare and cheesy beans don’t look so tasty!
Halogenated plastics like PVC will, when burnt, release dioxin one of the most powerful carcinogens known.
More animals are being found with plastic in their stomachs having mistaken for food and microplastics are being ingested by bottom feeders and plankton. Some reports claim that chemicals from plastic are being absorbed by animals with ill effects.You can read more on microplastic here and read reports on animals eating plastic.
Plastic particles attract persistent organic Pollutants (POPs). POPs are a small set of toxic chemicals that remain intact in the environment for long periods and accumulate in the fatty tissues of animals. Bottom feeders eat the plastic pellets and so the POPs enter the food chain.