r 2 r 3 r 5 and r 6 h and r 4 br y bf 4 u2212 and the salts s4 1 s4 2 and s4 3 shown in fig4 the substituents on the benzene rings were in the para position each of said salts e previously dissolved to approximately 25 by weight in a solvent in particular propylene carbonate was present in an amount of 3 by weight relative to the total weight of the polymerisable composition co initiators b hydrogen peroxide h 2 o 2 b1 isobutylvinylether b2 4 mercaptophenol b3 photosensitizer c phenothiazine c1 i u2014 various polymerisable compositions in accordance with the invention were subjected to irradiation without adding external heat to said compositions i e at ambient temperature the proportion by weight of cationic salt relative to the total weight of the polymerisable composition in this case 1 gram g was 3 regardless of whether the salt was s1 1 the salt s3 1 or irgacure 250 which is an iodonium salt the proportions by weight of the co initiator b1 and of the co initiator b2 relative to the total weight of the polymerisable composition were respectively 3 and 1 the proportion by weight of photosensitizer c1 relative to the total weight of the polymerisable composition was 1 the irradiation lamp was a hamamatsu hg u2014 xe lamp with a 365 nm reflector and a power of 40 milliwatts per square centimeter mw cm 2 the polymerisable composition was applied to a substrate in this example a kbr pellet in the form of a single layer with a thickness of 20 micrometers u03bcm the maximum rates of polymerisation rp as well as the conversions x after 400 seconds.