Pyrolysis of fluorocarbon polymers

Abstract

Th e t herm al deco mposition of variou s flu oro carbon p olymers were inv est iga,ted ; volatile p rodu cts of t he d ecomposition were d et ermined along with t he overall rates of volatili zation, a nd from t h ese rates t he acti vation energies were calculated for t he thermal deg radation r eactions. The t hermalJ y m ost stable of all t he poly mers t hus far st ud ied a re t he co mpletely flu orin ated o nes. H owever, e vid ence from a s t udy of t he dccomposition of h exafluorop ropy lene t elomers and from th e study of a copolym cr of t etra flu oroe thylene and hexafl uo ropropylene suggest s t hat the homopolymer of hexaflu o roprop ylene, if it co uld be m ad e, wou ld be quite unstable. The photoindu ced d ecomposi tion of polyt rifiu orochloroet hylene was also investigated , a nd estimates of t he activa tion energies wer e ob tain ed for the variou s elementar y step s of t he deco mposi tion m echanism:] Th e photoindu ced exp er imc nts indica ted that mu t ual termination of t he radical i nt erm ediates takes place and t hat a diff usion effect on d ep ropagation b cco mes pronoun ced below 250°C.

Gamma irradiation of fluorocarbon polymers

“…Representative types include PTFS (fluorocarbon main chain and hydrocarbon ring), PPFS (hydrocarbon chain an fluorocarbon ring), and polyperfluoropolyphenyl (perfluoroaromatic rings linked directly). The thermal stability of the latter two polymers appears to be good [ 38 , 39 ]. Further aromatic systems such as perfluorophenylene ethers may be possible.…”

“…Irradiation of the prototype molecule C 6 F 6 resulted in coupling to form polymer as the main reaction, and produced almost no inorganic fluoride or small molecules [ 10 ]. The triazine polymers developed by H. C. Brown [ 40 ] have a quasi-aromatic ring structure, and some examples are thermally stable [ 38 ], but no radiation data are known. Among the pure halocarbon polymers, PTFE offers special problems and will be considered later.…”

Pyrolysis of new fluoropolymers

“…The two new chloropeduoroheptadiene polymers showed relatively good stability properties even for a fluoropolymer containing a chlorine atom. The rate curves of the current polymers indicate greater stability and higher activation energies than noted for polychlorotrifluoroethylene (7,18,19).…”

“…Until recently, no perfluorohomopolymers other than polytetrafluoroethylene were available. Because of the high thermal stability of this linear fluoropolymer (1-6), additional research has been extended to the study of other linear, branched, and aromatic fluoropolymers (2,7,8). Relative thermal stability studies have established the superior stability of the perfluoropolymers over other fluoropolymers containing some hydrogen or chlorine atoms (2, 7 ) .…”

Thermal degradation of poly(1,1‐dichloro‐2,2‐difluoroethylene)

“…The thermal degradation of polychlorotrifluoroethylene has been investigated in s o m e detail (1)(2)(3)(4), and the stability shown to be about 15OoC lower than that of polytetrafluoroethylene. This may be attributed to the lower C-C1 bond strength, 81 kcal/mol compared with values of 86 kcal/mol for C-C bonds and 108 kcal/mol for C-F bonds (5).…”