usually by means of radical type polymerization initiators such as organic peroxides where the reaction initiation temperature is appropriate for the temperature of said well or line examples 1 to 6 and the tests employed will now be described with the aim of demonstrating the principal advantages and properties provided by the choice of formulations used to produce the flexible preforms of the present invention with reference to the use of an epoxy resin to form identical flexible preforms with the exception of the resin used these tests were carried out with the resins and hardeners shown below commercially available vinyl ester resin in accordance with the invention 100 g of ebecryl u00ae 616 resin from ucb epoxydimethacrylate oligomer diluted with 25 3 pwhr of bc 500 inhibitor from scpo was added to 100 g of rtc 144222 12 resin an experimental resin based on bisphenol a methacrylate from dow deutschland inc in solution in ebecryl u00ae 150 from ucb epoxy resin known and described in the prior art in european patent application no 833 036 comparison 41 3 g of m dea amine 4 4 methylene bis 2 6 diethylaniline lonzacure u00ae from lonza ltd was added to 100 g of dgeba diglycidyl ether of bisphenol a ly556 epoxy resin from ciba formulations 1 and 2 were then polymerized for 2 hours at 120 u00b0 c and formulation 3 was polymerized for 8 hours at 140 u00b0 c the test carried out in this example consisted of determining the behavior and strength of hnbr rubber hydrogenated nitrile rubber in the presence of reactive solvents used in the unsaturated resin composition this example illustrates the.