Why does the plastic PVC continue to be promoted for all kinds of applications, PP has many more advantages than disadvantages?

Answer

Best

To call PVC an outdated plastic is to be very short-sighted. There are many applications for which PVC is the most suitable plastic (and PP is not).

When you look at the molecular structure of PVC (and compare it with PP), these fall under the Chlorine groups. These groups are also the reason for the very specific properties of PVC, which, for example, PP does not possess.

Due to the strong electronegative value of Chlorine, ‘charge differences’ arise along the chain. The chlorine group is negatively charged, the tertiary C atom will be positively charged. If you now put 2 PVC chains next to each other, it makes sense that they will align until the positive and negative charges attract each other. There are, as it were, magnets between the different chains. With PP you have this to a much lesser extent. As a result, PVC is much stiffer than PP.

In addition, the high electronegative value of PVC also ensures very good fire properties. PVC is self-extinguishing because the chlorine groups attract the electrons so strongly, with the result that they are not available for the combustion process. For the same reason, the chemical resistance and weather resistance for PVC is much better than for PP.

A final important point with PVC is its unique ability to gel. This is especially useful when rotational molding a PVC paste (plastisol). Due to the gel effect, the viscosity increases with increasing temperature. From a certain temperature, the PVC paste has become a solid. At this point, the rotation can stop and further cooling occurs when the mold is stationary. This is not possible with other thermoplastics and simplifies installation.

You notice that PVC has some characteristic properties that cannot simply be taken over by another plastic. That is why PVC occupies an important place in the plastic world. Incidentally, the environmental problem is mainly related to the additives and stabilizers used. Several studies are currently being conducted on these additives in response to the REACH directive.