Re-use, recycling and degradation of composites
Incineration of polymers
of plastics and composites is the opposite to the above, in the sense that it involves annihilation of the material, with inevitable air and land pollution, due to poor combustion and to gaseous/liquid/solid products of the process. Around 1 million tonnes of plastic materials are incinerated in the USA alone annually, and 11 % of the present total is poly(vinyl chloride). Western Europe generates around 100 million tonnes of municipal solid waste annually, with 7% being plastics. Of that part, 30% is disposed of by
@DanKaszeta When you're back at it, can you talk about: 1) WWI chem munitions storage in Spring Valley 'hood in DC 2) what is it about the actual demil process (incineration or otherwise) that is really not tolerant of power outages? demil sites ive seen— Bilsko (@SteamPoweredDM) Dec 18, 2021
incineration with and without energy recovery and 70% by landfilling. The polymer matrix resins used in composites possess higher calorific values (30 000
kJ/kg) than coal (26 000–30 000
The presence of non-combustible fillers and reinforcements reduces the calorific content down to 15 000
kJ/kg. The rate of combustion of plastics is determined by parameters such as surface to volume ratio, density, ignition point, combustion rate, etc. The flammability parameter, defined as the ratio of the heat of combustion divided by the heat required to produce volatiles, which in turn promotes ignition, is used for quantitative analysis of solid fuels. According to this characteristic, polypropylene and polystyrene have combustion performance comparable to wood. Some advantages of an increased content of plastic waste for incineration have been listed as: (i) higher temperature of incineration due to volatiles, which reduce leachability of the fly ash and (ii) shorter combustion zones and more intensely burning fire. Particular disadvantages from increased plastic waste are: (i) increased formation of NO
with an increase in incinerating temperatures, which automatically contradicts the above listed advantages, (ii) increased CO emissions, and (iii) other excessive emissions such as chlorine, dioxins and furans.
In general, there is no policy to support increased implementation in incineration of synthetic materials and this process is widely used only because other avenues of re-use and re-processing have not yet been fully explored.