Thermal degradation of polymers as a function of molecular structure

heated in a vacuum at temperatures of about 200 0 to 500 0 C, p oly mer chains break p into volatile fragments of various sizes, dependin g on t l1 e natu re of l ll e polymer.Som e ,Joly mers, like pol y -alpha-meth ylstyrene, y ield the monomer exclusively.Other polymers, like polymethylene, yield a whole spectrum of fragm e nts co nsis tin g of 2 carbon aloms in the chain to about 50 or more.Intermediate between these two lypes of p olymers arc those like polyiso butylene, which yield partly monom er and parlly large fragmenls .The rates at wh ich t hese fragments are formed and vaporized also vary for diffe re nt polyme rs.On cr 'l)arin g rates of volatilization of a series of poly me rs at 350 0 C, we find lhat polytetr a t, .. oroeth ylene is t he most therm aliy stable polymer, havin g an init ial rale of volalilization o. 0.0000016 weight percent p er minu te, wherea s poly-alpha-meth ylstyrene is the least ., ,, 1 "av ing a rate of volatilization of 230 p ercen t p er minute.These differences in t h e , behavior of polymers can be correlated with t he molec ular struc ture of the polymer ~nd II'i th the nat ure and frequ ency of s id e groups.