High-pressure calorimetric study of plasticization of poly(methyl methacrylate) by methane, ethylene, and carbon dioxide

Abstract

Glass transition in the system poly(methyl methacrylate)/compressed gas was studied as a function of the gas pressure p using a high‐pressure Tian‐Calvet heat flow calorimeter. Measurements were made on PMMA‐CH4‐C2H4, and ;‐CO2 at pressures to 200 atm. All three gases plasticize the polymer leading to depression of the glass transition temperature Tg. Trends in the Tg depression were the same as those reported for the solubility of these gases in PMMA; the higher the solubility the larger the depression in Tg. CO2 was found to be the most effective plasticizer producing a depression of about 40°C at a pressure of about 37 atm. In the low‐pressure limit, the pressure coefficient of the glass transition temperature (dTg/dp) was found to be about −0.2°C atm‐1 for PMMA‐CH4, the same as that observed for polystyrene‐CH4. For PMMA‐C2H4, the pressure coefficient was −0.7°C atm‐1, which is lower than the value of −0.9°C atm‐1 observed for PS‐C2H4. The pressure coefficient for PMMA‐CO2 was found to be about −1.2°C atm‐1, which is larger than the value of −0.9°C atm‐1 observed for PS‐CO2. © 1996 John Wiley & Sons, Inc.

Simultaneous determination of sorption, heat of sorption, diffusion coefficient and glass transition depression in polymer–CO2 systems

“…Solubility, diffusion coefficient, and swelling data are the most studied or some combination of them [9,[14][15][16][17][18][19][20][21][22][23]. Less abundant are studies about polymer plasticization induced by gas sorption, the majority of which are based on scanning calorimetry with rather poor results especially in systems that exhibit retrograde vitrification [20,[24][25][26][27]. Very rarely are reported experimental data on heat of sorption in polymer-gas systems [28].…”

Effect of Compressed CO2 on Phase Transitions and Polymorphism in Syndiotactic Polystyrene

“…The results shown in Figures 6 and 7 are in agreement with previous studies 20,31,41 which showed that on annealing sPS in the range 120-220°C, the planar mesophase is nucleated first, which then converts into the poorly ordered R′ form. The extent of conversion depends on the annealing temperature and time.…”

“…On saturation with CO 2 , both the glass transition and the crystallization events move to lower temperatures, and the glass transition becomes sluggish. The plasticization effect of CO 2 on sPS is similar to those observed in other polymer-CO 2 systems, [28][29][30][31]39 whereas the depression in crystallization temperature is similar to that reported for poly(p-phenylene sulfide)-CO 2 . 35 The depressions in T g and the cold crystallization temperature T c for sPS-CO 2 are plotted against the CO 2 pressure p in Figure 3.…”

Crystallization Condition of Glassy Syndiotactic Polystyrene in Supercritical CO2

“…9 According to the result by Handa et al, the crystallization temperature decreased with increasing pressure of CO 2 . [18][19][20] This effect is explained by plasticization due to CO 2 dissolved in the film. The glass transition temperature (T g ) is depressed and therefore the crystallization occurs at lower temperature.…”