Modification using interpenetrating

In this regard, preferential use of NIPU in hybrid systems based on copolymerization and modification of other polymer materials seems promising. Using an interpenetrating polymer network (IPN) principle in production of composite materials provides a unique possibility to regulate their both micro- and nanostructures and properties. By changing the IPN formation conditions (sequence of polymerization processes, ratio of components, temperature, pressure, catalyst content, introduction of filler, ionic group, etc.), it is possible to obtain a material with desirable properties. 

Even in the phase separated blends, where some degree of partial miscibility or compatibility exists between the components, simple melt blending in an intensive shear mixer is adequate for making a well dispersed, reasonably stable blend product with useful combination of properties, such as polypropylene/ethylene-propyl-ene rubber blend, ABS/polycarbonate blend, etc. The self-compatibUizing nature of these blends stems from partial miscibility and the mutual interpenetration of polymer chains at the interface. Slight modifications of the polymer backbone are often employed, particularly in the case of styrenic and ABS resins to induce partial miscibility with other resins. 

The second growing trend is the impact modification of polyolefin blends using styrenic block copolymers, which are known to be clear, strong, have low glass transition, compatible with PP, form interpenetrating polymer networks, and very efficient in contrast to maleic anhydride-grafted polyolefins. 

Phenolics can be chemically modified during synthesis by the use of substituted monomers or monomer mixtures. After synthesis additional modification can occur by electrophilic ring substitution, nucleophilic hydro l group capping, and reactions with compounds of boron, phosf orous, silicon, and titanium. Furthermore, phenolics can be physical modified by formation of polymer blends, interpenetrating polymer networks, and foam or by using fibers, fillers or other additives. 

As stated in Chapter 1, modification of existing commercial polymers by physical and chemical means is one of most widely used industrial techniques for improving the properties of base polymers without the need to develop new polymers. Like other resins, polyesters may also be modified by functionalisation, copolymerisation, blending, interpenetrating network formation, and so on. The properties of oil-modified polyesters may be improved by appropriate modification with a variety of reactive chemicals and other polymeric materials. 

Interpenetrating networks. These are composite materials that are often used in polymer technology to circumvent the frequently encountered problem that modifications that enhance a desired performance parameter (e.g. conductivity) often do so at the expense of mechanical properties. One polymer network system provides the matrix for the required process and mechanical stability is conferred by the other. 

ABS). This material has excellent performance and a relatively low price and is widely used in many fields. In addition, two kinds of polymers in the interpenetrating polymer network (IPN) interpenetrate each other and form a continuous network structure of two phases, as in the chemical modification method. The application of IPN is not yet universal. However, it is expected that it will be adopted. 

In general, naturally occurring polymers do not exhibit thermal responsiveness. Various strategies were envisioned to confer this physicochemical property to polysaccharides, such as chemical modification or formation of interpenetrated networks with other thermoresponsive polymers. Most of the published works report the use of thermoresponsive hydrogels based on PNlPAAm (Rzaev et a/., 2007). Examples of copolymers which may be grafted with PN IPAAm are chitosan (Martins e/ /., 2011), de xtran (Huang and Lowe, 2005 Huh et al, 2000), gelatin (Ohya and Matsuda, 2005), or... 

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