POLYMER DEPOSITION IN HAIR 549 lOO • 60 I E I •o so• 40• I •ol , , , o 20% i.o% 2.5% Figure 3. 10 20 30 40 50 60 Time, minutes Effect of time and monomer concentration on the rate of polymer deposition in hair To determine the energy of activation for the deposition process, polymerization experiments were carried out at four different tempera- tures. It is seen from the results in Table XII that the temperature has little effect on the deposition accordingly, the energy of activation cal- culated from the initial slopes in Table XII gave a value of only 5.6 kcal. Table XIII lists some of the results of experiments which at all stages (pretreatment and polymerization) were carried out at a liquor:hair ratio = 5: 1. Evidently, satisfactory deposition of polymer can be realized under these conditions.

55O JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table XII Effect of Temperature on Polymerization of Methacrylamide in THPC-treated Hair in 0.01N H2SO4 at Liquor:Hair Ratio 50:1 [MAM] = 50 gl-• [K2S•O8] = 3 gl -• Temp o C Polymer Deposit after 10 rain 20 rain 30 min 45 min 60 rain Initial Slope S ( % increase in weight per rain) 25 21.1 • ... 35.7 43.7 49.8 1.40 30 24.0 • ... 41.8 49.8 55.2 1.60 35 19.5 33.4 43.1 ... 56.0 1.95 40 22.8 36.0 45.4 ... 59.5 2.28 After 15 min. Table XIII Polymerization of Methacrylamide in THPC-treated Hair at 25øC lPretreatment Polymerization Deposit (30 min) (30 rain) (%) 0.2M THPC at pH 5.2 and 40øC 0.2M THPC at pH 5.2 and 40øC 0.23//THPC at pH 5.2 and 40øC 0.2M THPC at pH 5.2 and 40øC 0.2M THPC at pH 5.2 and 25øC 0.2M THPC at pH 5.2 and 25øC 0.1M THP in H20 at 25øC In 0.01N H•804, IMAM] = 200 g1-1 28.1 [K2S•O8] = 3 gl -• In 0.01N H•SO4, IMAM] = 200 g1-1 32.8 [K•S•Os] = 6 g1-1 In 0.01N H•SO4, IMAM] -- 200 gl -x 31.0 [K•S•O8] = 12 g1-1 In H20, IMAM] = 200 gl-1 26.7 [K•S•Os] = 6 g1-1 In H,, IMAM] = 200 gl -• 24.0 [K,,Os] = 6 gl -• In 0.01N H2804, IMAM] = 200 gl -• 26.5 [K,,s] = 6 gl -• In 0.01N H,O4, IMAM] = 200 gl -• 46.0 [K,208] = 6 gl -• •DISCUSSION The method of polymer formation in hair described above is in many ways similar to the wool/persulfate system examined earlier (3, 8) however, a different mechanism of initiation may be operative under some of the conditions used. In the wool/persulfate system, the rate of initiation is clearly a function of the absorption of persulfate by the fiber as the latter depends critically on pH, high polymer deposits are obtained at low values of pH while almost none are realized in experiments carried out at pH 6.