Compatible polymer blends, definition

Sometimes, in analogous to metal alloys, the term polymer alloy is used. According to the lUPAC recommendation, the term polymer alloy for a polymer blend is discouraged. The term polymer alloy should be used for polymeric materials with macroscopically uniform physical properties in their whole volume. This definition includes compatible polymer blends, miscible polymer blends, or multiphase copolymers. 

Compatibility in the polymer blends is defined by either miscibility on the molecular scale or absence of gross symptoms of phase separation. This definition is phenomenological and empirical but no unanimous theoretical scheme for predicting compatibility has been established. Thermodynamics predicts that exothermic mixtures satisfying Equation 5 would spontaneously mix,... 

Compatibility. Clear definition of compatibility is rather difficult. Compatibility has been defined as the ability of two or more materials to exist in close and permanent association for an indefinite period without phase separation and without adverse effect of one on the other [28]. On the other hand, compatibility is easily recognized in solvent-borne adhesives as a homogeneous blend of materials without phase separation. Normally, compatibility is understood as a clear transparent mixture of a resin with a given polymer. But, compatibility is a more complex thermodynamic phenomenon which can be evaluated from specific... 

The definition of compatibility has been differentiated from miscibility since it is concerned with phase-separated polymers and is approached through the attainment of optimum properties for the blend (Bonner and Hope, 1993). Two of the main technologies used to achieve it are the addition of a third component (as discussed above) and reactive blending. The target in using a compatibilizer is the control of the interfacial tension between the components in the melt, translating to interfacial adhesion in the blend after processing. 

While detailed descriptions of relevant terms are placed as appropriate throughout the text, brief definitions are in order at the outset. After blending together, polymer pairs may be qualitatively considered incompatible, semicompatible, or compatible, depending on whether two distinct or immiscible phases remain, partial mixing of the two polymers takes place... 

Very similar polymeric materials, that is, polymers with similar chemical constitutions, and, therefore, relatively good compatibility, form fine morphologies. Figure 1.11 shows the morphology of a blend of 80% HOPE with 20% of a highly branched PE (VLDPE) with small spherical particles about a few hundreds of nanometers large that are well distributed in the HOPE matrix, which has a definite lamellar arrangement (see also Fig. 4.61(a), (b)). 

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