li able . ▁ ▁Early ▁on , ▁the ▁health ▁and ▁environmental ▁aspects ▁of ▁this ▁were ▁poor ly ▁understood ▁and ▁rep lac ements ▁and ▁product ▁b ans ▁resulted ▁after ▁studies . ▁The ▁original ▁form ▁is ▁often ▁referred ▁to ▁as ▁un pl astic ized ▁poly vin yl ▁ch lor ide ▁( u P VC ), ▁which ▁is ▁the ▁more ▁commonly ▁used ▁type ▁for ▁install ations ▁such ▁as ▁water , ▁waste , ▁and ▁se wer ▁convey ance ▁pl umb ing . ▁ ▁Chem ical ▁modification ▁often ▁produces ▁more ▁dr astic ▁changes ▁in ▁properties . ▁Ch lor in ated ▁poly vin yl ▁ch lor ide ▁( CP VC ) ▁is ▁produced ▁through ▁expos ing ▁P VC ▁to ▁the ▁continued ▁free - rad ical ▁ch lor ination ▁reaction ▁that ▁originally ▁form ul ates ▁the ▁P VC ▁polym er . ▁The ▁ch lor ination ▁reaction ▁continues ▁to ▁add ▁ch lor ine ▁atoms ▁to ▁the ▁polym er ▁hydro car bon ▁back bone ▁until ▁most ▁commercial ▁applications ▁reach ▁a ▁percent ▁range ▁between ▁ 5 6 ▁and ▁ 7 4 % ▁total ▁ch lor ine . ▁This ▁increase ▁in ▁element al ▁ch lor ine ▁content ▁cont ributes ▁to ▁CP VC ' s ▁increased ▁expression ▁of ▁ch lor ine - based ▁characteristics , ▁such ▁as ▁chemical ▁dur ability , ▁resistance ▁to ▁ac ids , ▁bases , ▁and ▁sal ts ; ▁sus cept ibility ▁to ▁am mon ia - based ▁comp ounds , ▁a rom at ics , ▁est ers , ▁k et ones ; ▁chemical ▁stability ; ▁heat ▁energy ▁transfer ▁resistance . ▁CP