means materials and embodiments it is to be understood that the invention is not limited to the particulars disclosed and extends to all equivalents within the scope of the appended claims in the following examples all parts and percentages are by weight unless otherwise indicated a polyvinylamine solution hercobond u00ae 6363 dry strength resin 1000 g 12 active solids available from hercules incorporated was added to a 2 l reaction flask and was adjusted to ph 11 3 11 5 using 50 naoh acrylamide solution 160 g 50 was added dropwise at room temperature for 20 minutes while the temperature of the reactants gradually increased to 40 45 u00b0 c the resulting mixture was stirred at 70 u00b0 c for 5 hours and the ph of the reaction mixture was maintained at 11 0 11 5 using 50 naoh the reaction mixture was then cooled down to 25 30 u00b0 c and the ph was adjusted to 8 0 9 0 using a concentrated hcl to the resulting solution was added sodium metabisulfite 1 g the mixture was stirred for 10 minutes at room temperature the resultant product had 15 2 solids ph 8 5 460 cps brookfield viscosity the residual acrylamide was not detected by a standard liquid chromatographic method specifically designed for monomer analysis the charge density of the polymer was measured to be 4 7 meq g ph 7 0 the structure was confirmed with 1 h and 13 c nmr analysis and the molar ratio of vinylamine units to the added acrylamide was determined to be 60 to 40 based on the integration of 1 h.