Radiolysis of polymethyl isopropenyl ketone

Abstract

Polymethyl isopropenyl ketone (PMIPK) undergoes random chain scission when irradiated at 23°C. with gamma rays or with ultraviolet light. Total energy absorption per chain scission, Ed, is 94 e.v./scission for PMIPK powders irradiated in vacuo with spent reactor fuel element gamma rays (0.42 Mrad/hr.). Ed is 84 e.v./scission for a PMIPK powder irradiated in vacuo with Co60 gamma rays (0.109 Mrad/hr.). The presence of air lowers the value of Ed to 41 e.v./scission under the former conditions. A film of PMIPK irradiated in air with 2537‐A. wavelength light exhibits Ed = 22 e.v./scission or a quantum yield ϕd = 0.22 chain scissions/absorbed photon. The viscosity‐average molecular weights of this film vary with light exposure in accordance with theoretical predictions.

The interaction of 5 KeV electrons with polymers of methyl isopropenyl ketone

“…The lower quantum yields in the solid state for these copolymers compared with PMIPK photolysis (14) may be related to conformational effects in the polymers below T,.…”

“…Shultz (14) found that y-radiolysis of PMIPK at 23" proceeded more efficiently in air than in uacuo. Ultraviolet photolysis below T , using 254 nm light was shown (14) to proceed more efficiently than 7-radiolysis in either environment.…”

“…I ) has been known ( 11,12) at least since 1934. The photochemistry and y-radiolysis of this and of several structurally related polymers have been studied in recent years by several authors (13)(14)(15)(16)(17).…”

Polymerization of vinyl ketones

“…UV and gamma irradiation of poly(methy1 isopropenyl ketone) produced r mdom chain scission at 23°C. Unexpectedly, the presence of air incr:ased main-chain scission of the polymer under gamma irradiation (109).…”

Photolysis of poly(3‐buten‐2‐one), poly(4,4‐dimethyl‐1‐penten‐3‐one), and poly(3‐methyl‐3‐buten‐2‐one) in the presence of oxygen

“…The structures of the polymer POs produced from PBVK and PMIK were identified as peroxicarboxylic acid (F) and hydroperoxide (HI, respectively. It can be concluded that the POs are produced by the additions of oxygen with the a-cleavaged radicals, as follows [eqs (4). PBVK,and (5),PMIK]: the polymer PO led to the main chain degradation.…”