Study of degradation of polystyrene, using infrared spectrophotometry

Abstract

Sin ce p olystyrene is a widely used plastic a nd styrene is an in tegral part of t he m ost wid ely used sy nthetic r ubber (GR-S) , it appears necessary to k now somethi ng of the process of degrada t ion of polystyrene t o a ssist in in terpreting t he d egradation of these materi als in service. P olystyrene films were exposed to h eat at 100° C in a for ced-draft air oven a nd to ultraviolet ra di a nt e nergy at 60° C in air. Chemical st r uctural changes in t he polymer a s a resul t of t hese t reatments were a nalyzed b y st udy of t he infrared spectra between 2 a nd 16 microns , obtained wit h a Ba ird recording infra red spectrop ho tomete r. U lt rav iolet expos ure fo], 200 hours resulted in a bsorpt ions a t 2.9 and 5.8 microns, which a re attributed to hydroxyl a nd carbonyl groups, respectively. H eati ng of t he film for 270 hours at 100° C p rodu ced no signifi can t change in the infra red spectrum. P ro longed heating at. 125° C re-sul te d in t he dest r uction of t he films by £i ow. The literature and t heory o n t he d egrada t io n of p olys tyrene a re discussed. Several me cha nis ms are postu lated to a ccou nt for the p rod uc-tion of hydroxyl a nd carbonyl p rodu cts in t he p oly mer .