Synthesis of Vinyl Polymer‐Starch Composites to Serve as Size Base Materials

Abstract

AbstractStarch was polymerized independently with acrylamide, acrylic acid, methacrylic acid and acrylonitrile (AN) using potassium persulphate (K2S2O8) as initiator. The products of the polymerization reaction consisted of free starch, grafted starch, homopolymer and oxidized starch. The ratios of these composite constituents were found to differ considerably depending upon the nature of monomer as evidenced by differences in viscosity curves (amylograph‐viscograph) as well as sizeability of the composites and their ease of removal from cotton yarns during desizing. Also studied was the dependence of the extent of polymerization (grafting and homopolymerization) of AN to starch on K2S2O8 and AN concentrations, polymerization temperature, starch/AN ratio and starch + AN/liquor ratio; and the onset of these factors on the apparent viscosity of the composite obtained thereof. Results indicated that the extent of polymerisation increased by increasing the persulphate concentration to 6 g K2S2O8/100 g starch then levelled off; the same held good for apparent viscosity but the latter decreased upon using concentrations higher than 6 g K2S2O8/100 g starch. While the extent of polymerization increased over a range of 8‐32g AN/100 g starch, apparent viscosity decreased. Raising the polymerization temperature from 30 to 60°C caused significant enhancement in the extent of polymerization but with the certainty that maximum apparent viscosity was attained at 50°C. The extent of polymerization was much favoured at higher AN ratio, but maximum apparent viscosity was attained at starch/AN ratio of 83:17. On the other hand, the extent of polymerization decreased by increasing starch + AN/liquor ratio upto 1:75 then remained almost constant upto a ratio of 1:12.5; meanwhile maximum apparent viscosity was observed at a material/liquor ratio of 1:7.5. The results were interpreted in terms of differences in the magnitude of constituents of the poly (AN) ‐ starch composite and their affinity for and swellability in water.