Phase diagram, PMMA

In the previous section we have described the three types of phase behavior observed in the low-molecular-weight PMMA/PS system and reviewed the four types observed in the low-molecular-weight PS/PMMA system. These various phase relationships have been studied in terms of their dependence on the molecular weight (Mn) and weight percent (W) of the initial polymer present. Further, we have presented quantitative data concerning the sizes of the dispersed particles, again correlated to variations in Mn and W. In this section we will discuss the results in terms of the poly (methyl methacrylate )/polystyrene/styrene and poly-styrene/poly( methyl methacrylate)/methyl methacrylate ternary phase diagrams, whichever is appropriate. 

Although probably similar in general form, the PMMA/PS/S phase diagram discussed here is not a mirror-image of the low-molecular-weight PS/PMMA/MMA phase diagram which we have described in an earlier report (18). There are at least two indications of this, namely as follows. 

Figure 21. PMMA/PS/S phase diagram with three reaction lines indicating reaction line 1, one phase system (type (1)) reaction line 2, PMMA dispersed in PS (type (2)) and reaction line 3, PS dispersed in PMMA (type (3))...

Figure 22. PMMA/PS/S phase diagram with two reaction lines indicating possible final phase relationships...

Dispersed Particle Size. We will continue now to consider the variations of the dispersed particle size, S, with W and Mn, and their relationship to the PMMA/PS/S phase diagram. The experimental values of S reported in Table II are shown graphically in Figure 23 where, in all... 

Figure 26. PMMA/PS/S phase diagram indicating various relationships between molecular weight and composition of PMMA and the dispersed particle size...

Chu et al. [96] heated PS/PVME above 139°C for 30 min and quenched it at 0°C. Tip relaxation values of component polymers were observed through well-resolved peaks. By comparing these values to Tip of non-heated blends at various composition determined experimentally, they estimated the coexistent compositions at various heat-treatment temperatures and a LCST phase diagram was obtained. Asano et al. analyzed relaxation curves of PC/PMMA [92] and PS/PVME [52] by using Equation (10.9). 

Ti values of PC and PMMA in PC/PMMA = 50/50 agree well to show its miscibility on a scale of —20 nm. They observed relaxation curves after heat treatment for 30 min at various temperatures. When heated above 150°C, the relaxation curve becomes nonsingle exponential, and they attributed this temperature of 150°C to the phase-separation temperature of PC/PMMA = 50/50. The relaxation curves were fitted to Equation (10.9) to deduce the coexistent compositions at various temperatures to give a LCST phase diagram. They further studied kinetics of phase separation, which will be discussed in the following. 

PMMA/Phenoxy Phase diagram determined using turbidity measurements. LCST = 158°C and 30 wt% Phenoxy. Chiou Paul, 1991 Etxeberria et al., 1997... 

DCS at 20°C/min. Diverse phase diagrams Samples prepared by casting from CHClj DSC measurements at 20°C/min T < 530K T taken at half-height Samples cast from DMF into Petri dish DSC at 20°C/min to 190°C. Miscibility only for the GMA < 35.7 wt% in PMMA-GMA Samples hot cast from o-dichlorobenzene into Petri dish DSC at 20°C. Samples annealed at 200°C for 5 min THF solution precipitated by MeOH. DSC at 10°C/min T taken as mid-point in the inflection Samples either cast, precipitated from solution, or melt mixed at 250°C. DSC at 20°C/min T from second scan. Solution cast samples gave two T, whereas the other methods only one Melt mixing at 300°C. DSC at 20°C/min. T taken at onset... 

Figure 6.3. The metastable phase diagram for the polyure-thane-poly(methyl methacrylate) SIN at 60°C. The PMMA gels at and above the plane Gj- U -PU. The intersection of the PMMA gelation plane and the surface along the curve A represents the condition of simultaneous phase separation and PMMA gelation.

Figure 6.4. The metastable phase diagram, same compositions as Figure 6.3, illustrating the PU gelation plane, G2-MMA-PMMA.

Figure 8.17. Phase diagram of PVDF/PMMA system and the structure formation. The virtual UCST phase boundary is drawn, basing on the kinetic analyses, liquid-liquid phase transition, and crystallization as detected by light scattering [Tomura et al., 1992], Pictures (a) and (b) are for 60/40 PVDF/PMMA blends crystallized above UCST (150°C) and below UCST (110°C), respectively [Saito et al., 1987],...

The experimental setup of the ellipsometry provides directly temperature dependent data of the interfacial thickness X, which can be used to calculate the polymer-polymer interaction parameter Xab as a function of temperature The temperature dependence in the system PS/PMMA can independently be confirmed by measuring phase diagrams of oligomers and their PVT data. Having these data, it is possible to calculate XAh(T) by using the Flory- Huggins theory or an equation-of-state (EOS) theory. 

Here ct,2 and XerSre the composition and the interaction parameter at the critical point. Having a number of critical data it is possible to obtain the temperature dependence of Xs/mma because at the critical point Xs/mma = Xc Critical data were also obtained for the blend systems PS-1.39K/PMMA-6.35K and PS-1.39K/PMMA-12K. Figure 11 shows the temperature dependence of Xs/mma obtained by phase diagrams and applying the FH theory. Furthermore, a number of literature data and the temperature dependence of Xs/mma calculated with Flory s EOS theory can be seen and will be discussed below. Using Flory s EOS the interaction parameter X12 is ... 

Figure 10. Phase diagram of PS-1.2SK / PMMA-6.3SK. (x) - cloud samples, (°) transparent samples,...

PMMA/Phenoxy LCST = 158 °C (30 wt% phenoxy). Phase diagram from turbidity Chiou and Paul 1991 Etxeberria et al. 1997... 

Poly(a-MSAN)/SAN, TMPC, PVC, PPE or PMMA PMMA-GMA/SAN or TMPC Samples either cast from THF, or hot cast from DMF or acetonitrile, dried at 150 °C for 2 days DSC at 20 °C/min. Diverse phase diagrams 10... 

As shown in Fig. 6.3, Mishra et al. (1995) presented a tetrahedron as the spatial form of their metastable phase diagram, the comers of which represented MMA, PMMA, urethane prepolymer U , and PU. The PMMA contained 0.5 % tetraethylene glycol dimethacrylate, causing it to gel after about 8 % conversion see the Gi- U -PU plane. The phase separation curve for the ternary system MMA-PMMA- U (front triangle) on polymerization of only the MMA is indicated by the points C-D-A-E. Similarly, the phase separation curve for the MMA-PMMA-PU system (see rear triangle. Fig. 6.3) is represented by the points J-B-K-L. Thus, the entire tetrahedron volume is divided into two regions one phase separated and the other single phased, separated by the curvilinear constmction C-D-A-E-L-B-J. This surface exhibits a characteristic sail-like shape. 

Fig. 7.21 The equilibrium phase diagram of PSAN/ PMMA under shear flow at several shear rates. Symbols represent the cloud point data of the system PSAN/PMMA in the quiescent (Berrayah and Maschke 2011)...

The effect of a simple shear flow on the phase behavior and morphology was investigated with the use of a parallel-plate apparatus (Fig. 8.4, Madbouly et al. 1999a) for some polymer mixtures poly(methyl methacrylate) (PMMA)/ poly(styrene-co-acrylonitrile) (SAN-29.5) and polystyrene (PS)/poly(vinyl methyl ether) (PVME), which have an LCST-type phase diagram PS/PMMA, which has a UCST-type phase diagram and polycarbonate (PC)/SAN and nylon4, 6(PA4,6)/ poly(phenylene sulfide) (PPS), which are immiscible in the whole measurable region under the quiescent state. 

Fig. 8.6 Phase diagrams at various shear rates of PMMA/SAN blend. Phase diagram does not change more than y = 12 s ...

Fig. 8.29 Triangle phase diagram of st5Tene/PMMA/ PS system at 80 °C. Spinodal and binodal curves are by broken and solid lines, respectively. Arrow indicates the polymerization process...

---