POLYMER PROPERTIES INFLUENCING CURL RETENTION 873 øo 20 40 60 HYDROPHOBIC MONOMER, MOLE (%) 8O Figure 12. Equilibrium moisture content at 90% RH for carboxylated vinyl acetate ter- polymers with increasing amounts of hydrophobic toohomer (22øC) Figure 13. 50' x 40' '" 50 • 20 (,.) o o io 0- o t• 2'0 3'0 ,• 5'0 6• ?• HYDROPHOBIC MONOMER, MOLE(%) Molecular weight as a function of carboxylated vinyl acetate terpolymer COlll- position hydrophobic monomer. The relationship of equilibrium moisture content rs. neutralization for Polymers A and B (Fig. 8) indicates the same relative improvement observed with curl retention. The incorporation of a hydrophobic moiety in the polymer structure enhances the curl retention at high humidities and decreases the equilib- rium moisture content of the polymer. It is apparent that this relation- ship holds true over the complete neutralization range of the carboxyls in the polymer structure. It was also found that the moisture vapor transmission rate (MVTR) of the carboxylated polymers increases with increasing neutralization (Fig. 9). This latter relationship shows that, notwithstanding the inclusion of a hydrophobic moiety into the

874 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 14. 20 18 16 I0 •. 6, 0•) I0 20 •0 40 50 60 70 HYDROPHOBIC MONOMER, MOLE(%) Moisture transmission relative to increased hydrophobic monomer incorporated into carboxylated vinyl acetate terpolymers (22øC) Figure 15. 20. 00 10 20 30 40 5• MOLECULAR WEIGHT X J0 -3 Moisture transmission as a function of the molecular weights of the polymers illustrated in Fig. 14 (22øC) • 70 I- 60 o o I0 20 30 40 50 MOLECULAR WEIGNT XlO-3 Figure 16. Curl retention at 90% RH as a function of molecular weight for a series of car- boxylated vinyl acetate terpolymers. Upper curve, 40% neutralization with AMPD Lower curve, 100% neutralization with AMPD, 0.06 g deposited and 30 minutes exposure (22øC)