Everywhere and Nowhere:
An Introduction to Plastics
Dr Cameron Tonkinwise

The idea of "The Plastic Age" quickly disappeared like so many marketing pitches do. But this disappearance conceals the extent to which every environment we dwell in, every action we undertake, even most of the ways we think, all depend heavily on plastics. These days, our lifestyles are sustained by plastics. How can we possibly begin to determine the environmental impacts of this plastic world in which we are implicated? Looking at the life cycle of the material offers a starting point and a table which summarises the environmental impacts associated with the manufacture and disposal of the most commonly used plastics, is available on request to subscribers. However the greatest impacts associated with plastics arise before and after these details - that is, in the way we relate to plastics, and in the ways of living and working that plastic has made possible - rather than in the actual technical nature of the material.

Missing Plastic
We tend to ignore or forget about plastics yet they are literally everywhere. It is worthwhile anywhere, anytime, trying to identify all the plastics around you. Then it is worth thinking about why we don't notice these materials. Plastics tend to be like words on paper - we just move straight to reading the words on a page and have to force ourselves to think about the material ink on the wood-fibre paper. So we tend to only see an object, a tool, the contents of a package, rather than the plastic itself. It follows that we mostly don't notice the enormous environmental effects that this ubiquitous material actually generates.
There are a number of reasons for this:

Firstly, plastics can be transparent. Their success as a type of packaging has as much to do with letting us see products as it does with being lightweight, impervious, flexible or stiff. In this form, plastic has been purposely designed to disappear - its job is simply to display the product. Because of this we can use and throw plastic packaging away tens of times everyday without blinking, because we are focussed on the product (which in all probability is at least partially plastic as well!)

When plastics are opaque, they have a uniform appearance (especially when they attempt to mimic non-uniform materials). This sameness also encourages plastics to disappear from our attention. We don't think about the material, because there is nothing about a plastic's materiality that draws attention to itself. On the other hand, this is also the result of plastics' pervasiveness. The consistency of plastic was originally strange and very artificial, but we are now so accustomed to this absolutely regular material that it is second nature to us. 1 [End notes open in a seperate window.]

Whilst metals can share this uniform look with plastics, they seem to have more presence because of their weight. Plastics by contrast are inconspicuously light. Plastics are produced by complex, energy intensive processes, and the per kilo embodied energy of nearly all plastics is comparatively high. However, plastics are able to spread their properties very thinly. They are consequently the lightest common material available, with strength to weight ratios which cannot be found in any other material - something that made plastics seem very 'futuristic' when lightweight versions first became available. As Jeffrey Miekle in his cultural history of plastic describes, lightweight plastic was composed "...of insubstantial foams and films, of flexible vinyl and polyethylene rather than rigid polyester, the new 'plastic-as-plastic' design of the 1960s and 1970s promised do-it-yourself environments fully malleable in the hands of individuals - and so ephemeral as to be disposable." 2

These days however, the lightness of plastics contribute to their disappearance, allowing us to throw them away without feeling that anything substantial is being wasted. The plastics industry uses this argument to assert that the physical volume (when squashed by dirt, etc) and weight of plastics in landfill is quite modest compared with building rubble or even piles of newspapers. However, this fails to acknowledge just how much plastic we do still throw away everyday. 3

Most significantly in these economically driven times, plastic does not attract attention because it is so inexpensive. As a derivative of the petrochemical industry, plastics are almost subsidised by fuel consumption. More importantly, their low price is exemplary of what happens when you treat environmental costs as externalities: if the cost of plastics reflected the environmental degradation caused by their production and extensive disposal, they would be at least two to three times as expensive. 4  As it is, this gap between their market cost and their real cost is growing, because the cheapness of the former allows them to be consumed at rates that are blowing out the cost of the latter.
For all these reasons, plastics have tended to slip by unnoticed. Their proliferation has been made possible by our ignorance of them as a material, as products that consume resources and have major environmental impacts in their production and disposal.

What are Plastics?
Taking notice of plastics brings to our attention the extent to which we live in a world that we do not understand. Many of us have very little idea about what most of the things around us are made of - we certainly don't think of plastics as the products of complex chemical processes. Calling something plastic is almost a euphemism for having no idea how it was made, and therefore what its consequences are, environmental or otherwise.

Even chemical engineers can't differentiate some plastics by how they look or feel - especially since there has been a strong convergence of plastics competing for the same product-markets: eg an opaque bottle can be PET, HDPE, PVC, PP, even PS. Whilst most plastics are derived from the 'aromatics' (volatile organic compounds) of petroleum, they have been engineered so that the final products have no smell or taste - many of the most toxic mid-point compounds in the manufacture of plastics are dangerously odourless.

Further there are plastics now on the market that many of us would not even identify as plastics. New reinforced composites and invisible coatings and laminates (eg on aluminium foil, inside tins, on concrete surfaces, between glass panels, etc) demonstrate that the line between plastics, adhesives, and paints is losing definition. It is common these days to believe that the range of plastics is now so great that the term itself no longer has useful meaning.

Plastics are therefore a bit of an obstacle to our much needed environmental awareness - by which we mean noticing things in the environments we actually live and work in (perhaps even more than worrying about wilderness destruction). On top of this, there are some myths about plastics that tend to discourage us from investigating how they function in our environments and how we can start to develop a more informed relation to them:

For all the reasons so far discussed, plastics are thought to be very inert: nothing really rubs off and there is generally no smell. They are therefore thought to be very stable and hygienic in a range of temperatures and conditions. This is however not quite true. Plastics do bind most of their ingredients into stable matrixes; so whilst there are some toxic heavy metals added to plastics as stabilisers (to protect from UV, heat, oxidation, etc.), these generally cannot leach out of the material. Some key toxic ingredients of plastics are however not secure. Many of the monomers which are polymerised into plastic, do off-gas from the finished product. For instance, styrene, a hazardous neurotoxin that constitutes the basis of many plastics and composites (including fibre-glass), continues to emerge after production. 5

Most worryingly, the plasticisers (chemicals that make plastic flexible added to nearly all plastics, up to 50% of the total composition in some), do off-gas and leach from plastic products throughout their life. These plasticisers can function as synthetic oestrogens, disrupting human and animal endocrinic or hormonal systems. 6 Whilst the amount of synthetic oestrogen given off by any one plastic is not dangerous, oestrogen mimicking chemicals are bio-accumulative. This is of major concern given the number of plastics we are exposed to everyday, together with other sources of endocrine disrupters, like solvents and pesticides.

Soft plastics, especially plasticised PVC, which has one of the highest percentages of DEHP (the major synthetic oestrogen used in plastics), should be avoided for food or beverage storage, especially of fatty foods (eg meats and dairy products). Synthetic oestrogens are olephilic or 'oil loving'; they migrate toward and deposit themselves in fats. They are thus also drawn out by certain detergents, eg when washing plastics, thereby entering waste water streams.7

Despite the fact that nearly two thirds of plastics have a use-life of less than two years, we nonetheless often assume that plastics are almost indestructible. They often are amazingly long lasting. Everything that makes them very good packages, like their imperviousness, means that they are highly unbiodegradable and even intractable. While most can be broken down by various solvents and acids (see the design detail section of the table for the types of adhesives and paints that can be used with various plastics), most of these agents are themselves products of petrochemical manufacture. They are often more complex, energy intensive or dangerous than plastics manufacturing and are not naturally occurring (see the unfeasibility of recycling below).

Whilst plastics do remain in the environment, this does not mean that plastics remain functional. All plastics are degraded by types of oxidation, mechanical pressures (bends and impacts), changes in temperature and most significantly by ultra-violet radiation (which ironically is increasing in potency partially because of plastics manufacturing: see the section of the table on polyurethane). As with timber, as soon as a defect is introduced, no matter how small, it can undermine the structural integrity of the whole material (current R&D into 'intelligent' plastics involves filling plastics with unreacted beads of chemical, which, when split open by an age or stress fracture, react and repair the fracture with 'new' plastic resins).

Nearly all plastics depend on a range of stabilisers (complex heavy metal compounds, based on lead, nickel, zinc, barium, cadmium, but also calcium and phosphorous) to extend their useful-life against:

  • thermal oxidation, both during use-life, especially in the case of plastics designed for use in hot environments, but also during processing
  • photo-oxidation, ie., UV absorbers and quenchers
  • the inherent reactivity of some of the chemicals used in some plastics, like chlorine in PVC

Plastics like PVC and PP could not exist without the addition of stabilisers. Other optional additives for factors like anti-static can also be put in. In the case of PVC, the list of such additives is almost ridiculous: vinyl is inherently fire extinguishing, but added plasticisers make it flammable, so it contains fire-retardants, but because this then makes it smoke noxiously (with hydrochloric acid and even dioxins), anti-smoke additives are also used!

Many plastics also have other polymer laminates to further enhance durability and provide other features. Glass-reinforced plastic sheeting for instance can have UV protectant fluropolymer laminates, reflecting and insulating layers made out of metals, plus thick resins for protection from weather, eg hail.

However every plastic has a finite functional life. Well maintained (that is, kept out of the sun, out of extreme higher or lower temperatures and free from impacts or stresses), a plastic can retain its functional properties for anywhere from 10 years for the softer plastics like polyethylene, to 100 years for the harder plastics like PVC (see the table for the life-expectancy of different plastics). Exposed to any of these conditions, the use-life of plastics can halve or even quarter. This does not mean that the plastic breaks down into its constituent chemicals, but merely that the plastic product stops functioning with the properties for which it was designed.

Infinitely Remouldable
The most common plastics these days are 'thermoplastics'. As opposed to 'thermosets' (eg polyurethane: the foam in a mattress, or 'bakelite': one of the first most commonly used plastics) which get fixed into position on cooling and cannot be melted, a thermoplastic (eg polypropylene: an ice-cream tub) is, by definition, a plastic that can be cooled into one position, then later heated, melted and remoulded into a new position. This suggests - and plastics have been marketed this way - that plastics are infinitely reformable, the material most clearly designed for recycling.

The fact that plastics are thought to be limitlessly modifiable, and yet also totally permanent in their provisional forms (ie their current mould), should arouse suspicion. It is important to note that despite our 20th Century worldliness, plastic has succeeded in being a contemporary myth: the history of the development of plastic has been driven by the belief that there can be a perfect material, applicable to any situation. The truth of the matter is that structural integrity comes at the expense of re-mouldability. The same stabilising additives or laminates that give plastic its functional durability, prevent it from being readily reformed with only the addition of heat. Most plastics therefore, whilst being categorised as thermoplastics, achieve a certain permanence only by functioning more like thermosets, limiting the possibility for long term durability through re-manufacturing.

Continue on to the second half of this Article on Plastics