Miscibility immiscibility

Miscibility doors can be observed when the homopolymer A is miscible with the homopolymer consisting of segments of type 2. Usually, only very near to the miscibility-immiscibility boundary can a temperature dependence of the phase behavior be seen, i.e. an LCST occurs. Figure 5 shows examples for miscibility doors. Further systems are listed in Table 1. Miscibility doors were also observed for blends of styrene copolymers and polyfvinyl methyl ether) (PVME) (Fig. 6, Table 2). In contrast to PPO/PS systems blends of PVME and PS... 

Fig. 8. Miscibility window of 40/60 blends of poly(o-chlorostyrene-rcm-p-chlorostyrene) and PPG O miscible, immiscible [40]...

Fig. 17. The miscibility of chlorinated polyethylenes with others having a different chlorine content, (—) miscible (+) immiscible. Group C includes mixtures of rubbery polymers with glassy polymers and group D is generally mixtures of rubbery polymers with the largest differences in chlorine content. These two groups give the largest (unfavourable) equation-of-state contributions to the fiee energy of mixing...

Table 1. The miscibility of polymethacrylates with PVC when prepared by in situ polymerisation and by solvent casting, (+) miscible, (—) immiscible...

Thus, for miscible polymer blends, the relaxation spectrum is a linear function of the relaxation spectra of the components and their weight fractions, Wj, hence one may use rheological functions to detect miscibility/immiscibility of polymer blends. An example is presented in Figure 7.14 [Utracki and Schlund, 1987]. 

HOPE UHMWPE miscible/ immiscible dynamic Dumoulin et al., 1984... 

UHMWPE LLDPE miscible/ immiscible capillary Vadhar Kyu, 1987 Ree, 1987... 

LLDPE LLDPE miscible/ immiscible dynamic Utracki, 1985c Utracki Schlund, 1987b... 

Polymer blending is to combine two or more components and has superior mechanical, optical, or thermal properties than these individual polymers. From the practical and economical points of view, polymer blending from existing polymers is the most effective and convenient route to create new and useful materials with greater versatility and flexibility than the development of new polymers. Basically, three different types of blends can be distinguished completely miscible, immiscible, and partially miscible blends [1,2] as shown in Figure 2.1. 

It is common to distinguish between internal and external lubricants. The worst definition is based on who adds the lubricant if the supplier added it, it comes to the processor as an internal lubricant if the processor must add it himself, it is an external lubricant. A semimeaningful distinction an internal lubricant is compounded into the polymer an external lubricant is applied to the surface of the mold. The proper distinction is based on miscibility/immiscibility of the additive in the polymer an internal lubricant is miscible with the polymer and acts like a small amount of plasticizer to increase molecular flexibility and mobility, and to help the disentanglement and flow of tbe polymer molecules in the melt. An external lubricant is immiscible in the polymer and tends to exude to the surface of the plastic and form an abhesive (nonstick) interface between the polymer and the steel process equipment, or it tends to come to the surface of the finished plastic product and give it continual lubricity in the use of the product. 

Key Terms Solubility Miscible Immiscible Concentration of a solution... 

A new polymer modification process has been developed to reduce the cost of the engineering resin. The modification process is blended polymers. A blended polymer is a mixture of at least two polymers or a copolymer. There are three types of blended polymers miscible, immiscible, and compatible polymers. On occasion, blended polymers have properties that exceed those of either of the constituents. For instance, blends of polycarbonates (PC) resin and polyethylene terephthalate (PET) polyester were originally created to improve the chemical resistance of the PC. This is because PC actually had a fatigue resistance and low-temperature impact resistance that was superior to either of the individual polymers. 

The morphologies of the miscible, immiscible, and partially miscible polymer blends are distinct from each other. In an immiscible blend, two phases are present the discrete phase (domain), which is lower in concentration, and the continuous phase, which is higher in concentration. The miscible polymer blends exhibit singlephase morphology. Partially miscible polymer blends may form completely miscible blends at a different composition. The two phases may not have a well-dehned boundary. Each component of the blend penetrates the other phase at a molecular level. The molecular mixing that occurs at the interface of a partially miscible two-phase blend can stabilize the domains and improve the interfacial adhesion. A compatible blend that has commercial possibilities may be immiscible, and a miscible polymer blend may lack commercial applications due to other factors such as cost, source of raw materials, safety, and environmental issues such as recyclability. 

The solubility parameter values obtained from the simulations were found to be in reasonable agreement with those calculated using the traditional group contribution methods (Table 2.2). Furthermore, the miscibility/immiscibility prediction was experimentally confirmed, since DSC showed melting point depression of PEO with increasing levels of indomethacin and thermal analysis of blends of indomethacin with sucrose and glucose verified general immiscibility. The solubility parameter... 

Amorphous phase Miscible Miscible Miscible Immiscible ... 

---