Biodegradable anionic polymers are disclosed which include recurring polymeric subunits preferably made up of vinylic and dicarboxylic monomers such as vinyl acetate or vinyl alcohol and maleic anhydride, itaconic anhydride or citraconic anhydride, or combinations thereof. Carbon-carbon composites formed from porous preforms in which pyrolysis oil comprising a phenolic compound and at least one of an aldehyde or ketone compound is disposed in pores of the preform are also described. The data path is subdivided into n successive sections, each of which contains, at its input, a clock-controlled sampling element for accepting the data to be transmitted and has a propagation time that is considerably shorter than Tmin.