Problem 2: Suppose that we need to process a grade of Poly(methyl methacrylate), PMMA by injection molding. The PVT data of PMMA are shown in Figures 1 and 2.
Figure 1 shows the isobaric volume measurements at atmospheric pressure of PMMA upon cooling from 235°C to 30°C. The experiment was performed at a cooling rate of 100 C°/min.
Figure 2 shows the isothermal volume measurements at 235°C of PMMA upon pressurization from 0.1 MPa to 220 MPa. The pressurization rate is 25 MPa/sec.
a) Calculate the glassy and liquid thermal expansion coefficients ($\alpha_g$ and $\alpha_l$) of the PMMA sample. Plot $\alpha$ as a function of temperature and calculate $\Delta\alpha$.
b) Calculate the glassy and liquid compressibility coefficients ($\beta_g$ and $\beta_l$) of the PMMA sample. Plot $\beta$ as a function of pressure and calculate $\Delta\beta$.
c) Calculate the glassy and liquid bulk moduli, $K_g$ and $K_l$, of the PMMA sample. Plot K as a function of pressure and calculate $\Delta K$.
4) Estimate the change in $T_g$ of the PMMA sample after an increase in hydrostatic pressure, at 235°C, from 0.1 MPa to 110 MPa. Justify your answer.
