POLYMERS BLENDS . e.Similar to the other raw materials . metals it is principally possible to vary the properties of macromolecular substances by mixing two or more different polymers .g. OBJECTIVES 1) To provide some design guidelines for the development of polymer blends 2 )To illustrate the commercial significance of polymer blends . Polymer blends immiscible Phase separatio n miscibl e Homogenous to the molecular . level no phase) . Miscibility depends on : 1) hydrophobic 2) hydrophilic 3) Electronegativity 4) polarity . polymers are immiscible unless there are strongly favorable enthalpic interactions Conditions for polymerpolymer miscibility Gmix H mix TS mix 0 .Polymers DON’T MIX . In general. we have to go back to the first law of thermodynamics . a rock on top of a mountain will roll down to the bottom of the mountain more easily than a rock on the bottom will roll to the top . This law says that when things change. To make that happen.Making Polymers Mix This presents a challenge to would-be polymer blenders . Think of it this way: if you'd like a physics example. they change from a state of more energy to a state of less energy. . Let me use an example to illustrate. we have to make them have less energy when mixed than they would be separate. Two polymers that do actually mix polystyrene + poly(phenylene oxide).What first law of thermodynamics have to do with blending polymers? in order to make two polymers mix. So they blend very nicely . aromatic rings like to stack up like little hexagonal poker chips.As you can see. As you may know. both of these polymers have aromatic rings.each other. these two polymers like to associate with . For this reason. . and you can mix .. At this glass transition temperatures point they will be nice and gooey. you'll be left with a blend at the bottom of your beaker. it could get expensive if you tried to do this industrially .When your material cools. presuming your two polymers are miscible . presuming your two polymers are miscible . So for making blends in large amounts. solvent. and then wait for the solvent to evaporate.again. you heat the two polymers together until you're above the of both polymers. When the solvent has all gone away. them together like a cake mix This is often done in machines such as extruders.While this method works fine in the laboratory.Making Your Own Blends Blends are usually made in two ways The first way is to dissolve two polymers in the same . you'll have a nice blend . For some polymer pairs that range gets smaller as temperature increases. Eventually. and those at which there is phase separation. . The graph on the right shows this. that range of immiscibility will become so small that it will disappear. The upside-down parabola is the boundary between those temperatures and compositions at which there is one phase.the composition range over which the two polymers phase-separate isn't constant. The temperature at which this happens is called the upper critical solution temperature or UCST. if you heat such a pair high enough. It can change with temperature. Thank you . GRAF. IKAWA. Y. M. 13... AND KWEI.20. TECHNOMIC. ED.. CHEM. J. . POLYM. K. PEARCE. E. P. 1984.. PEARCE. 4. ED. POLYM.. 1505. POLYM. E.. SCI... 1975. 1980. HONDA. P.. KWEI. B. 18. T. 1991. 3. M.2. J. 201... ET AL. SCI. COLEMAN. POLYM. SPECIFIC INTERACTIONS AND THE MISCIBILITY OF POLYMER BLENDS. SCI. AND TSUCHIDA. LETT.REFERENCES 1. TING. T.. M. AND PAINTER. E. AND MIN. J. ABE. CHEM. K. E.. M. F. K. P. J. MACROMOL. K. 1181. 21.. T. 4. Group names : Mohammad al-ajarmeh Mohammad al-atiyat Mohammad khalil Mohanad al-khzaala Mai abudayeh Maram abuajamiah . 5. 6. 1. 3. 2.