Effects of radiation on styrene and α‐methyl styrene in aqueous solution. A study by pulse radiolysis

Abstract

Diluted aqueous solutions of styrene and a-methyl styrene were irradiated with 2 psec pulses of 4 MeV electrons. The absorption spectra of transient species formed under irradiation were taken and kinetic studies on the decay of the absorptions were carried out. From the intluence of various additives on the absorption spectra and from the kinetic data obtained we conclude that the absorption a t 345 my for styrene and a t 350 my for a-methyl styrene is due to radicals formed by addition of OH* to the aromatic ring. The decay of the substituted hydroxycyclohexadienyl follows a second order kinetics with a rate constant of k rn 109 1:mole-1 sec-1.The long-lived UV-absorption with maxima a t 305 mp and 320 mp we attribute to the polymerizing styrene radical with the structure of a sabstituted benzyl. Such radicals can be formed by electron attachment to the styrene followed by rapid protonation, and by addition of He and OH* to the vinyl double bond. ZUSAMMENFASSUNG:Verdiinnte wil3rige Styrol-und a-Methylstyrol-Losungen wurden mit einem Elektronenstrahl (4 MeV) kurzzeitig (2 pec) bestrahlt. Es wurden die Absorptionsspektren der unter Bestrahlung gebildeten Spezies aufgenommen und kinetische Untersuchungen iiber das Abklingen der Absorption vorgenommen. Hieraus sowie aus dem EinfluD, den zugesetzte Substanzen auf die Absorptionen ausiiben, wird geschlossen, dal3 die Absorptionsbanden bei 345 m p (Styrol) bzw. 350 mp (a-Methylstyrol) Radikalen zuzuschreiben sind, die durch Addition von OHan den aromatischen Ring der Monomeren entstanden sind. Diese substituierten Hydroxycyclohexadienyl-Radikale verschwinden in einer Reaktion 2. Ordnung mit einer Geschwindigkeitskonstante k rn 109 Z.mol-l sec-1.

Modification of poly(vinyl chloride). XXIX. Cross linking of poly(vinyl chloride) with 2‐dibutylamino‐4,6‐dithiol‐s‐triazine and MGO

“…In Table I The practical crosslinking rate of PVC, as well as that of rubber vulcanization, could be obtained on the crosslinking at a higher temperature than 175OC. Since PVC decomposes at a higher temperature than 190°C (12) and discolors rapidly, it is desirable to carry out crosslinking in the temperature range 175-185°C for the present crosslinking compounds.…”

Recent Results From Pulse Radiolysis

“…Pulse radiolysis of a cyclohexane solution of styrene provides no evidence for a styrene triplet, but shows absorption bands at -400 and -320 nm. It was at first thought that the absorption at 400 nm was due to a free radical [28], but it is now believed that it is due to a styrene anion [29]. The band at -320 nm is believed to be due to a large extent to a substituted benzyl radical formed by protonation of the styrene anion.…”

Pulse Radiolysis Study on Radical Ions of Styrene

“…Schneider and Swallow examined bulk styrene and styrene solution in cyclohexane and found the absorption due to polymerizing radicals <,1max=320 nm) and that of radical anions (Amax=390 nm). 6 Transient absorptions were observed also in solutions of dioxane, tetrahydrofuran, 6 tetrachloromethane, aliphatic alcohol,7 and water. 6 However, evidence of cationic species of styrene has not yet been obtained by this technique;…”

“…6 Transient absorptions were observed also in solutions of dioxane, tetrahydrofuran, 6 tetrachloromethane, aliphatic alcohol,7 and water. 6 However, evidence of cationic species of styrene has not yet been obtained by this technique;…”