Blends and IPNs

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)... 

Miscible blends of poly(vinyl methyl ether) and polystyrene exhibit phase separation at temperatures above 100 C as a result of a lower critical solution temperature and have a well defined phase diagram ( ). This system has become a model blend for studying thermodynamics of mixing, and phase separation kinetics and resultant morphologies obtained by nucleation and growth and spinodal decomposition mechanisms. As a result of its accessible lower critical solution temperature, the PVME/PS system was selected to examine the effects of phase separation and morphology on the damping behavior of the blends and IPNs. 

Differential Scanning Calorimetry. Thermal analysis of PVME/PS blends and IPNs by DSC indicates only one glass transition temperature, which is located between the homopolymer T s. The position of Tg is dependent upon composition although it does not follow the prediction of the Fox equation (21), Table II. The breadth of the transition also increases significantly with increased PS content for the blends and IPNs. The broad transition might result from either the clustering of like mers near... 

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. 

While no crosslinker is mentioned in the patent, poly (ethyl acrylate) usually gels. That it was readily soluble suggests a low molecular weight. These early patents set the stage for today s latex blends and IPNs. 

Thiol-X Chemistries in Polymer and Materials Science 7 Natural Rubber Materials Volume 1 Blends and IPNs 8 Natural Rubber Materials Volume 2 Composites and Nanocomposites 9 Conjugated Polymers A Practical Guide to Synthesis 10 Polymeric Materials with Antimicrobial Activity From Synthesis to Applications... 

She has pnbhshed more than 45 papers in intematiorral and national refereed journals, more than 60 publications in conference proceedings, and more than 20 invited lectures for international conferences. She has been one of the editors of Malaysian Journal of Chemistry, Berita IKM- Chemistry in Malaysia, and books pnbhshed by Royal Society of Chemistry entitled Natural Rubber Materials, Volume 1 Blends and IPNs and Volume 2 Composites and Nanocomposites. She peer-reviews a few international journals on polymer science. Her research interest is devoted to modified natural rabber-based thermoplastic elastomers, biodegradable polyester/polyether blends, and solid polymer electrolytes... 

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. 

This book focuses on the recent trends in micro- and nanostructured polymer systems, particularly natural polymers, biopolymers, biomaterials, and their composites, blends, and IPNs. This valuable volume covers the occurrence, synthesis, isolation, production, properties and applications, modification, as well as the relevant analysis techniques to reveal the structures and properties of polymer systems. 

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.

Thiol-X Chemistries in Polymer and Materials Science 7 Natural Rubber Materials Volume 1 Blends and IPNs... 

Volume 1 of this book is comprised of 25 chapters, and discusses the different types of natural rubber based blends and IPNs. The first seven chapters discuss the general aspects of natural rubber blends like their miscibility, manufacturing methods, production and morphology development. The next ten chapters describe exclusively the properties of natural rubber blends with different polymers like thermoplastic, acrylic plastic, block or graft copolymers, etc. Chapter 18 deals entirely with clay reinforcement in natural rubber blends. Chapters 19 to 23 explain the major techniques used for characterizing various natural rubber based blends. The final two chapters give a brief explanation of life cycle analysis and the application of natural rubber based blends and IPNs. 

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