Abstract: The invention relates to a process for preparing products containing polymer chains in which a linear prepolymer or polymer contains at least one free acid group at each chain and is reacted with an alkoxide of a metal having a valence of more than 2, such as zirconium, titanium or cerium, possibly in the presence of a non polar solvent, the alkoxide of the metal having a valence of more than 2 being used in such a quantity that the alkoxide functions are in excess with respect to the stoichiometric amount of the acid functions carried by said linear prepolymer or polymer, the reaction mixture being stirred in the presence of humidity until a product is obtained wherein the hydrogen atoms of the free acid end groups of the prepolymer or polymer are substituted by an atom of the metal (M) which is itself linked to another atom of said metal by M-O-M linkages. The invention relates also to the products containing a prepolymer or polymer .alpha.,.omega.

Abstract: Viscous, homogeneous and thermoreversible gels containing polymer chains are obtained by a process in which a solution of a prepolymer or polymer which contains at least one free acid group at each chain end in a non polar solvent selected among the aliphatic, alicyclic and aromatic hydrocarbons having a dielectric constant of less than about 3 is reacted at room temperature with a stoechiometric amount, based on the acid group content of the polymer, of a metal aliphatic alkoxide so as to neutralize all the free acid groups and a sufficient amount of the non polar solvent is distilled for removing, in a substantially quantitative manner, the aliphatic alcohol formed by said reaction.

Abstract: A well casing perforator adapted to be used with pneumatically powered rotary drilling equipment. It includes an upright elongated body which is inserted within the casing. The body is attached to the lower end of a drill rod which imparts vertical or angular movement to the elongated body while within the casing. The body is guided axially within the casing by rollers which engage the interior casing wall. A rotatable wheel has teeth capable of penetrating the casing wall as the wheel rolls in engagement with the casing. The wheel is mounted at the outer end of a carrier pivoted to the elongated body about a horizontal axis. The carrier in turn is controlled by a piston assembly subject to pneumatic pressure within the drill rod. The piston assembly is pivotally connected to the carrier to move it from a first position at which the wheel is retracted from engagement with the casing to a second position at which the wheel engages the interior wall of the casing.