A common observation is “If PVC appeared on the market now, it would be rejected”
It is true that the basic poly(vinyl chloride), PVC, is unacceptably unstable to processing temperatures and to uv light. This results in discolouration in both cases. PVC was commercialised in the 1930s. There was little competition to PVC’s potentially useful set of properties and technologists quickly found innovative ways to minimise decomposition.
Mixing PVC with a plasticiser (high boiling solvent) not only reduced processing temperatures and the extent of decomposition but opened the way to a transparent flexible material which is still used widely in applications such as blood bags, cable insulation and flooring. The parallel innovation was to develop additives, at levels as low as 1% that protected PVC from decomposition. I studied the thermal decomposition of polyvinyl chloride for 3 years. So I hasten to add that PVC stabilisers were perfected without a real understanding of the chemistry of PVC decomposition.
The other reason why polyvinyl chloride would fail now is its association (unfairly) with the villain of pressure groups, chlorine. Recently the polyvinyl chloride producers addressed the negative attitudes towards polyvinyl chloride by cleaning up the polymerisation even more. This was done by phasing out additives perceived to be hazardous by environmentalists and creating an impressive scheme for recycling polyvinyl chloride. In doing so polyvinyl chloride has regained its status as a major contributor towards modern society and safeguarding the environment.
If you shine a uv light on a polyvinyl chloride product just before the stabiliser is about to run out of protection, it will fluoresce green. Has anyone exploited this test?
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