Polymer blends and IPN

An IPN has different properties from either a copolymer or a polymer blend. It may swell in solvents, but will not dissolve it will resist creep or flow to a greater extent than copolymers or blends. Some differences in the physical properties of IPNs compared with polymer blends can be seen in Table 10.3. The major reason for the differences in properties between polymer blends and IPNs is that the latter have greater adhesion and better mixing. 

Dual Phase Continuity. Dual phase continuity has been shown to be important in numerous polymer blends and IPN s, to achieve special properties. Dual phase continuity is defined as a region of space where two phases maintain some degree of continuity. An example of dual phase continuity is an air filter and the air that flows through it. A Maxwell demon could traverse all space within the air filter phase, as well as within the air phase. 

Hydrogels and amphiphilic membranes Poly(carbophosphazenes) and poly(thiophosphazenes) New condensation syntheses NLO and high refractive index polymers Microencapsulation of mammalian cells (PCPP) Polyphosphazene polymer blends and IPN s Borazine derivatives Poly(phosphazophosphazenes)... 

Thermoplastic IPN. When physical crosslinks rather than chemical crosslinks are utilized, the materials may flow at elevated temperatures. As such, they are hybrids between polymer blends and IPNs. Such crosslinks commonly involve block copolymers, ionomers, and/or semicrystallinity. 

Amongst the above mentioned compatibilization methods, the obtaining of IPNs and SIPNs often proved to be a promising and very efficient route. An IPN is a polymer alloy comprised of two or more chemically crosslinked polymers. The difference between polymer blends and IPNs is that the latter ones swell instead of dissolving in solvents and do not creep or flow. Types of IPNs include sequential, simultaneous, latex and gradient IPNs and may also be thermoplastic (i.e. when physical crosslinks are imphed). Thermoplastic IPNs behave as thermosets at ambient temperature, but usually flow when heated at certain temperatures, possess IPN properties and often exhibit dual phase behavior [1]. 

J. A. Faucher and M. R. Rosen, Shaped Article for Conditioning Hair, a Blend of Water-Soluble and Water-Insoluble Polymers with Interpenetrating Networks, U.S. Pat. 4,018,729 (1977). Polymer blend, hair conditioning combs of (polycaprolactone blend, hair conditioning combs. Hair preparations, conditioners water insoluble/water soluble polymer blends and IPN-related materials. Combs and shaped articles. 

K. Kircher, Kombinationswerkstoffe aus Polyurethan und Vinyl-polymeren, Angew. Mak-romol. Chem. 76/77, 241 (1979). Polymer blends and IPNs based on polyurethanes and poly(methyl methacrylate). SINs. Electron microscopy and mechanical behavior. Impact-resistant plastics. 

D. A. Thomas, Morphology Characterization of Multiphase Polymers by Electron Microscopy, J. Polym. Sci. Polym. Symp. 60, 189 (1977). Morphology of polymer blends and IPNs. Electron microscopy techniques. 

Polymer Blend and IPN Classification Scheme. Of course, all of the various compositions of matter composed of two polymers are related to each other. Figure 3 (19) illustrates how the major kinds of poljnneric materials based on two kinds of mers are related to each other. The IPNs are shown here imder the occasional grafts heading, because many of the preparations have a few grafts between the two pol5uners as a consequence of free-radical chemistry, etc. Since one network of these materials is always polymerized in the presence of the other... 

Fig. 17. Phase continuity and inversion diagram for polymer blends and IPNs during polymerization and under shear.

The transport of liquids, vapours, and gases though polymer blends and IPN s is of fundamental importance to a polymer scientist. The driving force behind the transport process is the concentration difference between the two polymer phases or the chemical potential of the penetrant in the phases separated by the membrane. The transport process involves the sorption, diffusion, and permeation of the penetrant into the polymer system. 

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