VINYL COPOLYMER IN THE COSMETIC COSMOS 299 WA"ER ABSOiIPTION V,• . TIME FCR VINYL :OPOLYMEF (UNNEUT•ALIZED) ,• ANI 90%NEI TRALIZED AND PVP AT 50% •H /•...-.- -- 0 IPVP T VINY COPOLYI•IER (90% NEUTRALIZED) _ () ( VIN'YL COPOLYI4ER (UNNE JTRALI•-•I•j -i'-- •, { ' 0 0 2 4 6 8 10 12 14 16 TIME IN HOURS ß Figure 11.--Moisture pick up rate at 50 per cent relative humidity for the 90 per cent neutralized resin rs. PVP. 6O 48 .• 24 WATER ABSORPTI DN VS. TII• E FOR VII•YL COPOLIfMER AT VARYIN, DEGREEI OF NEUTRALIZATION AND PVI AT 90%RH 125% N EU T.• ,,.•"'""• /•'• '• P V P // •- , % NEUT. ....... •NNEUT. 0 20 40 60 80 1DO 120 140 160 TIME IN HOURS Figure 12.--Moisture pick ups at 90 per cent relative humidit), of the vinyl copolymer at varying degrees of neutralization.

300 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 11 is a graph of moisture pick-up rate at 50 per cent relative humidity for the 90 per cent neutralized and unneutralized resin rs. PVP, another one of the few water and solvent soluble resins. Note that the rate of moisture pick up is approximately the same for the three materials. The lower levels of saturation of the vinyl copolymer are an indication of lower water sensitivity. The neutralization with AMPD, in addition to making the film more water soluble as shown in Fig. 10, also increases the moisture sensitivity. Figure 12 is a similar graph showing the moisture pick ups at 90 per cent relative humidity of the vinyl copolymer at varying degrees of neutraliza- tion. Note that increasing the degree of neutralization increases moisture sensitivity and that excess neutralization actually raises the moisture pick up above that of the PVP. The rate of moisture pick up for PVP is greater than the vinyl copolymer at 90 per cent R.H. Note too the higher levels of moisture pick up. At 50 per cent R.H. the 90 per cent neutralized resin picked up approximately 4 per cent moisture, while at 90 per cent R.H. the pickup was approximately 36 per cent. 48 4O • 16 S•fARD ROCKI--R HARDNI.'_SS VALUE, VS. % RI, OF VINYL COPOLYMi R (U•JNEUTRAL•ZED AND 90% NEU"RALIZED) AND PVP • • VIN'•L COPOL'• •IER 'dt• t, Et •R•,LiZED • •• PVP VINYL CO[OLY• )0 % NEUTRALIZED 10 20 30 40 50 60 70 80 % RELATIVE HUMIDITY Figure 13.--Comparative Sward rocker hardness for PVP and resyn 28-1310, on neutralized and 90 per cent neutralized, at varying humidities. Figure 13 is a graph showing comparative Sward Rocker Hardnesses for PVP, the unneutralized and 90 per cent neutralized resin at varying humid- ities. Note the relatively high value retained by the unneutralized resin.