POLYMER PROPERTIES INFLUENCING CURL RETENTION 871 2 o• • POLYMER "A" i-: 10 m Z • 'MER" B" OL'Y o 6 cr 5 m_ 4 o •2 o i 0 20 40 60 80 100 NEUTRALIZATION {%) Figure 8. Equilibrium moisture content at 90% RH for Polymer A and Polymer B vs. neutralization with AMPD (22 øC) 4.0 3.6 5.2 2.8' POLYMER"B"POLYMER NEUTRALIZATION (%) Figure 9. Moisture vapor transmission rate (MVTR) at 90% RH vs. neutralization with AMPD for Polymer A and Polymer B (22øC) The mean curl retention of Polymer B varied as the neutralization and deposition weight was altered (Fig. 5). It can be seen that both neutralization and deposition weight have an effect on curl retention. Increasing neutralization tends to decrease curl holding ability in- creasing polymer deposition on the hair offers a significant increase in retention. An alternate method of illustrating the data is shown in Figs. 6a and 6b. A system of iso-retention lines was constructed so

872 Figure 10. JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 16 12 1 4 POLYMER "A"•,•,.••• 2 0 0 I0 20 30 40 50 60 70 80 NEUTRALIZATION (%) Sward Rocker hardness at 90% RH vs. neutralization with AMPD for Polymers A and B (22øC) 80. _o 70 z ,.,- 60 o 50, z 4½ 0 20 40 60 HYDROPHOBIC MONOMER (MOLE%) Figure 11. Curl retention at 90% RH for carboxylated vinyl acetate terpolymers containing increasing amounts of hydrophobic •nonomer. Neutralized 40% with AMPD at 30 minutes exposure (22øC) that the three coordinates--deposition weight, neutalization, and ex- posure time--might be visualized. Each system of lines might be considered a plane or slice removed from the three-dimensional surface generated by the three coordinates. The relationship demonstrated with the iso-retention lines might be clarified with one specific example. From Fig. 6a, it can be seen that at a deposition of 0.06 g of resin (50% neutralized), the mean retention was 75%. By extrapolation, a deposition weight of 0.075 g (75% neutralized) will also result in 75% retention. A comparison of Polymer A and Polymer B (Fig. 7) demonstrates the improved high-humidity curl retention achieved by including the