Blending interpenetrating networks

The Commission on Macromolecular Nomenclature is currently working on the extension of macromolecular nomenclature to branched and cyclic macromolecules, micronetworks and polymer networks, and to assemblies held together by non-covalent bonds or forces, such as polymer blends, interpenetrating networks and polymer complexes. 

Many polymer materials contain polymer-polymer interfaces. These include polymer blends, interpenetrating networks, core-shell polymer colloids, and polymer micelles. The properties of these materials depend, one believes, on the nature of the interface and on factors which operate within very short distances (50A - lOOA) of the interface. These are the dimensions of polymer molecules, which means that a proper understanding of the performance of these materials requires understanding of the interface at the molecular level. 

Phenolics can be physically modified by blending, interpenetrating network formation, and the addition of fibers or fillers. The formation of multicomponent materials opens new directions for tuning of physical properties of polymers. 

Electroactive Nanoobjects and Nanostructures Related with Conducting Polymers Polymer Blends, Interpenetrated Networks and Related Electromechanical Devices Biological Applications and Bioelectrocatalysis... 

Polymer Blends, Interpenetrated Networks and Related Electromechanical Devices... 

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. 

Non-linear polymers comprise branched, graft, star, cyclic, and network macromolecules. Polymer blends, interpenetrating networks, and polymer-polymer complexes are summarized as macromolecular assemblies. Their skeletal structure should be reflected in the name by using an italicized connective as a prefix to the source-based name of the polymer component or components to which the prefix applies. Table 5.10.1 lists aU classifications for non-Unear macromolecules and macromolecular assemblies with their corresponding prefixes [971UP2]. Examples for nomenclature are given in Table 5.10.2 (non-linear macromolecules) and Table 5.10.3 (macromolecular assemblies). 

The component with the lower viscosity tends to encapsulate the more viscous (or more elastic) component (207) during mixing, because this reduces the rate of energy dissipation. Thus the viscosities may be used to offset the effect of the proportions of the components to control which phase is continuous (2,209). Frequently, there is an intermediate situation where a cocontinuous or interpenetrating network of phases can be generated by careflil control of composition, microrheology, and processing conditions. Rubbery thermoplastic blends have been produced by this route (212). 

SiHcone PSAs are blends or interpenetrating networks (IPNs) composed of a tackifyiag MQ resia cured ia a cross-linked poly(siloxane) aetwork. 

Another area of recent interest is covulcanization in block copolymers, thermoplastic rubbers, and elasto-plastic blends by developing an interpenetrating network (IPN). A classical example for IPN formation is in polyurethane elastomer blended acrylic copolymers [7]. 

Other methods of blending include (1) fine powder mixing, and (2) monomer as a solvent for other components of the blend, followed by polymerization for making an interpenetrating network (IPN) [15]. 

The classic objective of alloying and blending is to find two or more polymers whose mixture will have synergistic property improvements (Fig. 6-8). Among the techniques used to combine dissimilar polymers are cross-linking to form what are called interpenetrating networks (IPNs), and grafting, to improve the compatibility of the plastics. 

The information available on aqueous polymer blends is qualitative in nature because of the lack of a suitable theory to interpret the experimental observations. Mixed gels can be comprised of an interpenetrating network, a coupled network (as discussed above), or a phase-separated network [2]. The latter is the most common as the blends have a tendency to form two phases during gelation. In such cases the miscibility and thermodynamic stability have to be empirically investigated and proper conditions for miscible blends identified. This involves a phase diagram study as is described in [3]. 

The modulus of blends can be calculated by methods developed by Takayanagi, Nielsen and Kerner. Different values are obtained for interpenetrating networks and for particle-matrix morpholo-... 

So, the PVA/poly(sodium styrene sulphonate) [PSSNa] blend was obtained by casting aqueous solution of polymers mixture (PVA with Mw= 124,000-186,000 and HD=99% and PSSNa with Mw= 70,000). The resulted films were crosslinked with 1,2-dibromethane in gaseous phase. A semi-interpenetrating network (SIPN) in which polyelectrolyte (PSSNa) chains are trapped inside a based PVA network was obtained [44], A totally miscible blend with a very good film clarity and high mechanical resistance [44] resulted. 

D. Klempner and K. Frisch, eds., Polymer Alloys II Blends, Blocks, Grafts and Interpenetrating Networks, Plenum Press, New York (1980). 

Elastomer blends consisting of two immiscible components are heterogeneous rubberlike materials both components of which are in the rubbery state. Such blends consist usually of either a matrix and a discrete phase or two interpenetrating continuous phases (interpenetrating networks). At homogeneous deformations of such blends, the contribution of either component to the thermomechanical behaviour of the material is determined by the content of the component and the individual characteristics of its chains. 

Continuity can also be reached by polymerizing one of the components within the other. In such a case the blend is called an IPN, an interpenetrating network it is, in most cases formed by a thermoset in a thermoplastic polymer. An example is a compound built-up from 50% of a thermoplast (polycarbonate or polysulphone), and 50% of a cross-linked polymer on the basis of dicyanate bisphenol-A. The skeleton... 

Blends of BNIs and BMIswith Linear Polymers Semi-interpenetrated Network Concept... 

Jordhamo GM, MansonJA, Sperling LH (1986) Phase continuity and inversion in polymer blends and simultaneous interpenetrating networks. Poly Eng Sci 26 517... 

Short-Circuit Current. Key parameters for efficient charge collection by plastic solar cells are the hole and electron mobilities of the interpenetrating networks and the lifetime of the carriers within this network. While the lifetime of the carriers in the bulk heterojunction blends has already been discussed as a peculiarity of the interpenetrating network, the mobility of the individual components is a true material parameter. The interplay between network quality and mobility and their impact on the short-circuit current will be discussed by means of a simple model in this section. 

---