Epoxidation of thermally degraded poly(vinyl chloride)

Abstract

Epoxidation of conjugated polyenes formed by thermal degradation of poly(vinyl chloride) (PVC) was carried out in cyclohexanone and tetrahydrofuran solution with m-chloroperoxybenzoic acid (mCPBA). PVC was thermally degraded in the solid state under continuous nitrogen flow at 200 °C for 30 min leading to 0.6 mol% double bonds in the polymer chain as determined from the UV-visible spectrum of the degraded polymer. Cyclohexanone proved to be an inappropriate solvent for the epoxidation reaction probably due to its competitive reaction with the peroxide. UV-visible and FTIR spectroscopic analyses indicate that the epoxidation of polyenes by mCPBA in THF occurs in high yields leading to polyepoxy sequences in the PVC chain, and there are no signs of side reactions, such as oxidation of double bonds in polyenes to carbonyl groups. To our knowledge this is the first report on epoxidation of polymers containing conjugated double bond sequences. The resulting new epoxidised PVC might be useful in a variety of applications, such as fully miscible secondary epoxy stabiliser for PVC itself without plasticising effect, starting material for epoxy curing and co-curing for reactive blends, etc.