Thursday, July 10, 2008

Mixed feelings on PVC

My post the other day could give you the impression that I am in love with PVC. I am certainly not. Considering all the additives (plasticizers, UV and thermal stabilizers, internal/external lubricants, ...) that are needed (I did mention colorants as they are needed in all plastics) and the high levels of their addition, I've always felt that if PVC had been invented only last week, it would have been tossed aside as an academic curiosity.

It certainly is cheap. ~ 35 wt% of the polymer is tied up in chlorine atoms that are not a product of the petroleum industry so it is better able to weather price increases in crude oil. (Chlorinated PVC is even better situated with nearly twice the chlorine.) But I've always just found it a pain to work with, (the rheology of it is a nightmare compared to most thermoplastics or even thermosets) so that I have mixed feelings about the move away from it. I tepidly appreciate the move, but it is mostly being done for the wrong reasons such as the paranoia discussed previously. I find this disturbing as it rewards bad science, further encouraging more of it.

No comments: